Quantum

Search for new state of matter expanded

Mon, 06 Apr 2020 23:04:38 +0000

Scientists have been striving to establish the existence of quantum spin liquids, a new state of matter, since the 1970s. A recent discovery physicists could help researchers solve the mystery and result in the next generation of computing.

Quantum computing meets particle physics for LHC data analysis

leah — Mon, 06 Apr 2020 16:40:16 +0000

From Physics World, April 3, 2020: A collaboration that includes Fermilab scientists is exploring how quantum computing could be used to analyze the vast amount of data produced by experiments on the Large Hadron Collider at CERN. The researchers have shown that a “quantum support vector machine” can help physicists make sense out of the huge amounts of information generated at CERN.

If I used Twitter…

Scott — Sat, 04 Apr 2020 23:34:39 +0000

I’m thinking of writing a novel where human civilization is threatened by a global pandemic, and is then almost singlehandedly rescued by one man … a man who reigned for decades as the world’s prototypical ruthless and arrogant tech billionaire, but who was then transformed by the love of his wife. That is, if the billionaire can make it past government regulators as evil as they are stupid. I need some advice: how can I make my storyline a bit subtler, so critics don’t laugh it off as some immature nerd fantasy?

European Commission Providing 3 Million Euro Grant for a New European Quantum Annealer Project

dougfinke1 — Fri, 03 Apr 2020 00:12:57 +0000

The AVaQus project will be coordinated by the newly created Quantum Computing Technologies group at the High Energy Physics Institute (IFAE) and is the first European-funded large-scale project on quantum annealing. The total amount of funding is 3 million Euros (about $3.25M USD) over a 3 year period. There are eight partners in this project including five research centers and three startups including:

Institut de Física d’Altes Energies (IFAE), Barcelona (Spain), acting as the coordinator of AVaQus
Karlrsruher Institut für Technologie (KIT), Karlsruhe (Germany)
Centre National de la Recherche Scientifique (CNRS), Grenoble (France)
University of Glasgow (UG), Glasgow (UK)
Consejo Superior de Investigaciones Científicas (CSIC), Madrid (Spain)
Delft Circuits (DELFT), Delft (The Netherlands)
Qilimanjaro Quantum Tech, S.L. (QILI), Barcelona (Spain)
HQS Quantum Simulations (HQS), Karlsruhe (Germany)

The key focus of this project will be to develop quantum annealing technology that has substantially better coherence times and qubit-qubit connectivity than current quantum annealers. The participants in this project believe that their quantum annealing technology may become a promising alternative to gate-based NISQ quantum computers for achieving useful applications in the short-to-medium term. The initial goal will be to demonstrate this with a five qubit prototype, but we expect the technology will be developed so it can be rapidly scaled to higher qubit counts afterwards. For additional information, you can view the news release announcing the project here and you can also visit the AVaQus web site here.

April 2, 2020

To tune up your quantum computer, better call an AI mechanic

Tue, 31 Mar 2020 20:22:41 +0000

A new article outlines a way to teach an AI to make an interconnected set of adjustments to the quantum dots that could form the qubits in a quantum computer's processor. Precisely tweaking the dots is crucial for transforming them into properly functioning qubits, and until now the job had to be done painstakingly by human operators, requiring hours of work to create even a small handful of qubits for a single calculation.

Quantum-entangled light from a vibrating membrane

Tue, 31 Mar 2020 17:00:19 +0000

Researchers recently entangled two laser beams through bouncing them off the same mechanical resonator, a tensioned membrane. This provides a novel way of entangling disparate electromagnetic fields, from microwave radiation to optical beams. Creating entanglement between optical and microwave fields would be a key step towards solving the challenge of sharing entanglement between two distant quantum computers operating in the microwave regime.

On “armchair epidemiology”

Scott — Tue, 31 Mar 2020 00:05:43 +0000

On Feb. 4, a friend sent me an email that read, in part:

Dr. A,
What do you make of this coronavirus risk? … I don’t know what level of precaution is necessary! Please share your view.

This was the first time that I’d been prompted to give this subject any thought whatsoever. I sent a quick reply two minutes later:

For now, I think the risk from the ordinary flu is much much greater! But worth watching to see if it becomes a real pandemic.

Strictly speaking, this reply was “correct”—even “reasonable” and “balanced,” admitting the possibility of changing circumstances. Yet if I could go back in time, I’d probably send a slightly different message—one that would fare better in the judgment of posterity. Something like this, maybe:

HOLY SHIT!!!!!—GET YOUR PARENTS SOMEWHERE SAFE—CANCEL ALL TRAVEL PLANS—STOCK UP ON FOOD AND MASKS AND HAND SANITIZERS. SELL ALL STOCK YOU OWN!!! SHORT THE MARKET IF YOU KNOW HOW, OTHERWISE GET CASH AND BONDS. HAVE AN ISOLATED PLACE TO ESCAPE TO. IF YOU’RE FEELING ALTRUISTIC, JOIN GROUPS MAKING THEIR OWN MASKS AND VENTILATORS.
DO NOT RELY ON OFFICIAL PRONOUNCEMENTS, OR REASSURING ARTICLES FROM MAINSTREAM SOURCES LIKE VOX OR THE WASHINGTON POST. THE CDC AND OTHER FEDERAL AGENCIES ARE ASLEEP AT THE WHEEL, HOLLOWED-OUT SHELLS OF WHAT YOU IMAGINE THEM TO BE. FOR ALL IT WILL DO IN ITS MOMENT OF ULTIMATE NEED, IT WOULD BE BETTER IF THE CDC NEVER EXISTED.
WHO THEN SHOULD YOU LISTEN TO? CONTRARIAN, RATIONALIST NERDS AND TECH TYCOONS ON SOCIAL MEDIA. BILL GATES, BALAJI SRINIVASAN, PAUL GRAHAM, GREG COCHRAN, ROBIN HANSON, SARAH CONSTANTIN, ELIEZER YUDKOWSKY, NICHOLAS CHRISTAKIS, ERIC WEINSTEIN. NO, NOT ALL SUCH PEOPLE—NOT ELON MUSK, FOR EXAMPLE—BUT YOU’LL DO RIDICULOUSLY BETTER THAN AVERAGE THIS WAY.
BASICALLY, THE MORE SNEERCLUB WOULD SNEER AT A GIVEN PERSON, THE MORE THEY’D CALL THEM AN AUTODIDACT STEMLORD DUNNING-KRUGER ASSHOLE WHO’S THE EMBODIMENT OF EVERYTHING WRONG WITH NEOLIBERAL CAPITALISM, THE MORE YOU SHOULD LISTEN TO THAT PERSON RIGHT NOW FOR THE SAKE OF YOUR AND YOUR LOVED ONES’ FUCKING LIVES.
DON’T WORRY: WITHIN 6-8 WEEKS, WHAT THE CONTRARIANS ARE SAYING TODAY WILL BE CONVENTIONAL WISDOM. THE PUBLICATIONS THAT NOW SNEER AT PANDEMIC PREPPERS WILL TURN AROUND AND SNEER AT THE IRRESPONSIBLE NON-PREPPERS, WITHOUT EVER ADMITTING ERROR. WE’LL ALWAYS HAVE BEEN AT WAR WITH OCEANIA—OR RATHER CORONIA. TRUTH, OFFICIAL RECOMMENDATIONS, AND PROGRESSIVE POLITICS WILL GET BACK INTO ALIGNMENT JUST LIKE THEY NORMALLY ARE, AND WE’LL ALL BE SHARING MEMES JUSTLY DENOUNCING TRUMP AND THE CRAVEN REPUBLICAN SENATORS AND EVANGELICAL PASTORS AND NUTTY CONSPIRACY THEORISTS WHO DON’T CARE HOW MANY LIVES THEY SACRIFICE WITH THEIR DENIALS.
BUT EVEN THOUGH THE ENLIGHTENED MAINSTREAM WILL FIGURE OUT THE TRUTH IN A MONTH OR SO—AND EVEN THOUGH THAT’S FAR BETTER THAN OUR IDIOT PRESIDENT AND MILLIONS OF HIS FOLLOWERS, WHO WILL UNDERSTAND ONLY AFTER THE TRENCHES OVERFLOW WITH BODIES, IF THEN—EVEN SO, WE DON’T HAVE A MONTH. IF YOU WANT TO BE AHEAD OF THE SENSIBLE MAINSTREAM, THEN ALMOST BY DEFINITION, THAT MEANS YOU NEED TO LISTEN TO THE POLITICALLY INCORRECT, CRAZY-SOUNDING ICONOCLASTS: TO THOSE WHO, UNLIKE YOU AND ALSO UNLIKE ME, HAVE DEMONSTRATED THAT THEY DON’T CARE IF PEOPLE SNEER AT THEM.

Of course, I would never have sent such an email, and not only because of the bold and all-caps. My whole personality stands against every sentence. I’ve always taken my cues from “mainstream, reasonable, balanced” authorities, in any subject where I’m not personally expert. That heuristic has generally been an excellent way to maximize expected rightness. But when it fails … holy crap!

