Quantum

Classiq and Quantum Intelligence Corp (QIC) Collaborate on Quantum Accelerated Drug Development

Mohamed Abdel-Kareem — Thu, 04 Apr 2024 23:35:11 +0000

Classiq, a leading quantum computing software company, has partnered with Quantum Intelligence Corp. (QIC, Korea) to accelerate drug development through quantum computing applications in pharmacology. Under Classiq’s Quantum Computing For Life Sciences & Healthcare Center, established with NVIDIA, the collaboration aims to enhance drug discovery, design, and prediction of side effects using quantum computing. QIC, [...]

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Understanding the realistic limits of security for quantum key distribution

Elizabeth Kleisath — Thu, 04 Apr 2024 00:00:00 +0000

Thursday, April 4, 2024

A commonly researched method of quantum cryptography is quantum key distribution (QKD). In this method, quantum states are used to generate secret keys which can then be used for secure communication between two users. Due to the fundamental principles of quantum mechanics, the QKD protocols produce keys that can be guaranteed as secure from eavesdroppers, thus also ensuring the security of the subsequent communication using the secret keys.

And yet quantum computing continues to progress

Scott — Wed, 03 Apr 2024 17:28:59 +0000

Pissing away my life in a haze of doomscrolling, sporadic attempts to “parent” two rebellious kids, and now endless conversations about AI safety, I’m liable to forget for days that I’m still mostly known (such as I am) as a quantum computing theorist, and this blog is still mostly known as a quantum computing blog. Maybe it’s just that I spent a quarter-century on quantum computing theory. As an ADHD sufferer, anything could bore me after that much time, even one of the a-priori most exciting things in the world.

It’s like, some young whippersnappers proved another monster 80-page theorem that I’ll barely understand tying together the quantum PCP conjecture, area laws, and Gibbs states? Another company has a quantum software platform, or hardware platform, and they’ve issued a press release about it? Another hypester claimed that QC will revolutionize optimization and machine learning, based on the usual rogues’ gallery of quantum heuristic algorithms that don’t seem to outperform classical heuristics? Another skeptic claimed that scalable quantum computing is a pipe dream—mashing together the real reasons why it’s difficult with basic misunderstandings of the fault-tolerance theorem? In each case, I’ll agree with you that I probably should get up, sit at my laptop, and blog about it (it’s hard to blog with two thumbs), but as likely as not I won’t.

And yet quantum computing continues to progress. In December we saw Harvard and QuEra announce a small net gain from error-detection in neutral atoms, and accuracy that increased with the use of larger error-correcting codes. Today, a collaboration between Microsoft and Quantinuum has announced what might be the first demonstration of error-corrected two-qubit entangling gates with substantially lower error than the same gates applied to the bare physical qubits. (This is still at the stage where you need to be super-careful in how you phrase every such sentence—experts should chime in if I’ve already fallen short; I take responsibility for any failures to error-correct this post.)

You can read the research paper here, or I’ll tell you the details to the best of my understanding (I’m grateful to Microsoft’s Krysta Svore and others from the collaboration for briefing me by Zoom). The collaboration used a trapped-ion system with 32 fully-connected physical qubits (meaning, the qubits can be shuttled around a track so that any qubit can directly interact with any other). One can apply an entangling gate to any pair of qubits with ~99.8% fidelity.

What did they do with this system? They created up to 4 logical encoded qubits, using the Steane code and other CSS codes. Using logical CNOT gates, they then created logical Bell pairs — i.e., (|00⟩+|11⟩)/√2 — and verified that they did this.

That’s in the version of their experiment that uses “preselection but not postselection.” In other words, they have to try many times until they prepare the logical initial states correctly—as with magic state factories. But once they do successfully prepare the initial states, there’s no further cheating involving postselection (i.e., throwing away bad results): they just apply the logical CNOT gates, measure, and see what they got.

For me personally, that’s the headline result. But then they do various further experiments to “spike the football.” For one thing, they show that when they do allow postselected measurement outcomes, the decrease in the effective error rate can be much much larger, as large as 800x. That allows them (again, under postselection!) to demonstrate up to two rounds of error syndrome extraction and correction while still seeing a net gain, or three rounds albeit with unclear gain. The other thing they demonstrate is teleportation of fault-tolerant qubits—so, a little fancier than just preparing an encoded Bell pair and then measuring it.

They don’t try to do (e.g.) a quantum supremacy demonstration with their encoded qubits, like Harvard/QuEra did—they don’t have nearly enough qubits for that. But this is already extremely cool, and it sets a new bar in quantum error-correction experiments for others to meet or exceed (superconducting, neutral atom, and photonics people, that means you!). And I wasn’t expecting it! Indeed, I’m so far behind the times that I still imagined Microsoft as committed to a strategy of “topological qubits or bust.” While Microsoft is still pursuing the topological approach, their strategy has clearly pivoted over the last few years towards “whatever works.”

Anyway, huge congratulations to the teams at Microsoft and Quantinuum for their accomplishment!

Stepping back, what is the state of experimental quantum computing, 42 years after Feynman’s lecture, 30 years after Shor’s algorithm, 25 years after I entered the field, 5 years after Google’s supremacy experiment? There’s one narrative that quantum computing is already being used to solve practical problems that couldn’t be solved otherwise (look at all the hundreds of startups! they couldn’t possibly exist without providing real value, could they?). Then there’s another narrative that quantum computing has been exposed as a fraud, an impossibility, a pipe dream. Both narratives seem utterly disconnected from the reality on the ground.

If you want to track the experimental reality, my one-sentence piece of advice would be to focus relentlessly on the fidelity with which experimenters can apply a single physical 2-qubit gate. When I entered the field in the late 1990s, ~50% woud’ve been an impressive fidelity. At some point it became ~90%. With Google’s supremacy experiment in 2019, we saw 1000 gates applied to 53 qubits, each gate with ~99.5% fidelity. Now, in superconducting, trapped ions, and neutral atoms alike, we’re routinely seeing ~99.8% fidelities, which is what made possible (for example) the new Microsoft/Quantinuum result. The best fidelities I’ve heard reported this year are more like ~99.9%.

Meanwhile, on paper, it looks like known methods for quantum fault-tolerance, for example using the surface code, should start to become practical once you have 2-qubit fidelities around ~99.99%—i.e., one more “9” from where we are now. And then there should “merely” be the practical difficulty of maintaining that 99.99% fidelity while you scale up to millions or hundreds of millions of physical qubits!

What I’m trying to say is: this looks a pretty good trajectory! It looks like, if we plot the infidelity on a log scale, the experimentalists have already gone three-quarters of the distance. It now looks like it would be a surprise if we couldn’t have hundreds of fault-tolerant qubits and millions of gates on them within the next decade, if we really wanted that—like something unexpected would have to go wrong to prevent it.

Wouldn’t be ironic if all that was true, but it will simply matter much less than we hoped in the 1990s? Either just because the set of problems for which a quantum computing is useful has remained stubbornly more specialized than the world wants it to be (for more on that, see the entire past 20 years of this blog) … or because advances in classical AI render what was always quantum computing’s most important killer app, to the simulation of quantum chemistry and materials, increasingly superfluous (as AlphaFold may have already done for protein folding) … or simply because civilization descends further into barbarism, or the unaligned AGIs start taking over, and we all have bigger things to worry about than fault-tolerant quantum computing.

But, you know, maybe fault-tolerant quantum computing will not only work, but matter—and its use to design better batteries and drugs and photovoltaic cells and so on will pass from science-fiction fantasy to quotidian reality so quickly that much of the world (weary from the hypesters crying wolf too many times?) will barely even notice it when it finally happens, just like what we saw with Large Language Models a few years ago. That would be worth getting out of bed for.

Quantinuum and Microsoft Reach New Milestone for Fault Tolerant Quantum Computing

dougfinke — Wed, 03 Apr 2024 14:59:23 +0000

Chart Showing Improvement in Error Rates with this Latest Research. Credit: Quantinuum The race to achieve fault tolerant quantum computing (FTQC) will need many steps in order to cross the goal line and provide a usable capability so that end users can take advantage of it for their applications. But Quantinuum and Microsoft have moved [...]

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Quantum Computing Inc. Releases Full Year 2023 Financial Report

dougfinke — Wed, 03 Apr 2024 03:22:46 +0000

For the full year of 2023, the company achieved revenue of $358 thousand versus revenue of $136 thousand in 2022. Net loss was Net loss was $29.73 million versus a 2022 loss of $38.59 million a year ago. The company ended the year with cash of about $2.06 million versus $5.308 million in 2022. Their [...]

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100 kilometers of quantum-encrypted transfer

Tue, 02 Apr 2024 18:01:11 +0000

Researchers have taken a big step towards securing information against hacking. They have succeeded in using quantum encryption to securely transfer information 100 kilometers via fiber optic cable -- roughly equivalent to the distance between Oxford and London.

SoftwareQ, Dr. Michele Mosca and Dr. Vlad Gheorghiu begin new partnership with Nu Quantum for fault-tolerant quantum computing

Elizabeth Kleisath — Mon, 01 Apr 2024 00:00:00 +0000

Monday, April 1, 2024

SoftwareQ, a company founded by Dr. Michele Mosca, IQC faculty member and professor in the Department of Combinatorics and Optimization at the University of Waterloo, and Dr. Vlad Gheorghiu, IQC affiliate member and alumnus, has been awarded up to $419,200 in funding for a new collaboration with Nu Quantum, a leading quantum networking company in the United Kingdom.

IBM Publishes Their Paper on qLDPC Codes and Will Be Retiring Their Cloud Simulators

dougfinke — Sat, 30 Mar 2024 20:20:21 +0000

Nature Magazine Cover of the Issue with IBM's aLDPC Paper Showing the Torus Topologies Used in this Code. Credit: IBM IBM's Research in qLDPC Codes The popular press is buzzing with IBM's announcement that they have published an article about the research of qLDPC (Quantum Low Density Parity Check) codes in Nature magazine. But attentive [...]

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SandboxAQ Announces General Availability of Its AQtive Guard Platform to Protect Against AI-driven and Quantum Attacks

Mohamed Abdel-Kareem — Fri, 29 Mar 2024 21:08:30 +0000

SandboxAQ has unveiled its AQtive Guard platform, designed to tackle the rising threats of AI-driven and Quantum attacks. The platform offers comprehensive cryptography management, enabling enterprises to identify and manage vulnerable cryptographic algorithms and digital keys at an unprecedented scale and granularity. AQtive Guard is the successor to the earlier Sandbox Security Suite product and [...]