Now, and for the rest of my life, I’ll face the question: what was wrong with me, such that I would never have sent a “nutty” email like the one above? Can I fix it?

More specifically, was my problem intellectual or emotional? I lean toward the by mid-to-late February, as more and more of my smartest friends started panicking and told me why I should too, I was intellectually on board with the idea that millions of people might die as the new virus spread around the world, and I affirmed as much on Facebook and elsewhere. And yet it still took me a few more weeks to get from “millions could die” to “HOLY SHIT MILLIONS COULD DIE—PANIC—DROP EVERYTHING ELSE—BUILD MORE VENTILATORS!!!!“

A viral article implores us to “flatten the curve of armchair epidemiology”—that is, to listen only to authoritive sources like the CDC, not random people spouting on social media. This was notable to me for being the diametric opposite of the actual lesson of the past two months. It would be like taking the lesson from the 2008 financial crisis that from now on, you would only trust serious rating agencies, like Moody’s or Standard & Poor.

Oh, but I forgot to tell you the punchline. A couple days ago, the same friend who emailed me on February 4, emailed again to tell me that both of her parents (who live outside the US) now have covid-19. Her father had to go to the emergency room and tested positive. Her mother stayed home with somewhat milder symptoms. Given the overloaded medical system in their country, neither can expect a high standard of care. My friend has spent the past few days desperately trying to get anyone from the hospital on the phone.

This post represents my apology to her. Like, it’s one thing to be so afraid of the jeers of the enlightened that you feign asexuality and live as an ascetic for a decade. It’s worse to be so afraid that you fail adequately to warn your friends when you see an exponential function coming to kill their loved ones.

Tiny optical cavity could make quantum networks possible

Mon, 30 Mar 2020 19:22:22 +0000

Engineers have shown that atoms in optical cavities could be foundational to the creation of a quantum internet.

Paycheck Protection Program May Be of Help to U.S. Based Quantum Startup Companies

dougfinke1 — Sun, 29 Mar 2020 22:00:49 +0000

The U.S. Small Business Administration (SBA) is offering a new program that may be of interest to small quantum companies that are under economic pressure due to the coronavirus situation. The Coronavirus Aid, Relief, and Economic Security (CARES) Act has allocated $350 billion to help small businesses keep workers employed amid the pandemic and economic downturn. Known as the Paycheck Protection Program, the initiative provides 100% federally guaranteed loans to small businesses. Companies will not be required to provide a personal guarantee or collateral in order to receive the loan. Perhaps of most interest, these loans may be forgiven for those companies that maintain their payrolls during the crisis or restore them afterwards. The loan is available to companies with 500 employees or less and can cover employee payroll costs, mortgages, rent, and utilities. The loan amount is 2.5 times the average total monthly payroll costs incurred by a company during the year prior to the loan date up to a maximum of $10 million. The SBA will be issuing additional guidance and information about eligible lenders very soon, but in the meantime you can read a summary from the U.S. Chamber of Commerce here and an FAQ about the program here.

March 29, 2020

DARPA Provides $8.6M Award to Team of Rigetti, NASA-Quail, and USRA for Research in Quantum Optimization

dougfinke1 — Fri, 27 Mar 2020 23:37:05 +0000

The U.S. Defense Advanced Projects Research Agency (DARPA) has provided an $8.6 million award over four years to a team including the Universities Space Research Assocation (USRA), Rigetti Computing, and NASA’s Quantum Artificial Intelligence Laboratory (QuAIL). The research will focus on advancing quantum hardware/software to help solve optimization problems such as scheduling and asset allocation. The grant is a part of the DARPA’s Optimization with Noisy Intermediate-Scale Quantum program (ONISQ) program which has a goal of establishing that quantum information processing using NISQ devices has a quantitative advantage for solving real-world-combinatorial optimization problems. These types of problems have a lot of applications within the U.S. military.

A key element of this research will be to leverage the Quantum Approximate Optimization Algorithm (QAOA) which uses a hybrid classical-quantum approach for solving these types of optimization problems. The Rigetti hardware has certain features, such as the colocation of the classical and the quantum computers, which provides performance advantages for these types of algorithms. Rigetti is also developing multi-core versions of their quantum computer which will exceed 100 qubits and we expect those machines to be used eventually in this program.

In general, the Rigetti team will be supplying the hardware while the NASA/USRA team will be concentrating on the algorithms. The NASA/USRA team will also work on benchmarking the algorithms against the high performance classical solutions so they can determine when a quantum advantage is achieved. There will also be certain areas where the teams will jointly study hardware/software tradeoffs to improve overall performance of the algorithms.

We asked the people at Rigetti if the team working on this program would be eligible for the $1 Million Quantum Advantage prize announced in September 2018 if it is successful. Apparently, the Rigetti employees and partners are excluded from winning the prize so it would still be available to other end users.

For more information, you can views Rigetti’s news release about the award here, USRA’s news release here, and a description of the ONISQ program on the DARPA web site here.

March 27, 2020

Physicist develops new photon source for tap-proof communication

Fri, 27 Mar 2020 20:17:24 +0000

An international team has developed a new method for generating quantum-entangled photons in a spectral range of light that was previously inaccessible. The discovery can make the encryption of satellite-based communications much more secure in the future.

Quantum phenomenon governs organic solar cells

Thu, 26 Mar 2020 16:41:33 +0000

Researchers have discovered a quantum phenomenon that influences the formation of free charges in organic solar cells.

A key development in the drive for energy-efficient electronics

Mon, 23 Mar 2020 16:55:49 +0000

Scientists have made a breakthrough in the development of a new generation of electronics that will require less power and generate less heat. It involves exploiting the complex quantum properties of electrons -- in this case, the spin state of electrons.

Researchers observe ultrafast processes of single molecules for the first time

Mon, 23 Mar 2020 14:48:03 +0000

Researchers describe how a molecule moves in the protective environment of a quantum fluid.

Chip-based device opens new doors for augmented reality and quantum computing

Thu, 19 Mar 2020 23:41:39 +0000

Researchers have designed a new chip-based device that can shape and steer blue light with no moving parts. The device could greatly reduce the size of light projection components used for augmented reality and a variety of other applications.

Scientists create quantum sensor that covers entire radio frequency spectrum

Thu, 19 Mar 2020 20:15:29 +0000

A quantum sensor could give Soldiers a way to detect communication signals over the entire radio frequency spectrum, from 0 to 100 GHz, said researchers.

Chip-based devices improve practicality of quantum-secured communication

Thu, 19 Mar 2020 18:10:30 +0000

Researchers have demonstrated new chip-based devices that contain all the optical components necessary for quantum key distribution while increasing real-world security. The fast and cost-effective platform is poised to facilitate implementation of extremely secure data communication that can be used to protect everything from emails to online banking information.

Ask Me Anything: Apocalypse Edition

Scott — Wed, 18 Mar 2020 21:02:37 +0000

So far, I confess, this pandemic is not shaping up for me like for Isaac Newton. It’s not just that I haven’t invented calculus or mechanics: I feel little motivation to think about research at all. Or to catch up on classic literature or films … or even to shower, shave, or brush my teeth. I’m quarantined in the house with my wife, our two kids, and my parents, so certainly there’s been plenty of family time, although my 7-year-daughter would inexplicably rather play fashion games on her iPad than get personalized math lessons from the author of Quantum Computing Since Democritus.

Mostly, it seems, I’ve been spending the time sleeping. Or curled up in bed, phone to face, transfixed by the disaster movie that’s the world’s new reality. Have you ever had one of those nightmares where you know the catastrophe is approaching—whether that means a missed flight, a botched presentation at old former high school, or (perhaps) more people dying than in any event since WWII—but you don’t know exactly when, and you can do nothing to avert it? Yeah, that feeling is what I now close my eyes to escape. And then I wake up, and I’m back in bizarro-nightmare-land, where the United States is in no rush whatsoever to test people or to build ventilators or hospitals to cope with the coming deluge, and where ideas that could save millions have no chance against the rot in our institutions.

If nothing else, I guess we now have a decisive answer to the question of why humanity can’t get its act together on climate change. Namely, if we can’t wrap our heads around a catastrophe that explodes exponentially over a few weeks—if those who denied or minimized it face no consequences even when they’re dramatically refuted before everyone’s eyes—then what chance could we possibly have against a catastrophe that takes a century? (Note that I reject the view that the virus was sent by some guardian angel as the only possible solution to climate change, one crisis cancelling another one. For one thing, I expect emissions to roar back as soon as this new Black Death is over; for another, the virus punishes public transportation but not cars.)

Anyway, I realized I needed something, not necessarily to take my mind off the crisis, but to break me out of an unproductive spiral. Also, what better time than the present for things that I wouldn’t normally have time for? So, continuing a tradition from 2008, 2009, 2011, 2013, 2015, and 2018, we’re going to do an Ask Me Anything session. Questions directly or tangentially related to the crisis (continuing the discussion from the previous thread) are okay, questions totally unrelated to the crisis are even okayer, goofball questions are great, and questions that I can involve my two kids in answering are greatest of all. Here are this year’s ground rules:

24 hours or until I get bored
One question per person total
Absolutely no multi-part questions
Self-contained questions only—nothing that requires me to read a paper, watch a video, etc.
Scan the previous AMAs to see if your question is already there
Any sufficiently patronizing, hostile, or annoying questions might be left in the moderation queue, 100% at my discretion

So ask away! And always look on the bright side of life.