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D-Wave Announces Q4 2023 and Full Year 2023 Financial Results

dougfinke — Fri, 29 Mar 2024 19:48:12 +0000

D-Wave Computing Inc. has just reported its Q4 2023 and full year 2023 financial results. While the numbers are important, the highlight of the report for us was that the company now has two customers in regular production usage of their cloud service with two additional ones scheduled to start in a few months. While [...]

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Zapata AI Closes Its Business Combination with Andretti Acquisition Corporation and Will Publicly Trade on the NASDAQ Exchange

dougfinke — Thu, 28 Mar 2024 23:38:17 +0000

Zapata AI, formerly Zapata Computing, has publicly closed its merger with Andretti Acquisition Corporation and will start trading on the NASDAQ exchange with the symbol ZPTA on Monday, April 1, 2024. Zapata originally started as a quantum software company but has branched out to also work in the generative AI area. They still do work [...]

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Quobly Partners with Nanoacademic Technologies to Advance Silicon Spin Qubits for Quantum Computing

Mohamed Abdel-Kareem — Thu, 28 Mar 2024 02:56:37 +0000

Quobly, a French quantum hardware startup developing silicon spin qubit-based quantum computing, has announced a significant partnership with Montreal-based Nanoacademic Technologies, renowned for its digital simulation and modeling tools for quantum technologies. This collaboration aims to enhance Quobly's research and development efforts surrounding silicon spin qubits by leveraging Nanoacademic Technologies' QTCAD® software platform, the world's [...]

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Scaling Quantum Computing: Nu Quantum and SoftwareQ Will Partner to Study Modular Fault Tolerant Quantum Computers

Mohamed Abdel-Kareem — Wed, 27 Mar 2024 23:39:27 +0000

Nu Quantum and SoftwareQ are collaborating to develop the theoretical framework a first fault-tolerant quantum computer, sponsored by Innovate UK under the Canada UK Commercialising Quantum Technology Programme: CR&D and National Research Council of Canada under the Industrial Research Assistance Program (NRC IRAP). The companies have received funding of $1.2 million USD and started the [...]

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Diraq Demonstrates Spin Qubit Operation at 1 Degree Kelvin with Good Qubit Quality Measures

dougfinke — Wed, 27 Mar 2024 21:58:31 +0000

Semiconductor Wafer Containing Spin Qubits. Credit: Diraq Although it may first appear that the difference between operating qubits at 15 millikelvin (0.015K) and 1 kelvin doesn't sound like very much, but for quantum computing it actually makes a world of difference. On one hand, the cooling power of the dilution refrigerators are more than an [...]

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A new type of cooling for quantum simulators

Wed, 27 Mar 2024 16:46:53 +0000

Quantum simulators are quantum systems that can be controlled exceptionally well. They can be used to indirectly learn something about other quantum systems, which cannot be experimented on so easily. Therefore, quantum simulators play an important role in unraveling the big questions of quantum physics. However, they are limited by temperature: They only work well, when they are extremely cold. Scientists have now developed a method to cool quantum simulators even more than before: by splitting a Bose-Einstein-condensate in half, in a very special way.

IQC’s Michael Reimer awarded $1.7 million from Ontario Research Fund

Elizabeth Kleisath — Wed, 27 Mar 2024 00:00:00 +0000

Wednesday, March 27, 2024

En francais

Bullseye! Accurately centering quantum dots within photonic chips

Tue, 26 Mar 2024 16:45:40 +0000

Researchers have now developed standards and calibrations for optical microscopes that allow quantum dots to be aligned with the center of a photonic component to within an error of 10 to 20 nanometers (about one-thousandth the thickness of a sheet of paper). Such alignment is critical for chip-scale devices that employ the radiation emitted by quantum dots to store and transmit quantum information.

Scientists deliver quantum algorithm to develop new materials and chemistry

Mon, 25 Mar 2024 17:50:59 +0000

Scientists published the Cascaded Variational Quantum Eigensolver (CVQE) algorithm in a recent article, expected to become a powerful tool to investigate the physical properties in electronic systems.

The world is one step closer to secure quantum communication on a global scale

Mon, 25 Mar 2024 15:42:06 +0000

Researchers have brought together two Nobel prize-winning research concepts to advance the field of quantum communication. Scientists can now efficiently produce nearly perfect entangled photon pairs from quantum dot sources.

Quantum interference could lead to smaller, faster, and more energy-efficient transistors

Mon, 25 Mar 2024 15:41:29 +0000

Scientists made a single-molecule transistor using quantum interference to control electron flow. This new design offers high on/off ratio and stability, potentially leading to smaller, faster, and more energy-efficient devices. Quantum interference also improves the transistor's sensitivity to voltage changes, further boosting its efficiency.

Novel quantum algorithm for high-quality solutions to combinatorial optimization problems

Mon, 25 Mar 2024 15:41:24 +0000

Conventional quantum algorithms are not feasible for solving combinatorial optimization problems (COPs) with constraints in the operation time of quantum computers. To address this issue, researchers have developed a novel algorithm called post-processing variationally scheduled quantum algorithm. The novelty of this innovative algorithm lies in the use of a post-processing technique combined with variational scheduling to achieve high-quality solutions to COPs in a short time.