Coronavirus and Quantum Computing

dougfinke1 — Tue, 17 Mar 2020 19:23:34 +0000

As someone who made it through the downturns of the DotCom Bubble and 9/11 Events of 2000-2001 as well as the Financial Crisis of 2008, we are confident that the quantum industry will bounce back stronger than ever once the coronavirus crisis passes over; similar to what occurred previously. However, we do expect that today’s situation with the coronavirus will have a definite short term impact on the quantum computing market. The lockdowns, social distancing and other measures will last several months and will also trigger a global recession that will last several more months after the virus itself is under control. It probably will be tough going for the next year for many quantum companies. The key during this time is to position your company so that when the virus is contained and the recession is over, your company will be in the best position to come roaring out of the gate and flourish. Companies that achieved this after the 2000-2001 downturn include Amazon, EBay, and Priceline. After the 2008 Financial Crisis, companies such as NetFlix, Groupon and Airbnb did well too.

So here are our thoughts on selected topics of what to expect and how to manage through this based upon our previous experience:

Hardware Progress Will Slow in 2020, but Software Progress Will Not
In a previous article, we had forecasted that quantum computing qubit counts would achieve a Moore’s Law like doubling every 1-2 years. By that measure we had expected to see in 2020 gate level machines with qubit counts in the 100-200 range. Although many quantum researchers will be able to work from home (see below), it is much more difficult for hardware engineers to be as productive while doing so. There could be supply chain disruptions if some of their components vendors reduce production or even divert resources to build more components for critical medical related markets. Although there may still be some announcements of higher performing machines towards the end of this year, it is probable that these would occur several months later than originally planned.

Software development will be a completely different story. Since access to quantum computers is already cloud based, it matters little where the job is submitted from. Software programmers are quite adept at using all the online tools available for software development and team coordination so we expect that most of their work will stay on schedule.

New Business Development in the Enterprise Market Will Get a Lot Harder In the Near Term
In times of uncertainty, corporate managers are much less eager to take risks or start up new efforts. In addition, with so many people working at home decision-making will be slower than normal even for those projects that eventually get approved. For those of you who were projecting you would get a bunch of new customers in 2020, you will likely be disappointed.

Raising More Venture Capital Will Also Be a Big Challenge in the Near Term
We had previously heard even before the coronavirus that some quantum startups were having difficulty closing new funding rounds. Many potential investors were concerned about the long lead-times to get a return on their investment, a possible quantum winter, too many startups, and other things. Due to all the uncertainties, venture investors will now have another reason to delay fundings due to the overall economic situation.

Government Funding
There is one big difference between the current situation and the DotCom Bubble and Financial Crises before. Governments did not have in place large funding programs for DotCom companies in 2000 nor were they providing any grants to the large financial companies prior to 2007. Even after the DotCom bubble burst in 2001, the government still did not provide bailout funds to the DotCom companies. Once the Financial Crisis hit, the situation was different and the government did provide large bailout loans because they deemed some of these firms as “too big to fail”.

Today, there are already several large (> $1 billion) government programs that were previously established to support quantum computing. These include the United States National Quantum Initiative Act, the European Union’s Quantum Flagship, the Chinese national laboratories, India’s National Mission on Quantum Technologies and Applications, and several others. These programs will certainly not be decreased during a recession and could possibly be increased as part of a stimulus efforts. Many governments view having a strong quantum computing capability as a key national security issue.

Companies that haven’t pursued in the past getting government funding grants as aggressively as they might have should take another look at these programs and see if they can win some to offset any business that might be lost in the commercial sector. As this article is being written we are hearing of additional economic stimulus packages being proposed by government including low-cost loans and other measures. Although we are not certain if any of these will be applicable to a quantum computing company, it will still be worth examining them once the programs are finalized.

Watch Your Expenses
The venture capital firm, Sequoia Capital, recently put out a memo to all their portfolio companies that conveys this message better than we ever could. We recommend you read the letter here.

Work at Home Will Become Both a Temporary as Well as a Permanent Thing for Some People
Due to the virus, a large majority of companies are encouraging their employees to work at home. We expect that this change will have a lot of ramifications that go beyond the near term. For one, we expect that some workers as well as their employers will discover that working at home will actually increase productivity. There may be less distractions (depending upon your home situation) and fewer time-wasting meetings. In addition, we think that many of these new at-home workers will be forced to learn new skills, such as use of the Zoom or Webex video conferencing programs or the Slack messaging platform, that make them more productive. Workers who don’t have to commute to an employer’s facility won’t have to deal with traffic and may save a significant amount of time each work day. Once the lockdowns due to the virus are over, we expect that there will be a much larger permanent work-at-home workforce than we had previously. And employers that were reluctant to allow this in the past, will be a lot more willing to do so once they see that this arrangement does not impair and may even improve productivity.

This will have some interesting aspects for quantum computing. With an extra hour or two in their day because they are no longer commuting, some employees may have time available to receive increased training on things like programming quantum computers. Quantum companies may want to take advantage of this to improve the quality of their documents or create training videos that demonstrate their products and how they can be used for different applications. Although the quantum companies may not get immediately purchase orders from the corporate managers, they will gain mindshare with the employees who work for them and this will turn into new business once the economic conditions get better.

Laid Off Employees Will be Seeking to Develop New Skills
Unfortunately, as the economy moves to a recession some companies will have problems and will need to lay off good employees. Like the at-home workers mentioned above, these people will also have time available and may be interested in studying quantum computing. You can use the same collateral material mentioned above to help these folks get training too. And when the economy improves, they will be able to find employment at another company and recommend use of your product. Or perhaps, you can hire these folks for yourself, once you are ready to resume hiring.

Will Quantum Computing Be Able to Contribute in Solving the Current Coronavirus Problems?
Unfortunately, we do not think so. We do believe that solutions including vaccines and treatment protocols will be developed using classical means within the next 12-18 months and the current state of quantum computing is just not far advanced enough to make a meaningful contribution in that time frame. However, in a few years from now when quantum computers are much more powerful, coronavirus will be studied to help understand where quantum computers could be used for any future similar situation. So although quantum computing won’t be able to help by simulating the virus or discovering a drug this time around, it is likely that when another pandemic comes up they will make a difference. People say that these pandemics are a once every 100 years phenomena. So if we do see some new pandemic in the year 2120, you can be certain that your great-grandchildren will be able to leverage quantum computing and create a quick solution to fight it!

Conclusion
So although things will be tough in the near term, we still expect a very bright future for quantum computing this decade. Recessions have a way of winnowing out the weaker companies but the companies that make it through will be stronger and posed for success. Think about how you can make your company be one of these. Look for those areas where you can create a differential advantage and provide a unique service or capability or approach that the others don’t have. Think about the issues your future customers may face and see what you can start developing now to solve those problems. If you do have the money available, there may be some good opportunities to pick up some great members for your team. We expect that workforce availability will be a continuing problem throughout the 2020’s and it may be easier to recruit good quantum folks now because once the economy picks up again, recruiting will likely get a lot tougher.

But most important, keep up the optimism and stay healthy. Good luck!

March 17, 2020

Devs, determinism and maybe-dead cats

leah — Mon, 16 Mar 2020 15:00:03 +0000

From Northern Public Radio's The STEM Read Podcast, March 13, 2020: Then Gillian King-Cargile interviews Fermilab Education and Public Outreach Head Rebecca Thompson to unpack the topics of quantum mechanics, determinism and quantum computing. Thompson is the creator of the Spectra comic book series and author of "Fire, Ice, and Physics: The Science of Game of Thrones."

Google Releases TensorFlow Quantum for Machine Learning and qsim/qsimh High Performance Simulators

dougfinke1 — Fri, 13 Mar 2020 05:34:47 +0000

TensorFlow was originally released by Google in 2015 as a machine learning system that runs on classical computers including CPUs, GPUs, and TPUs. The classical version is still in wide use today both inside and external to Google for a number of applications. Google announcement unveils a new version called TensorFlow Quantum that is open sourced and integrates with their Cirq quantum computer programming language. It it is used in a hybrid quantum-classical configuration to allow the rapid prototyping of quantum machine learning models.

Example of a Hybrid Quantum-Classical Neural Network using TensorFlow Quantum. Source: Google

With the classical and the quantum computers working together, the steps to run a quantum machine learning model as as follows:

Prepare a quantum dataset
Evaluate a quantum neural network model
Measure the resultant quantum states as either a sample or an average over several runs
Evaluate a classical neural networks model
Evaluate a cost function
Update the gradients and parameters in a direction expected to decrease the cost. Then, go to step 2 and repeat until the cost function can no longer be decreased.

Steps number 2 and 3 can be run on either a quantum processor, such as their Sycamore chip, or on a quantum simulator. In conjunction with this announcement, Google also released open sourced versions of the high performance qsim and qsimh simulators. These simulators were used for cross entropy benchmarking in Google’s Quantum Supremacy Experiment. qsim is a Schrödinger full state-vector simulator. It computes all the 2ⁿ amplitudes of the state vector, where n is the number of qubits. qsim is significantly faster than the native simulator built in to Cirq. In Google’s arXiv paper they showed a 7 times improvement for a 20 qubit random circuit with a depth of 20 and a 100 times improvement for structured circuit of the same size. qsimh is a hybrid Schrödinger-Feynman simulator that uses a technique of splitting the lattice into two parts.

Google has released a lot of information related to these products. Here are links to the documentation and the software.

March 12, 2019

Perturbation-free studies of single molecules

Thu, 12 Mar 2020 18:23:05 +0000

Researchers of the University of Basel have developed a new method with which individual isolated molecules can be studied precisely -- without destroying the molecule or even influencing its quantum state. This highly sensitive technique for probing molecules is widely applicable and paves the way for a range of new applications in the fields of quantum science, spectroscopy and chemistry.

First it came for Wuhan

Scott — Thu, 12 Mar 2020 13:16:15 +0000

Scott’s foreword: This week Steve Ebin, a longtime Shtetl-Optimized reader (and occasional commenter) from the San Francisco tech world, sent me the essay below. Steve’s essay fit too well with my own recent thoughts, and indeed with this blog’s title, for me not to offer to share it here—and to my surprise and gratitude, Steve agreed.

I guess there are only two things I’d add to what Steve wrote. First, some commenters took me to task for a misplaced emphasis in my last coronavirus post, and on further reflection, I now concede that they were right. When a preventable catastrophe strikes the world, what’s always terrified me most are not the ranting lunatics and conspiracy theorists, even if some of those lunatics actually managed to attain the height of power, from where they played a central role in the catastrophe. No, what’s terrified me more are the blank-faced bureaucrats who’ve signed the paperwork that amounted to death warrants. Like, for example, the state regulators who ordered the Seattle infectious disease expert to stop, after she’d had enough of the government’s failure to allow corona tests, took it upon herself to start testing anyway, and found lots of positive results. Notably, only some countries have empowered lunatics, but the blank-faced bureaucrats rule everywhere unless something stronger overrides them.

Second, I’ll forever ask myself what went wrong with me, that it took me until metaphorical 1939 to acknowledge the scale of an unfolding catastrophe (on more than a purely intellectual level)—even while others were trying to tell me way back in metaphorical 1933. Even so, better metaphorical 1939 than metaphorical 1946.

Without further ado, Steve’s essay:

The most expensive meal I ever ate was in San Francisco at a restaurant called Eight Tables. As the name implies, the restaurant has only eight tables. The meal cost $1,000 and featured 12 courses, prepared by award-winning chefs.

The most expensive meal a person ever ate was in late 2019, in China, and consisted of under-cooked bat meat. It cost trillions of dollars. The person who ate it, possibly a peasant, changed the course of the 21st century. The bat he ate contained a virus, and the virus threatened to spread from this man to the rest of humanity.

I’m making up some details, of course. Maybe the man wasn’t a peasant. Or he could have been a woman. Or the bat could have been a pangolin. Or maybe, through a lucky accident (the guy was a loner perhaps), it could have not spread. That could have happened, but it didn’t. Or maybe sometimes that does happen and we don’t know it. These are just accidents of history.

I’m writing this on March 9, 2020. The good news is that the virus, in its current form, doesn’t kill children. I am so thankful for that. The bad news is that the virus does kill adults. The virus is like a grim reaper, culling the sick, the debilitated, and the elderly from the population. It attacks the pulmonary system. I heard a 25-year-old survivor describing how he became unable to control his breathing and could not fall asleep or he would die. Even for healthy young people, the prognosis is often poor.

There were Jews in Europe in the 1930s who sat around tables with the elders of their families and villages and debated whether to leave for America, or Palestine, or South America. Most of them, including my grandmother’s family, didn’t leave, and were largely exterminated. The virus of the time was Nazism, and it too attacked the pulmonary systems of the old and the debilitated, in that case with poisonous gasses.

When you grow up as I did, you are taught to have a paranoia in the back of your mind that there is a major disaster about to happen. That a holocaust, or something of that magnitude, might occur in your lifetime. And so you are never complacent. For your whole life, you’re looking and waiting for a history changing event. You try to ensure that you are willing to follow your thoughts to their logical conclusion and take the necessary actions as a result, unlike many of the Jews of 1930s Europe, who refused to confront the obstacle in front of them until it was too late, and unlike many politicians and world leaders today, who are doing the same.

And the conclusion we must now confront is clear. We are watching a once-in-a-century event unfold. Coronavirus–its mutations, its spawn–will change the course of human history. It will overwhelm our defense system and may kill millions. It may continue to mutate and kill millions more. We will develop painful social measures to slow its spread. We will produce vaccines and better treatment protocols. Some of this will help, but none of this will work perfectly. What will happen to society as this unfolds?

My favorite biblical verse comes from Ecclesiastes: To everything there is a season, and a time to every purpose under the heaven. A time to be born, and a time to die. A time to plant and a time to pluck that which is planted. And so on.

The season has changed, and the seven years of famine have begun.

Novel error-correction scheme developed for quantum computers

Wed, 11 Mar 2020 16:33:13 +0000

Experimental quantum computers are plagued with errors. Researchers now offer a novel method to reduce errors in a scheme applicable across different types of quantum hardware.

Engineers crack 58-year-old puzzle on way to quantum breakthrough

Wed, 11 Mar 2020 16:18:22 +0000

A mishap during an experiment led quantum computing researchers to crack a mystery that had stood since 1961.

New error correction method provides key step toward quantum computing

Wed, 11 Mar 2020 15:20:01 +0000

A new project devised a novel approach for quantum error correction that could provide a key step toward practical quantum computers, sensors and distributed quantum information that would enable the military to potentially solve previously intractable problems or deploy sensors with higher magnetic and electric field sensitivities.

National disgrace

Scott — Tue, 10 Mar 2020 17:07:03 +0000

In this blog’s now 15-year-history, at Waterloo and then MIT and now UT Austin, I’ve tried to make it clear that I blog always as Scott, never as Dr. Aaronson of Such-and-Such Institution. (God knows I’ve written a few things that a prudent dean might prefer that I hadn’t—though if I couldn’t honestly say that, in what sense would I even enjoy “academic freedom”?) Today, though, for only about the second time, I’m also writing as a professor motivated by a duty of care toward his students.

A week ago, most of my grad students were in the Bay Area for a workshop; they then returned and spent a week hanging around the CS building like normal. Yesterday I learned that at least one of those students developed symptoms consistent with covid19. Of course, it’s much more likely to be a boring cold or flu—but still, in any sane regime, just to be certain, such a person would promptly get tested.

After quarantining himself, my student called the “24/7 covid19 hotline” listed in an email from the university’s president, but found no one answering the phone over the weekend. Yesterday he finally got through—only to be told, flatly, that he couldn’t be tested due to insufficient capacity. When I heard this, I asked my department chair and dean to look into the matter, and received confirmation that yeah, it sucks, but this is the situation.

If it’s true that, as I’ve read, the same story is currently playing itself out all over the country, then this presumably isn’t the fault of anyone in UT’s health service or the city of Austin. Rather, as they say in the movies, it goes all the way to the top, to the CDC director and ultimately the president—or rather, to the festering wound that now sits where the top used to be.

Speaking of movies, over the weekend Dana and I watched Contagion, as apparently many people are now doing. I confess that I’d missed it when it came out in 2011. I think it’s a cinematic masterpiece. It freely violates many of the rules of movie narrative: characters are neither done in by their own hubris, nor saved by their faith or by being A-list stars. But Contagion is also more than a glorified public service announcement about the importance of washing your hands. It wants to show you the reality of the human world of its characters, and also the reality of a virus, and how the two realities affect each other despite obeying utterly different logic. It will show a scene that’s important to the charaters for human reasons, and then it will show you the same scene again, except this time making you focus on whose hand touched which surface in which order.

But for all its excellence and now-obvious prescience, there are two respects in which Contagion failed to predict the reality of 2020. The first is just a lucky throw of the RNA dice: namely, that the real coronavirus is perhaps an order of magnitude less fatal than the movie virus, and for some unknown reason it spares children. But the second difference is terrifying. All the public health authorities in the movie are ultra-empowered and competent. They do badass things like injecting themselves with experimental vaccines. If they stumble, it’s only in deeply understandable ways that any of us might (e.g., warning their own loved ones to evacuate a city before warning the public).

In other words, when the scriptwriters, writing their disaster movie, tried to imagine the worst, they failed to imagine a US government that would essentially abandon the public, by

(1) botching a simple test that dozens of other countries performed without issue,
(2) preventing anyone else from performing their own tests, and then
(3) turning around and using the lack of positive test results to justify its own inaction.