Open Letter to Anti-Zionists on Twitter

Scott — Mon, 25 Mar 2024 05:53:36 +0000

Dear Twitter Anti-Zionists,

For five months, ever since Oct. 7, I’ve read you obsessively. While my current job is supposed to involve protecting humanity from the dangers of AI (with a side of quantum computing theory), I’m ashamed to say that half the days I don’t do any science; instead I just scroll and scroll, reading anti-Israel content and then pro-Israel content and then more anti-Israel content. I thought refusing to post on Twitter would save me from wasting my life there as so many others have, but apparently it doesn’t, not anymore. (No, I won’t call it “X.”)

At the high end of the spectrum, I religiously check the tweets of Paul Graham, a personal hero and inspiration to me ever since he wrote Why Nerds Are Unpopular twenty years ago, and a man with whom I seem to resonate deeply on every important topic except for two: Zionism and functional programming. At the low end, I’ve read hundreds of the seemingly infinite army of Tweeters who post images of hook-nosed rats with black hats and sidecurls and dollar signs in their eyes, sneering as they strangle the earth and stab Palestinian babies. I study their detailed theories about why the October 7 pogrom never happened, and also it was secretly masterminded by Israel just to create an excuse to mass-murder Palestinians, and also it was justified and thrilling (exactly the same melange long ago embraced for the Holocaust).

I’m aware, of course, that the bottom-feeders make life too easy for me, and that a single Paul Graham who endorses the anti-Zionist cause ought to bother me more than a billion sharers of hook-nosed rat memes. And he does. That’s why, in this letter, I’ll try to stay at the higher levels of Graham’s Disagreement Hierarchy.

More to the point, though, why have I spent so much time on such a depressing, unproductive reading project?

Damned if I know. But it’s less surprising when you recall that, outside theoretical computer science, I’m (alas) mostly known to the world for having once confessed, in a discussion deep in the comment section of this blog, that I spent much of my youth obsessively studying radical feminist literature. I explained that I did that because my wish, for a decade, was to confront progressivism’s highest moral authorities on sex and relationships, and make them tell me either that

(1) I, personally, deserved to die celibate and unloved, as a gross white male semi-autistic STEM nerd and stunted emotional and aesthetic cripple, or else
(2) no, I was a decent human being who didn’t deserve that.

One way or the other, I sought a truthful answer, one that emerged organically from the reigning morality of our time and that wasn’t just an unprincipled exception to it. And I felt ready to pursue progressive journalists and activists and bloggers and humanities professors to the ends of the earth before I’d let them leave this one question hanging menacingly over everything they’d ever written, with (I thought) my only shot at happiness in life hinging on their answer to it.

You might call this my central character flaw: this need for clarity from others about the moral foundations of my own existence. I’m self-aware enough to know that it is a severe flaw, but alas, that doesn’t mean that I ever figured out how to fix it.

It’s been exactly the same way with the anti-Zionists since October 7. Every day I read them, searching for one thing and one thing only: their own answer to the “Jewish Question.” How would they ensure that the significant fraction of the world that yearns to murder all Jews doesn’t get its wish in the 21st century, as to a staggering extent it did in the 20th? I confess to caring about that question, partly (of course) because of the accident of having been born a Jew, and having an Israeli wife and family in Israel and so forth, but also because, even if I’d happened to be a Gentile, the continued survival of the world’s Jews would still seem remarkably bound up with science, Enlightenment, minority rights, liberal democracy, meritocracy, and everything else I’ve ever cared about.

I understand the charges against me. Namely: that if I don’t call for Israel to lay down its arms right now in its war against Hamas (and ideally: to dissolve itself entirely), then I’m a genocidal monster on the wrong side of history. That I value Jewish lives more than Palestinian lives. That I’m a hasbara apologist for the IDF’s mass-murder and apartheid and stealing of land. That if images of children in Gaza with their limbs blown off, or dead in their parents arms, or clawing for bread, don’t cause to admit that Israel is evil, then I’m just as evil as the Israelis are.

Unsurprisingly I contest the charges. As a father of two, I can no longer see any images of child suffering without thinking about my own kids. For all my supposed psychological abnormality, the part of me that’s horrified by such images seems to be in working order. If you want to change my mind, rather than showing me more such images, you’ll need to target the cognitive part of me: the part that asks why so many children are suffering, and what causal levers we’d need to push to reach a place where neither side’s children ever have to suffer like this ever again.

At risk of stating the obvious: my first-order model is that Hamas, with the diabolical brilliance of a Marvel villain, successfully contrived a situation where Israel could prevent the further massacring of its own population only by fighting a gruesome urban war, of a kind that always, anywhere in the world, kills tens of thousands of civilians. Hamas, of course, was helped in this plan by an ideology that considers martyrdom the highest possible calling for the innocents who it rules ruthlessly and hides underneath. But Hamas also understood that the images of civilian carnage would (rightly!) shock the consciences of Israel’s Western allies and many Israelis themselves, thereby forcing a ceasefire before the war was over, thereby giving Hamas the opportunity to regroup and, with God’s and of course Iran’s help, finally finish the job of killing all Jews another day.

And this is key: once you remember why Hamas launched this war and what its long-term goals are, every detail of Twitter’s case against Israel has to be reexamined in a new light. Take starvation, for example. Clearly the only explanation for why Israelis would let Gazan children starve is the malice in their hearts? Well, until you think through the logistical challenges of feeding 2.3 million starving people whose sole governing authority is interested only in painting the streets red with Jewish blood. Should we let that authority commandeer the flour and water for its fighters, while innocents continue to starve? No? Then how about UNRWA? Alas, we learned that UNRWA, packed with employees who cheered the Oct. 7 massacre in their Telegram channels and in some cases took part in the murders themselves, capitulates to Hamas so quickly that it effectively is Hamas. So then Israel should distribute the food itself! But as we’ve dramatically witnessed, Israel can’t distribute food without imposing order, which would seem to mean reoccupying Gaza and earning the world’s condemnation for it. Do you start to appreciate the difficulty of the problem—and why the Biden administration was pushed to absurd-sounding extremes like air-dropping food and then building a floating port?

It all seems so much easier, once you remove the constraint of not empowering Hamas in its openly-announced goal of completing the Holocaust. And hence, removing that constraint is precisely what the global left does.

For all that, by Israeli standards I’m firmly in the anti-Netanyahu, left-wing peace camp—exactly where I’ve been since the 1990s, as a teenager mourning the murder of Rabin. And I hope even the anti-Israel side might agree with me that, if all the suffering since Oct. 7 has created a tiny opening for peace, then walking through that opening depends on two things happening:

the removal of Netanyahu, and
the removal of Hamas.

The good news is that Netanyahu, the catastrophically failed “Protector of Israel,” not only can, but plausibly will (if enough government ministers show some backbone), soon be removed in a democratic election.

Hamas, by contrast, hasn’t allowed a single election since it took power in 2006, in a process notable for its opponents being thrown from the roofs of tall buildings. That’s why even my left-leaning Israeli colleagues—the ones who despise Netanyahu, who marched against him last year—support Israel’s current war. They support it because, even if the Israeli PM were Fred Rogers, how can you ever get to peace without removing Hamas, and how can you remove Hamas except by war, any more than you could cut a deal with Nazi Germany?

I want to see the IDF do more to protect Gazan civilians—despite my bitter awareness of survey data suggesting that many of those civilians would murder my children in front of me if they ever got a chance. Maybe I’d be the same way if I’d been marinated since birth in an ideology of Jew-killing, and blocked from other sources of information. I’m heartened by the fact that despite this, indeed despite the risk to their lives for speaking out, a full 15% of Gazans openly disapprove of the Oct. 7 massacre. I want a solution where that 15% becomes 95% with the passing of generations. My endgame is peaceful coexistence.

But to the anti-Zionists I say: I don’t even mind you calling me a baby-eating monster, provided you honestly field one question. Namely:

Suppose the Palestinian side got everything you wanted for it; then what would be your plan for the survival of Israel’s Jews?

Let’s assume that not only has Netanyahu lost the next election in a landslide, but is justly spending the rest of his life in Israeli prison. Waving my wand, I’ve made you Prime Minister in his stead, with an overwhelming majority in the Knesset. You now get to go down in history as the liberator of Palestine. But you’re now also in charge of protecting Israel’s 7 million Jews (and 2 million other residents) from near-immediate slaughter at the hands of those who you’ve liberated.

Granted, it seems pretty paranoid to expect such a slaughter! Or rather: it would seem paranoid, if the Palestinians’ Grand Mufti (progenitor of the Muslim Brotherhood and hence Hamas) hadn’t allied himself with Hitler in WWII, enthusiastically supported the Nazi Final Solution, and tried to export it to Palestine; if in 1947 the Palestinians hadn’t rejected the UN’s two-state solution (the one Israel agreed to) and instead launched another war to exterminate the Jews (a war they lost); if they hadn’t joined the quest to exterminate the Jews a third time in 1967; etc., or if all this hadn’t happened back before there were any settlements or occupation, when the only question on the table was Israel’s existence. It would seem paranoid if Arafat had chosen a two-state solution when Israel offered it to him at Camp David, rather than suicide bombings. It would seem paranoid if not for the candies passed out in the streets in celebration on October 7.

But if someone has a whole ideology, which they teach their children and from which they’ve never really wavered for a century, about how murdering you is a religious honor, and also they’ve actually tried to murder you at every opportunity—-what more do you want them to do, before you’ll believe them?

So, you tell me your plan for how to protect Israel’s 7 million Jews from extermination at the hands of neighbors who have their extermination—my family’s extermination—as their central political goal, and who had that as their goal long before there was any occupation of the West Bank or Gaza. Tell me how to do it while protecting Palestinian innocents. And tell me your fallback plan if your first plan turns out not to work.

We can go through the main options.

(1) UNILATERAL TWO-STATE SOLUTION

Maybe your plan is that Israel should unilaterally dismantle West Bank settlements, recognize a Palestinian state, and retreat to the 1967 borders.

This is an honorable plan. It was my preferred plan—until the horror of October 7, and then the even greater horror of the worldwide left reacting to that horror by sharing celebratory images of paragliders, and by tearing down posters of kidnapped Jewish children.

Today, you might say October 7 has sort of put a giant flaming-red exclamation point on what’s always been the central risk of unilateral withdrawal. Namely: what happens if, afterward, rather than building a peaceful state on their side of the border, the Palestinian leadership chooses instead to launch a new Iran-backed war on Israel—one that, given the West Bank’s proximity to Israel’s main population centers, makes October 7 look like a pillow fight?

If that happens, will you admit that the hated Zionists were right and you were wrong all along, that this was never about settlements but always, only about Israel’s existence? Will you then agree that Israel has a moral prerogative to invade the West Bank, to occupy and pacify it as the Allies did Germany and Japan after World War II? Can I get this in writing from you, right now? Or, following the future (October 7)² launched from a Judenfrei West Bank, will your creativity once again set to work constructing a reason to blame Israel for its own invasion—because you never actually wanted a two-state solution at all, but only Israel’s dismantlement?