They failed to imagine a CDC that might as well not exist for all it would do in its hour of need: one that didn’t even bother to update its website on weekends, and stopped publishing data once the data became too embarrassing. The scriptwriters did imagine a troll gleefully spreading lies about the virus online, endangering anyone who listened to him. They failed to imagine a universe where that troll was the president.

“I mean, don’t get me wrong,” they told me. “Trump is a racist con artist, a demagogue, the precise thing that Adams and Hamilton and Franklin tried to engineer our republic to avoid. Just, don’t get so depressed about it all the time! Moaning about how we’re trapped in a freakishly horrible branch of the wavefunction, blah blah. I mean look on the bright side! What an incredible run of luck we’ve had, that we elected a president with the mental horizons of a sadistic toddler, and yet in three years he hasn’t caused even one apocalypse. You’re alive and healthy, your loved ones are alive and healthy. It could be a lot worse!”

The above, I suspect, is a sentiment that will now forever date any writing containing it to January 2020 or earlier.

Particle accelerator technology could solve one of the most vexing problems in building quantum computers

leah — Mon, 09 Mar 2020 18:44:50 +0000

From HPC Wire, March 2, 2020: Fermilab scientists are collaborating with researchers at Argonne, where they'll run simulations on high-performance computers. Their work will help determine whether instruments called superconducting radio-frequency cavities, also used in particle accelerators, can solve one of the biggest problems facing the successful development of a quantum computer: the decoherence of qubits.

New software combines quantum and classical machine learning

12011 — Mon, 09 Mar 2020 00:00:00 +0000

Monday, March 9, 2020

Five University of Waterloo students have teamed up with Google to develop software to accelerate machine learning using quantum science.

The collaborative effort resulted in the creation of an open-source hybrid quantum-classical machine learning software platform, called TensorFlow Quantum.

Un nouveau logiciel combine les apprentissages automatiques classique et quantique

12011 — Mon, 09 Mar 2020 00:00:00 +0000

Monday, March 9, 2020

In English.

Cinq étudiants de l’Université de Waterloo ont fait équipe avec Google pour mettre au point un logiciel accélérant l’apprentissage automatique à l’aide de la physique quantique.

Coronavirus: the second-weirdest solution?

Scott — Fri, 06 Mar 2020 22:21:52 +0000

Many people have suggested coating handles, doorknobs and so forth with virus-killing copper tape. It’s a shame that this isn’t being tried on a wider scale. In the meantime, though, here’s a related but different idea that I had last night.

Imagine we could coat every doorknob, every light switch, every railing, every other surface that people might touch in public buildings, with some long-lasting disgusting, sticky, slimy substance. For a variety of reasons, one probably wouldn’t use actual excrement, although it wouldn’t hurt if the substance looked like that. Or it could be a sickly neon green or red, to make it impossible to conceal when you’d gotten the substance on your hands.

What would be the result? Of course, people would avoid touching these surfaces. If they had to, they’d do so with a napkin or glove whenever possible. If they had to touch them bare-handedly, they’d rush to wash their hands with soap as soon as possible afterwards. Certainly they wouldn’t touch their faces before having washed their hands.

In short, they’d show exactly the behaviors that experts agree are among the most helpful, if our goal is to slow the spread of the coronavirus. In effect, we’d be plugging an unfortunate gap in our evolutionary programming—namely, that the surfaces where viruses can thrive aren’t intuitively disgusting to us, as (say) vomit or putrid meat are—by making those surfaces disgusting, as they ought to be in the middle of a pandemic.

Note that, even if it somehow turns out to be infeasible to coat all the touchable surfaces in public buildings with disgusting goo, you might still derive great personal benefit from imagining them so covered. If you manage to pull that off, it will yield just the right heuristic for when and how often you should now be washing your hands (and avoiding touching your face), without no need for additional conscious reflection.

Mostly, having the above thoughts made me grateful for my friend Robin Hanson. For as long Robin is around, tweeting and blogging from his unique corner of mindspace, no one will ever be able to say that my ideas for how to control the coronavirus were the world’s weirdest or most politically tone-deaf.

A filter for cleaner qubits

Fri, 06 Mar 2020 17:26:04 +0000

Researchers show theoretically how coupling an additional filter qubit to the control line of a quantum computer can greatly increase the lifetime of the information stored in it. This work can help make quantum computers more robust and accurate.

Novel method for easier scaling of quantum devices

Rob Matheson | MIT News Office — Fri, 06 Mar 2020 04:59:59 +0000

In an advance that may help researchers scale up quantum devices, an MIT team has developed a method to “recruit” neighboring quantum bits made of nanoscale defects in diamond, so that instead of causing disruptions they help carry out quantum operations.

Quantum devices perform operations using quantum bits, called “qubits,” that can represent the two states corresponding to classic binary bits — a 0 or 1 — or a “quantum superposition” of both states simultaneously. The unique superposition state can enable quantum computers to solve problems that are practically impossible for classical computers, potentially spurring breakthroughs in biosensing, neuroimaging, machine learning, and other applications.

One promising qubit candidate is a defect in diamond, called a nitrogen-vacancy (NV) center, which holds electrons that can be manipulated by light and microwaves. In response, the defect emits photons that can carry quantum information. Because of their solid-state environments, however, NV centers are always surrounded by many other unknown defects with different spin properties, called “spin defects.” When the measurable NV-center qubit interacts with those spin defects, the qubit loses its coherent quantum state — “decoheres”— and operations fall apart. Traditional solutions try to identify these disrupting defects to protect the qubit from them.

In a paper published Feb. 25 in Physical Letters Review, the researchers describe a method that uses an NV center to probe its environment and uncover the existence of several nearby spin defects. Then, the researchers can pinpoint the defects’ locations and control them to achieve a coherent quantum state — essentially leveraging them as additional qubits.

In experiments, the team generated and detected quantum coherence among three electronic spins — scaling up the size of the quantum system from a single qubit (the NV center) to three qubits (adding two nearby spin defects). The findings demonstrate a step forward in scaling up quantum devices using NV centers, the researchers say.

“You always have unknown spin defects in the environment that interact with an NV center. We say, ‘Let’s not ignore these spin defects, which [if left alone] could cause faster decoherence. Let’s learn about them, characterize their spins, learn to control them, and ‘recruit’ them to be part of the quantum system,’” says the lead co-author Won Kyu Calvin Sun, a graduate student in the Department of Nuclear Science and Engineering and a member of the Quantum Engineering group. “Then, instead of using a single NV center [or just] one qubit, we can then use two, three, or four qubits.”

Joining Sun on the paper are lead author Alexandre Cooper ’16 of Caltech; Jean-Christophe Jaskula, a research scientist in the MIT Research Laboratory of Electronics (RLE) and member of the Quantum Engineering group at MIT; and Paola Cappellaro, a professor in the Department of Nuclear Science and Engineering, a member of RLE, and head of the Quantum Engineering group at MIT.

Characterizing defects

NV centers occur where carbon atoms in two adjacent places in a diamond’s lattice structure are missing — one atom is replaced by a nitrogen atom, and the other space is an empty “vacancy.” The NV center essentially functions as an atom, with a nucleus and surrounding electrons that are extremely sensitive to tiny variations in surrounding electrical, magnetic, and optical fields. Sweeping microwaves across the center, for instance, makes it change, and thus control, the spin states of the nucleus and electrons.

Spins are measured using a type of magnetic resonance spectroscopy. This method plots the frequencies of electron and nucleus spins in megahertz as a “resonance spectrum” that can dip and spike, like a heart monitor. Spins of an NV center under certain conditions are well-known. But the surrounding spin defects are unknown and difficult to characterize.

In their work, the researchers identified, located, and controlled two electron-nuclear spin defects near an NV center. They first sent microwave pulses at specific frequencies to control the NV center. Simultaneously, they pulse another microwave that probes the surrounding environment for other spins. They then observed the resonance spectrum of the spin defects interacting with the NV center.

The spectrum dipped in several spots when the probing pulse interacted with nearby electron-nuclear spins, indicating their presence. The researchers then swept a magnetic field across the area at different orientations. For each orientation, the defect would “spin” at different energies, causing different dips in the spectrum. Basically, this allowed them to measure each defect’s spin in relation to each magnetic orientation. They then plugged the energy measurements into a model equation with unknown parameters. This equation is used to describe the quantum interactions of an electron-nuclear spin defect under a magnetic field. Then, they could solve the equation to successfully characterize each defect.

Locating and controlling

After characterizing the defects, the next step was to characterize the interaction between the defects and the NV, which would simultaneously pinpoint their locations. To do so, they again swept the magnetic field at different orientations, but this time looked for changes in energies describing the interactions between the two defects and the NV center. The stronger the interaction, the closer they were to one another. They then used those interaction strengths to determine where the defects were located, in relation to the NV center and to each other. That generated a good map of the locations of all three defects in the diamond.

Characterizing the defects and their interaction with the NV center allow for full control, which involves a few more steps to demonstrate. First, they pump the NV center and surrounding environment with a sequence of pulses of green light and microwaves that help put the three qubits in a well-known quantum state. Then, they use another sequence of pulses that ideally entangles the three qubits briefly, and then disentangles them, which enables them to detect the three-spin coherence of the qubits.