(2) NEGOTIATED TWO-STATE SOLUTION

So, what about a two-state solution negotiated between the parties? Israel would uproot all West Bank settlements that prevent a Palestinian state, and resettle half a million Jews in pre-1967 Israel—in exchange for the Palestinians renouncing their goal of ending Israel’s existence, via a “right of return” or any other euphemism.

If so: congratulations, your “anti-Zionism” now seems barely distinguishable from my “Zionism”! If they made me the Prime Minister of Israel, and put you in charge of the Palestinians, I feel optimistic that you and I could reach a deal in an hour and then go out for hummus and babaganoush.

(3) SECULAR BINATIONAL STATE

In my experience, in the rare cases they deign to address the question directly, most anti-Zionists advocate a “secular, binational state” between the Jordan and Mediterranean, with equal rights for all inhabitants. Certainly, that would make sense if you believe that Israel is an apartheid state just like South Africa.

To me, though, this analogy falls apart on a single question: who’s the Palestinian Nelson Mandela? Who’s the Palestinian leader who’s ever said to the Jews, “end your Jewish state so that we can live together in peace,” rather than “end your Jewish state so that we can end your existence”? To impose a binational state would be to impose something, not only that Israelis regard as an existential horror, but that most Palestinians have never wanted either.

But, suppose we do it anyway. We place 7 million Jews, almost half the Jews who remain on Earth, into a binational state where perhaps a third of their fellow citizens hold the theological belief that all Jews should be exterminated, and that a heavenly reward follows martyrdom in blowing up Jews. The exterminationists don’t quite have a majority, but they’re the second-largest voting bloc. Do you predict that the exterminationists will give up their genocidal ambition because of new political circumstances that finally put their ambition within reach? If October-7 style pogroms against Jews turn out to be a regular occurrence in our secular binational state, how will its government respond—like the Palestinian Authority? like UNRWA? like the British Mandate? like Tsarist Russia?

In such a case, perhaps the Jews (along with those Arabs and Bedouins and Druze and others who cast their lot with the Jews) would need form a country-within-a-country: their own little autonomous zone within the binational state, with its own defense force. But of course, such a country-within-a-country already formed, for pretty much this exact reason. It’s called Israel. A cycle has been detected in your arc of progress.

(4) EVACUATION OF THE JEWS FROM ISRAEL

We come now to the anti-Zionists who are plainspoken enough to say: Israel’s creation was a grave mistake, and that mistake must now be reversed.

This is a natural option for anyone who sees Israel as an “illegitimate settler-colonial project,” like British India or French Algeria, but who isn’t quite ready to call for another Jewish genocide.

Again, the analogy runs into obvious problems: Israelis would seem to be the first “settler-colonialists” in the history of the world who not only were indigenous to the land they colonized, as much as anyone was, but who weren’t colonizing on behalf of any mother country, and who have no obvious such country to which they can return.

Some say spitefully: then let the Jews go back to Poland. These people might be unaware that, precisely because of how thorough the Holocaust was, more Israeli Jews trace their ancestry to Muslim countries than to Europe. Is there to be a “right of return” to Egypt, Iraq, Morocco, and Yemen, for all the Jews forcibly expelled from those places and for their children and grandchildren?

Others, however, talk about evacuating the Jews from Israel with goodness in their hearts. They say: we’d love the Israelis’ economic dynamism here in Austin or Sydney or Oxfordshire, joining their many coreligionists who already call these places home. What’s more, they’ll be safer here—who wants to live with missiles raining down on their neighborhood? Maybe we could even set aside some acres in Montana for a new Jewish homeland.

Again, if this is your survival plan, I’m a billion times happier to discuss it openly than to have it as unstated subtext!

Except, maybe you could say a little more about the logistics. Who will finance the move? How confident are you that the target country will accept millions of defeated, desperate Jews, as no country on earth was the last time this question arose?

I realize it’s no longer the 1930s, and Israel now has friends, most famously in America. But—what’s a good analogy here? I’ve met various Silicon Valley gazillionaires. I expect that I could raise millions from them, right now, if I got them excited about a new project in quantum computing or AI or whatever. But I doubt I could raise a penny from them if I came to them begging for their pity or their charity.

Likewise: for all the anti-Zionists’ loudness, a solid majority of Americans continue to support Israel (which, incidentally, provides a much simpler explanation than the hook-nosed perfidy of AIPAC for why Congress and the President mostly support it). But it seems to me that Americans support Israel in the “exciting project” sense, rather than in the “charity” sense. They like that Israelis are plucky underdogs who made the deserts bloom, and built a thriving tech industry, and now produce hit shows like Shtisel and Fauda, and take the fight against a common foe to the latter’s doorstep, and maintain one of the birthplaces of Western civilization for tourists and Christian pilgrims, and restarted the riveting drama of the Bible after a 2000-year hiatus, which some believe is a crucial prerequisite to the Second Coming.

What’s important, for present purposes, is not whether you agree with any of these rationales, but simply that none of them translate into a reason to accept millions of Jewish refugees.

But if you think dismantling Israel and relocating its seven million Jews is a workable plan—OK then, are you doing anything to make th

Verifying the work of quantum computers

Wed, 20 Mar 2024 20:05:31 +0000

Researchers have invented a new method by which classical computers can measure the error rates of quantum machines without having to fully simulate them.