The researchers verified the three-spin coherence by measuring a major spike in the resonance spectrum. The measurement of the spike recorded was essentially the sum of the frequencies of the three qubits. If the three qubits for instance had little or no entanglement, there would have been four separate spikes of smaller height.

“We come into a black box [environment with each NV center]. But when we probe the NV environment, we start seeing dips and wonder which types of spins give us those dips. Once we [figure out] the spin of the unknown defects, and their interactions with the NV center, we can start controlling their coherence,” Sun says. “Then, we have full universal control of our quantum system.”

Next, the researchers hope to better understand other environmental noise surrounding qubits. That will help them develop more robust error-correcting codes for quantum circuits. Furthermore, because on average the process of NV center creation in diamond creates numerous other spin defects, the researchers say they could potentially scale up the system to control even more qubits. “It gets more complex with scale. But if we can start finding NV centers with more resonance spikes, you can imagine starting to control larger and larger quantum systems,” Sun says.

The Pitfalls of Overreliance on the Quantum Volume Metric

dougfinke1 — Fri, 06 Mar 2020 01:00:10 +0000

The metric Quantum Volume (QV) has been in the news lately and it deserves a few more words of explanation. This metric was first created by IBM in 2017 and modified in 2018 as a metric that would allow comparison of different quantum computers. It has many valuable characteristics. It is a well-documented, straightforward way of comparing different quantum computers that can be run on any gate level quantum computer, not just ones that use a superconducting technology. Most important, it considers qubit count, qubit quality and other factors so it does not emphasize the number of qubits alone. It is a good tool for use by quantum hardware engineers to measure their progress in development. If they are able to come up with a new generation of hardware that increases this metric, they are going in the right direction. However, it is a poor tool for end users to use if they want to measure the goodness of a quantum computer for solving their computation problems.

We will explain why Quantum Volume is not really appropriate for end users in this brief. But first, we will provide a simplified explanation of how this measure is derived. The quantum volume measurement involves testing a series of circuits with a square configuration. By that, we mean that the number of qubits equals the gate depth of the circuit. For example, a test may begin by trying out a 2×2 configuration. This would mean a 2 qubit circuit with each gate going through 2 gate levels. In these tests, the gate sequences are alternating sequences of single qubit gates followed by two qubit gates. The circuit is run multiple times with the results measured and the results are analyzed with a certain statistical test to see how accurate the answer is to what would be the theoretical result. If the test passes a certain criteria, then the test is repeated for a 3×3 configuration, a 4×4 configuration, etc. Because qubits are imperfect, each increased level gets harder and harder because the gate errors start stacking up and the test no longer passes the criteria. Once the largest square array is found that will pass the test, the Quantum Volume is calculated as 2ⁿ where n is the number of qubits and gate depth. So a 4×4 circuit would have a QV of 16, a 5×5 circuit would have a QV of 32, a 6×6 circuit would have a QV of 64, etc. For complete details on how this test is conducted, we refer you to the paper that IBM posted on arXiv.

Here are our concerns about Quantum Volume:

The test is all based upon a square circuit configuration, but very few quantum programs really have a square configuration. Some of the algorithms being developed for NISQ computers such as VQE and QAOA, are wide and shallow. This means that use a larger number of qubits but only a few levels of gate depth. Others, may have a much larger number of gate operations versus the numbers of qubits. For example, Shor’s algorithm can theoretically factor a 2048 bit number using about 4100 logical qubits, but it requires about 8.6×10⁹ gate operations. (Note that is based upon logical or error-free qubits and not physical qubits).
We do not agree with calculating the quantum volume by using a formula of 2ⁿ. We think this gives a distorted view of how fast the quantum computer performance is increasing. Let us explain this by an analogy. Let’s suppose we were looking for office space and the landlord shows us two offices spaces with dimensions 5×5 or 6×6. (You can use either feet or meters as the dimension depending upon what country you are in.) Would you expect to pay twice as much for the 6×6 office as the 5×5 office? No! You could calculate the worth by looking at the square area and determine that the 6×6 is about 44% more valuable (36/25) than the 5×5, not 100%. In a quantum computing algorithm, we do not think an end user would be able to increase their problem size by 100% if they were provided a new quantum computer that had just one more qubit and one more gate level.
The focus for anyone developing a quantum computer should be how to make it achieve quantum advantage and solve problems better than a classical computer. Since classical computers are error free, the equivalent quantum volume for a quantum program running on a quantum simulator on a classical computer can be very high. For example, in 2019, Google ran a quantum benchmark on the Summit supercomputer at the Oak Ridge National Lab that successfully calculated the results of a 49×40 circuit. So the equivalent QV for Summit would be 2⁴⁰ or about 1.1 x 10¹².

So for anyone claiming to have the world’s highest performance quantum computer, a high Quantum Volume figure is helpful, but we would not regard it as definitive proof. Perhaps a more appropriate challenge would be to replicate or beat Google’s Quantum Supremacy experiment. At this point in time, anyone who can achieve that would indeed have something noteworthy.

March 5, 2020

C2ST presents “Quantum Computing” with Fermilab speakers Joe Lykken, Farah Fahim – March 25

leah — Thu, 05 Mar 2020 22:44:19 +0000

Mark your calendars: On Wednesday, March 25, the Chicago Council on Science and Technology presents “Quantum Computing,” featuring Fermilab Deputy Director for Research Joe Lykken and Fermilab Deputy Head of Quantum Science Farah Fahim. Northwestern University’s Prem Kumar is also a featured guest.

Quantum computing could spur the development of new breakthroughs in science, medications to save lives, machine learning methods to diagnose illnesses sooner, materials to make more efficient devices and structures, financial strategies to live well in retirement, and algorithms to quickly direct resources such as ambulances.

Wednesday, March 25, 6-7:30 p.m.
Hughes Auditorium, Robert H. Lurie Building, Northwestern Chicago Campus
303 E Superior St, Chicago, Illinois

Learn more and register.

Turn down the quantum volume

Scott — Thu, 05 Mar 2020 21:36:59 +0000

Several people asked me to comment on the recent announcement by Honeywell that they’ll soon have what they call “the most powerful” quantum computer (see here for press release, here for Forbes article, here for paper).

I’m glad that Honeywell, which many people might know as an air-conditioner manufacturer, has entered the race for trapped-ion QC. I wish them success. I’ve known about what they were doing in part because Drew Potter, my friend and colleague in UT Austin’s physics department, took a one-year leave from UT to contribute to their effort.

Here I wanted to comment about one detail in Honeywell’s announcement: namely, the huge emphasis on “quantum volume” as the central metric for judging quantum computing progress, and the basis for calling their own planned device the “most powerful.” One journalist asked me to explain why quantum volume is such an important measure. I had to give her an honest answer: I don’t know whether it is.

Quantum volume was invented a few years ago by a group at IBM. According to one of their papers, it can be defined roughly as 2^k, where k is the largest number such that you can run a k-qubit random quantum circuit, with depth k and with any-to-any connectivity, and have at least (say) 2/3 probability of measuring an answer that passes some statistical test. (In the paper, they use what Lijie Chen and I called Heavy Output Generation, though Google’s Linear Cross-Entropy Benchmark is similar.)

I don’t know why IBM takes the “volume” to be 2^k rather than k itself. Leaving that aside, though, the idea was to invent a single “goodness measure” for quantum computers that can’t be gamed either by building a huge number of qubits that don’t maintain nearly enough coherence (what one might call “the D-Wave approach”), or by building just one perfect qubit, or by building qubits that behave well in isolation but don’t interact easily. Note that the any-to-any connectivity requirement makes things harder for architectures with nearest-neighbor interactions only, like the 2D superconducting chips being built by Google, Rigetti, or IBM itself.

You know the notion of a researcher’s h-index—defined as the largest h such that she’s published h papers that garnered h citations each? Quantum volume is basically an h-index for quantum computers. It’s an attempt to take several different yardsticks of experimental progress, none terribly useful in isolation, and combine them into one “consumer index.”

Certainly I sympathize with the goal of broadening people’s focus beyond the “but how many qubits does it have?” question—since the answer to that question is meaningless without further information about what the qubits can do. From that standpoint, quantum volume seems like a clear step in the right direction.

Alas, Goodhart’s Law states that “as soon as a measure becomes a target, it ceases to be a good measure.” That happened years ago with the h-index, which now regularly pollutes academic hiring and promotion decisions, to the point where its inventor expressed regrets. Quantum volume is now looking to me like another example of Goodhart’s Law at work.

The position of Honeywell’s PR seems to be that, if they can build a device that can apply 6 layers of gates to 6 qubits, with full connectivity and good fidelity, that will then count as “the world’s most powerful quantum computer,” since it will have the largest volume. One problem here is that such a device could be simulated by maintaining a vector of only 2⁶=64 amplitudes. This is nowhere near quantum supremacy (i.e., beating classical computers at some well-defined task), which is a necessary though not sufficient condition for doing anything useful.

Think of a university that achieves an average faculty-to-student ratio of infinity by holding one class with zero students. It gets the “best score” only by exploiting an obvious defect in the scoring system.

So what’s the alternative? The policy that I prefer is simply to tell the world all your system specs, as clearly as you can, with no attempts made to bury the lede. How many qubits do you have? With what coherence times? With what connectivity? What are the 1- and 2-qubit gate fidelities? What depth of circuit can you do? What resources do the standard classical algorithms need to simulate your system? Most importantly: what’s the main drawback of your system, the spec that’s the least good, that you most need to improve? What prevents you from having a scalable quantum computer right now? And are you going to tell me in your public announcement, or will you make me search in Appendix III.B of your paper, or worse yet, ask one of your competitors?

I confess that the answers to the above questions are harder to summarize in a single number (unless we, like, concatenated binary encodings of the answers or something). But they can be ineffably combined, to produce a progress metric that one of my postdocs suggested calling “quantum scottness,” and which roughly equals the number of expressions of wide-eyed surprise minus the number of groans.

A talented 2D material gets a new gig

Wed, 04 Mar 2020 19:15:29 +0000

Scientists have designed a tunable graphene device for experiments in exotic physics, where superconducting, insulating, and magnetic properties can be observed in a single system. The technology could advance the development of next-generation memory devices and quantum computers.

Using molecules to draw on quantum materials

Wed, 04 Mar 2020 19:14:22 +0000

Over millennia, civilizations progressed through the Stone, Bronze, and Iron Ages. Now the time has come for quantum materials to change the way we live, researchers say.

Honeywell Discloses their QC Roadmap and Investments in Zapata and Cambridge Quantum Computing

dougfinke1 — Wed, 04 Mar 2020 06:12:31 +0000

In a news release and two different blog articles and technical papers, Honeywell has provided some details on their ion trap quantum architecture that they have dubbed QCCD (quantum charge coupled device). They have indicated that they will be introducing within the next 3 months a quantum computer with a Quantum Volume measure of 64 or greater which would double the current quantum volume measure recently announced by IBM in their latest quantum computer. Moreover, they described a goal to increase this measure by an order of magnitude per year for the next several years, which would certainly beat out IBM’s stated goal of doubling their quantum volume every year. We should also note that not everyone within the quantum community agrees that quantum volume is the best measure for comparing the performance of different quantum machines, nor has anyone besides IBM and Honeywell used this metric when describing the performance of their machines.

In a technical paper, Honeywell describes the design in more detail and includes some qubit benchmarking results which look quite good. (We have already added Honeywell’s data to our Qubit Quality tables so you can compare their metrics versus some other designs.) Honeywell did not disclose the number of qubits they will have in the machine that will be released later this year, but we will point it that is feasible to create a design with a quantum volume of 64 with as few as 6 very high quality qubits. Their technical paper also did not mention gate delays or coherence times for their design. Typically, ion trap machines have gate delays which are orders of magnitude worse than superconducting designs, but also have coherence times which are orders of magnitude better.

Honeywell also announced that one of their first commercial customers will be JPMorgan Chase. This is interesting because JPMorgan Chase is also one of IBM’s industry partners in their IBM Q Network. So JPMorgan Chase will be in a good position to compare the two platforms.

It appears that Honeywell will rely upon partners to provide software support rather than developing their own like some of the other quantum hardware vendors. Their investment in Zapata and Cambridge Quantum Computing (CQC) will certainly help this. Both software companies have professed a philosophy of developing hardware agnostic software platforms that can accommodate a variety of platforms so they will surely have support for the Honeywell hardware in the future. And since Honeywell is partnering with Microsoft Azure to provide cloud access to their machines, it’s a safe bet that their hardware will also be supported by Microsoft’s Q# quantum programming language.

For more information about Honeywell’s efforts, you can read their press release here, their two blog articles here and here, and their technical paper here.

A coronavirus poem

Scott — Wed, 04 Mar 2020 02:13:12 +0000

These next few months, every time I stop myself from touching my face by force of will,

Let me remind myself that the same willpower is available to diet, to exercise, to throw myself into a project, to keep calm amid screaming, to introduce myself to strangers, to decrease the fraction of my life spent getting upset that someone was mean to my ingroup on social media, or otherwise to better myself as a human specimen.

Yea, let all of these things be just as easy for me as it was not to touch my face.

Ah, but what if I forget, what if I do keep touching my face in the next few months?

In one plausible scenario, with at least ~0.1% probability and probably higher depending on my age, a cheap answer will be available to that question: namely, that I’ll no longer be around to ponder the implications.

Paperz

Scott — Tue, 03 Mar 2020 18:03:12 +0000

Soon, all anyone will want to talk about is quarantines, food shortages, N95 masks, the suspension of universities and of scientific conferences. (As many others have pointed out, this last might actually be a boon to scientific productivity—as it was for a young Isaac Newton when Cambridge was closed for the bubonic plague, so Newton went home and invented calculus and mechanics.)

Anyway, before that all happens, I figured I’d get in a last post about quantum information and complexity theory progress.

Hsin-Yuan Huang, Richard Kueng, and John Preskill have a nice preprint entitled Predicting Many Properties of a Quantum System from Very Few Measurements. In it they take shadow tomography, which I proposed a couple years ago, and try to bring it closer to practicality on near-term devices, by restricting to the special case of non-adaptive, one-shot measurements, on separate copies of the state ρ that you’re trying to learn about. They show that this is possible using a number of copies that depends logarithmically on the number of properties you’re trying to learn (the optimal dependence), not at all on the Hilbert space dimension, and linearly on a new “shadow norm” quantity that they introduce.

Rahul Ilango, Bruno Loff, and Igor Oliveira announced the pretty spectacular-sounding result that the Minimum Circuit Size Problem (MCSP) is NP-complete for multi-output functions—that is, for Boolean functions f with not only many input bits but many outputs. Given the 2ⁿ-sized truth table of a Boolean function f:{0,1}ⁿ→{0,1}, the original MCSP simply asks for the size of the smallest Boolean circuit that computes f. This problem was studied in the USSR as early as the 1950s; whether it’s NP-complete has stood for decades as one of the big open problems of complexity theory. We’ve known that if you could quickly solve MCSP then you could also invert any one-way function, but we’ve also known technical barriers to going beyond that to a flat-out NP-hardness result, at least via known routes. Before seeing this paper, I’d never thought about whether MCSP for many-output functions might somehow be easier to classify, but apparently it is!

Hamoon Mousavi, Seyed Nezhadi, and Henry Yuen have now taken the MIP*=RE breakthrough even a tiny step further, by showing that “zero-gap MIP*” (that is, quantum multi-prover interactive proofs with an arbitrarily small gap between the completeness and soundness probabilities) takes you even beyond the halting problem (i.e., beyond Recursively Enumerable or RE), and up to the second level of the arithmetical hierarchy (i.e., to the halting problem for Turing machines with oracles for the original halting problem). This answers a question that someone asked in the comments section of this blog.

Several people asked me for comment on the paper What limits the simulation of quantum computers?, by Yiqing Zhou, Miles Stoudenmire, and Xavier Waintal. In particular, does this paper refute or weaken Google’s quantum supremacy claim, as the paper does not claim to do (but, rather coyly, also does not claim not to do)? Short answer: No, it doesn’t, or not now anyway.

Longer, more technical answer: The quoted simulation times, just a few minutes for quantum circuits with 54 qubits and depth 20, assume Controlled-Z gates rather than iSWAP-like gates. Using tensor network methods, the classical simulation cost with the former is roughly the square root of the simulation cost with the latter (~2^k versus ~4^k for some parameter k related to the depth). As it happens, Google switched its hardware from Controlled-Z to iSWAP-like gates a couple years ago precisely because they realized this—I had a conversation about it with Sergio Boixo at the time. Once this issue is accounted for, the quoted simulation times in the new paper seem to be roughly in line with what was previously reported by, e.g., Johnnie Gray and Google itself.

To end with a community announcement: as many of you might know, the American Physical Society’s March Meeting, which was planned for this week in Denver, was abruptly cancelled due to the coronavirus (leaving thousands of physicists out their flights and hotel rooms—many had even already arrived there). However, my colleague Michael Biercuk kindly alerted me to a “virtual March Meeting” that’s been set up online, with recorded talks and live webinars. Even after the pandemic passes, is this a model that we should increasingly move to? I wouldn’t have thought so ten or fifteen years ago, but today every schlep across the continent brings me a step closer to shoting “yes”…

How a new quantum approach can develop faster algorithms to deduce complex networks

Tue, 03 Mar 2020 16:34:00 +0000

Complex networks are ubiquitous in the real world, from artificial to purely natural ones, and they exhibit very similar geometric properties. Algorithms based on quantum mechanics perform well on such networks, but their relationship with the geometrical characteristics of networks has remained unclear until now. Researchers have now shed light on these relationships, opening up new possibilities for the use of complex networks in various fields.

Atomic vacancy as quantum bit

Mon, 02 Mar 2020 16:49:46 +0000

Physicists have experimentally observed spin centers in two-dimensional materials. Such centers can act as quantum bits -- even at room temperature.