Quantum talk with magnetic disks

Wed, 20 Mar 2024 20:04:24 +0000

Quantum computers promise to tackle some of the most challenging problems facing humanity today. While much attention has been directed towards the computation of quantum information, the transduction of information within quantum networks is equally crucial in materializing the potential of this new technology. Addressing this need, a research team is now introducing a new approach for transducing quantum information: the team has manipulated quantum bits, so called qubits, by harnessing the magnetic field of magnons -- wave-like excitations in a magnetic material -- that occur within microscopic magnetic disks.

Waterloo researcher wins 2024 Dorothy Killam Research Fellowship

Elizabeth Kleisath — Tue, 19 Mar 2024 00:00:00 +0000

Tuesday, March 19, 2024

En francais

Where quantum computers can score

Mon, 18 Mar 2024 18:24:30 +0000

The traveling salesman problem is considered a prime example of a combinatorial optimization problem. Now a team has shown that a certain class of such problems can actually be solved better and much faster with quantum computers than with conventional methods.

Unlocking the quantum future

Rachel Yang | Research Laboratory of Electronics — Mon, 18 Mar 2024 13:55:00 +0000

Quantum computing is the next frontier for faster and more powerful computing technologies. It has the potential to better optimize routes for shipping and delivery, speed up battery development for electric vehicles, and more accurately predict trends in financial markets. But to unlock the quantum future, scientists and engineers need to solve outstanding technical challenges while continuing to explore new applications.

One place where they’re working towards this future is the MIT Interdisciplinary Quantum Hackathon, or iQuHACK for short (pronounced “i-quack,” like a duck). Each year, a community of quhackers (quantum hackers) gathers at iQuHACK to work on quantum computing projects using real quantum computers and simulators. This year, the hackathon was held both in-person at MIT and online over three days in February.

Quhackers worked in teams to advance the capability of quantum computers and to investigate promising applications. Collectively, they tackled a wide range of projects, such as running a quantum-powered dating service, building an organ donor matching app, and breaking into quantum vaults. While working, quhackers could consult with scientists and engineers in attendance from sponsoring companies. Many sponsors also received feedback and ideas from quhackers to help improve their quantum platforms.

But organizing iQuHACK 2024 was no easy feat. Co-chairs Alessandro Buzzi and Daniela Zaidenberg led a committee of nine members to hold the largest iQuHACK yet. “It wouldn’t have been possible without them,” Buzzi said. The hackathon hosted 260 in-person quhackers and 1,000 remote quhackers, representing 77 countries in total. More than 20 scientists and engineers from sponsoring companies also attended in person as mentors for quhackers.

Each team of quhackers tackled one of 10 challenges posed by the hackathon’s eight major sponsoring companies. Some challenges asked quhackers to improve computing performance, such as by making quantum algorithms faster and more accurate. Other challenges asked quhackers to explore applying quantum computing to other fields, such as finance and machine learning. The sponsors worked with the iQuHACK committee to craft creative challenges with industry relevance and societal impact. “We wanted people to be able to address an interesting challenge [that has] applications in the real world,” says Zaidenberg.

One team of quhackers looked for potential quantum applications and found one close to home: dating. A team member, Liam Kronman, had previously built dating apps but disliked that matching algorithms for normal classical computers “require [an overly] strict setup.” With these classical algorithms, people must be split into two groups — for example, men and women — and matches can only be made between these groups. But with quantum computers, matching algorithms are more flexible and can consider all possible combinations, enabling the inclusion of multiple genders and gender preferences.

Kronman and his team members leveraged these quantum algorithms to build a quantum-powered dating platform called MITqute (pronounced “meet cute”). To date, the platform has matched at least 240 people from the iQuHACK and MIT undergrad communities. In a follow-up survey, 13 out of 41 respondents reported having talked with their match, with at least two pairs setting up dates. “I really lucked out with this one,” one respondent wrote.

Another team of quhackers also based their project on quantum matching algorithms but instead leveraged the algorithms’ power for medical care. The team built a mobile app that matches organ donors to patients, earning them the hackathon’s top social impact award.

But they almost didn’t go through with their project. “At one point, we were considering scrapping the whole thing because we thought we couldn’t implement the algorithm,” says Alma Alex, one of the developers. After talking with their hackathon mentor for advice, though, the team learned that another group was working on a similar type of project — incidentally, the MITqute team. Knowing that others were tackling the same problem inspired them to persevere.

A sense of community also helped to motivate other quhackers. For one of the challenges, quhackers were tasked with hacking into 13 virtual quantum vaults. Teams could see each other’s progress on each vault in real time on a leaderboard, and this knowledge informed their strategies. When the first vault was successfully hacked by a team, progress from many other teams spiked on that vault and slowed down on others, says Daiwei Zhu, a quantum applications scientist at IonQ and one of the challenge’s two architects.

The vault challenge may appear to be just a fun series of puzzles, but the solutions can be used in quantum computers to improve their efficiency and accuracy. To hack into a vault, quhackers had to first figure out its secret key — an unknown quantum state — using a maximum of 20 probing tests. Then, they had to change the key’s state to a target state. These types of characterizations and modifications of quantum states are “fundamental” for quantum computers to work, says Jason Iaconis, a quantum applications engineer at IonQ and the challenge’s other architect.