KITE code could power new quantum developments

Mon, 02 Mar 2020 16:33:49 +0000

A research collaboration has created open-source software to assist in the creation of quantum materials which could in turn vastly increase the world's computing power.

Measuring electron spin qubit without demolishing it

Mon, 02 Mar 2020 16:33:10 +0000

Scientists have succeeded in taking repeated measurements of the spin of an electron in a silicon quantum dot (QD), without changing the spin in the process. This type of 'non-demolition' measurement is important for creating quantum computers that are fault tolerant.

Freeman Dyson and Boris Tsirelson

Scott — Sat, 29 Feb 2020 13:53:37 +0000

Today, as the world braces for the possibility of losing millions of lives to the new coronavirus—to the hunger for pangolin meat, of all things—we also mourn the loss of two incredibly special lives, those of Freeman Dyson (age 96) and Boris Tsirelson (age 69).

Freeman Dyson was sufficiently legendary, both within and beyond the worlds of math and physics, that there’s very little I can add to what’s been said. It seemed like he was immortal, although I’d heard from mutual friends that his health was failing over the past year. When I spent a year as a postdoc at the Institute for Advanced Study, in 2004-5, I often sat across from Dyson in the common room, while he drank tea and read the news. That I never once struck up a conversation with him is a regret that I’ll now carry with me forever.

My only exchange with Dyson came when he gave a lecture at UC Berkeley, about how life could persist arbitrarily far into the future, even after the last stars had burnt out, by feeding off steadily dimishing negentropy flows in the nearly-thermal radiation. During the Q&A, I challenged Dyson that his proposal seemed to assume an analog model of computation. But, I asked, once we took on board the quantum-gravity insights of Jacob Bekenstein and others, suggesting that nature behaves like a (quantum) digital computer at the Planck scale, with at most ~10⁴³ operations per second and ~10⁶⁹ qubits per square meter and so forth, wasn’t this sort of proposal ruled out? “I’m not going to argue with you,” was Dyson’s response. Yes, he’d assumed an analog computational model; if computation was digital then that surely changed the picture.

Sometimes—and not just with his climate skepticism, but also (e.g.) with his idea that general relativity and quantum mechanics didn’t need to be reconciled, that it was totally fine for the deepest layer of reality to be a patchwork of inconsistent theories—Dyson’s views struck me as not merely contrarian but as a high-level form of trolling. Even so, Dyson’s book Disturbing the Universe had had a major impact on me as a teenager, albeit for the sparkling prose as much as for the ideas.

With Dyson’s passing, the scientific world has lost one of its last direct links to a heroic era, of Einstein and Oppenheimer and a young Richard Feynman, when theoretical physics stood at the helm of human civilization like never before or since. Dyson, who apparently remained not only lucid but mathematically powerful (!) well into his last year, clearly remembered when the Golden Age of science fiction looked like simply sober forecasting; when the smartest young people, rather than denouncing each other on Twitter, dreamed of scouting the solar system in thermonuclear-explosion-powered spacecraft and seriously worked to make that happen.

Boris Tsirelson (homepage, Wikipedia), who emigrated from the Soviet Union and then worked at Tel Aviv University (where my wife Dana attended his math lectures), wasn’t nearly as well known as Dyson to the wider world, but was equally beloved within the quantum computing and information community. Tsirelson’s bound, which he proved in the 1980s, showed that even quantum mechanics could only violate the Bell inequality by so much and by no more, could only let Alice and Bob win the CHSH game with probability cos²(π/8). This seminal result anticipated many of the questions that would only be asked decades later with the rise of quantum information. Tsirelson’s investigations of quantum nonlocality also led him to pose the famous Tsirelson’s problem: loosely speaking, can all sets of quantum correlations that can arise from an infinite amount of entanglement, be arbitrarily well approximated using finite amounts of entanglement? The spectacular answer—no—was only announced one month ago, as a corollary of the MIP*=RE breakthrough, something that Tsirelson happily lived to see although I don’t know what his reaction was. Sadly, for some reason, I never met Tsirelson in person, although I did have lively email exchanges with him 10-15 years ago about his problem and other topics. This amusing interview with Tsirelson gives some sense for his personality (hat tip to Gil Kalai, who knew Tsirelson well).

Ultrafast probing reveals intricate dynamics of quantum coherence

Fri, 28 Feb 2020 19:20:20 +0000

Ultrafast, multidimensional spectroscopy unlocks macroscopic-scale effects of quantum electronic correlations. Researchers found that low-energy and high energy states are correlated in a layered, superconducting material. Exciting the material with an ultrafast beam of near-infrared light produces coherent excitations lasting a surprisingly 'long' time of around 500 femtoseconds, originating from a quantum superposition of excited states within the crystal.

President Reif testifies before Congress on U.S. competitiveness

MIT News Office — Thu, 27 Feb 2020 20:53:46 +0000

No U.S. strategy to respond to competition from China will succeed unless it includes increased investment in research, a concerted effort to attract more students to key research fields, and a more creative approach to turning ideas into commercial products, MIT President L. Rafael Reif said in congressional testimony on Wednesday, Feb. 26.

Reif spoke at a hearing of the House Ways and Means Committee on “U.S.-China Trade and Competition.”

“Whatever else the U.S. does to counter the challenges posed by China, we must increase our investment in research in key technology areas, and we must enhance our capacity to get the most out of that investment,” he told the panel. “U.S. strategy is unlikely to succeed if it is merely defensive; to stay ahead, the U.S. needs to do more to capitalize on our own strengths.”

Reif’s Capitol Hill appearance came immediately after he delivered an opening talk at a National Academy of Sciences (NAS)_event commemorating the 75th anniversary of “Science, The Endless Frontier,” a 1945 report to U.S. President Harry S. Truman that is seen as the founding document of the post-World War II research system in the U.S. The report was written by the late Vannevar Bush, who had a long career at MIT, including service as the Institute’s vice president and dean of engineering.

At both the NAS and on Capitol Hill, Reif called for a “visible, focused, and sustained” federal program that would increase funding for research and target the increase at key technologies, such as artificial intelligence, quantum computing, and advanced communications.

“The U.S. lacks an effective, coordinated way to target research toward specific areas and funding has fallen far behind what’s needed to stay ahead of our competitors,” Reif told Congress. “One promising proposal is to create a new directorate at the National Science Foundation with that mission, and giving that new unit the authority to be run more like the Defense Advanced Research Projects Agency (DARPA).”

Reif also said that attracting top talent is another essential element of a successful strategy. “At the university level, that requires two parallel tasks — attracting top U.S. students to key fields, and attracting and retaining the best researchers from around the world,” he said.

Specifically, he called for new programs to offer federal support to undergraduates, graduate students, and postdocs who are willing to study in fields related to key technologies. He also said foreign students who receive a U.S. doctorate should immediately be given a green card to settle in the U.S., and he warned against anti-immigrant rhetoric.

Finally, Reif said the U.S. needs to experiment with ways to speed the transition of ideas from lab to market. He called for new ways to de-risk technologies and to create more patient capital, and suggested that the Ways and Means Committee, which has jurisdiction over tax policy, should look at tax policies to create incentives for longer-term investment and to foster more university-industry cooperation.

“The U.S. edge in science and technology has been a foundation for U.S. security, prosperity, and quality of life,” Reif said, in conclusion. “But that edge has to be regularly honed; it is not ours by right or by nature. We can best sharpen it with a strategy founded on confidence in ourselves, not fear of others.”

Two weeks ago, Vice President for Research Maria Zuber delivered a similar message to Congress, in testimony before the House Permanent Select Committee on Intelligence on how to improve the intelligence services’ access to science and technology.

Zuber said that to help the intelligence services, the U.S. needs to capitalize on its strengths, which she said include “world-class universities, an open research system, and the ability to attract and retain top talent from around the world.”

Like Reif, Zuber highlighted a proposal to create a new technology directorate at the National Science Foundation, as well as the need to attract talent domestically and from abroad. She also cited MIT’s AI Accelerator — a cooperative project between MIT and the U.S. Air Force — as the kind of cooperative work that the intelligence services could foster.

In her testimony, Zuber emphasized the need to maintain an open U.S. research system: “The U.S. faces new challenges and competitors,” she said, “but we are well-placed to succeed if we get the most from our unrivaled strengths.”

Quantum researchers able to split one photon into three

Thu, 27 Feb 2020 17:21:19 +0000

Researchers report the first occurrence of directly splitting one photon into three. The occurrence, the first of its kind, used the spontaneous parametric down-conversion method (SPDC) in quantum optics and created what quantum optics researchers call a non-Gaussian state of light. A non-Gaussian state of light is considered a critical ingredient to gain a quantum advantage.

Des chercheurs en physique quantique parviennent à diviser un photon en trois

12011 — Thu, 27 Feb 2020 00:00:00 +0000

Thursday, February 27, 2020

In English.

Des chercheurs de l’Institut d’informatique quantique (IQC) de l’Université de Waterloo rapportent la première subdivision directe d’un photon en trois.