But the best way to characterize and modify states is not yet clear. “Some of the [vaults] we [didn’t] even know how to solve ourselves,” Zhu says. At the end of the hackathon, six vaults had at least one team mostly hack into them. (In the quantum world where gray areas exist, it’s possible to partly hack into a vault.)

The community of scientists and engineers formed at iQuHACK persists beyond the weekend, and many members continue to grow the community outside the hackathon. Inspired quhackers have gone on to start their own quantum computing clubs at their universities. A few years ago, a group of undergraduate quhackers from different universities formed a Quantum Coalition that now hosts their own quantum hackathons. “It’s crazy to see how the hackathon itself spreads and how many people start their own initiatives,” co-chair Zaidenberg says.

The three-day hackathon opened with a keynote from MIT Professor Will Oliver, which included an overview of basic quantum computing concepts, current challenges, and computing technologies. Following that were industry talks and a panel of six industry and academic quantum experts, including MIT Professor Peter Shor, who is known for developing one of the most famous quantum algorithms. The panelists discussed current challenges, future applications, the importance of collaboration, and the need for ample testing.

Later, sponsors held technical workshops where quhackers could learn the nitty-gritty details of programming on specific quantum platforms. Day one closed out with a talk by research scientist Xinghui Yin on the role of quantum technology at LIGO, the Laser Interferometer Gravitational-Wave Observatory that first detected gravitational waves. The next day, the hackathon’s challenges were announced at 10 a.m., and hacking kicked off at the MIT InnovationHQ. In the afternoon, attendees could also tour MIT quantum computing labs.

Hacking continued overnight at the MIT Museum and ended back at MIT iHQ at 10 a.m. on the final day. Quhackers then presented their projects to panels of judges. Afterward, industry speakers gave lightning talks about each of their company’s latest quantum technologies and future directions. The hackathon ended with a closing ceremony, where sponsors announced the awards for each of the 10 challenges.

The hackathon was captured in a three-part video by Albert Figurt, a resident artist at MIT. Figurt shot and edited the footage in parallel with the hackathon. Each part represented one day of the hackathon and was released on the subsequent day.

Throughout the weekend, quhackers and sponsors consistently praised the hackathon’s execution and atmosphere. “That was amazing … never felt so much better, one of the best hackathons I did from over 30 hackathons I attended,” Abdullah Kazi, a quhacker, wrote on the iQuHACK Slack.

Ultimately, “[we wanted to] help people to meet each other,” co-chair Buzzi says. “The impact [of iQuHACK] is scientific in some way, but it’s very human at the most important level.”

NSERC Alliance grants 2024 recognize five quantum projects at the University of Waterloo

Elizabeth Kleisath — Mon, 18 Mar 2024 00:00:00 +0000

Monday, March 18, 2024

En francais

Never go to “Planet Word” in Washington DC

Scott — Fri, 15 Mar 2024 20:49:37 +0000

In fact, don’t try to take kids to Washington DC if you can possibly avoid it.

This is my public service announcement. This is the value I feel I can add to the world today.

Dana and I decided to take the kids to DC for spring break. The trip, alas, has been hell—a constant struggle against logistical failures. The first days were mostly spent sitting in traffic or searching for phantom parking spaces that didn’t exist. (So then we switched to the Metro, and promptly got lost, and had our metro cards rejected by the machines.) Or, at crowded cafes, I spent the time searching for a table so my starving kids could eat—and then when I finally found a table, a woman, smug and sure-faced, evicted us from the table because she was “going to” sit there, and my kids had to see that their dad could not provide for their basic needs, and that woman will never face any consequence for what she did.

Anyway, this afternoon, utterly frazzled and stressed and defeated, we entered “Planet Word,” a museum about language. Sounds pretty good, right? Except my soon-to-be 7-year-old son got bored by numerous exhibits that weren’t for him. So I told him he could lead the way and find any exhibit he liked.

Finally my son found an exhibit that fascinated him, one where he could weigh plastic fruits on a balancing scale. He was engrossed by it, he was learning, he was asking questions, I reflected that maybe the trip wasn’t a total loss … and that’s when a museum employee pointed at us, and screamed at us to leave the room, because “this exhibit was sold out.”

The room was actually almost empty (!). No one had stopped us from entering the room. No one else was waiting to use the balancing scale. There was no sign to warn us we were doing anything wrong. I would’ve paid them hundreds of dollars in that moment if only we could stay. My son didn’t understand why he was suddenly treated as a delinquent. He then wanted to leave the whole museum, and so did I. The day was ruined for us.

Mustering my courage to do something uncharacteristic for me, I complained at the front desk. They sneered and snickered at me, basically told me to go to hell. Looking deeply into their dumb, blank expressions, I realized that I had as much chance of any comprehension or sympathy as I’d have from a warthog. It’s true that, on the scale of all the injustices in the history of the world, this one surely didn’t crack the top quadrillion. But for me, in that moment, it came to stand for all the others. Which has always been my main weakness as a person, that injustice affects me in that way.

Speaking of which, there was one part of DC trip that went exactly like it was supposed to. That was our visit to the United States Holocaust Memorial Museum. Why? Because I feel like that museum, unlike all the rest, tells me the truth about the nature of the world that I was born into—and seeing the truth is perversely comforting. I was born into a world that right now, every day, is filled with protesters screaming for my death, for my family’s death—and this is accepted as normal, and those protesters sleep soundly at night, congratulating themselves for their progressivism and enlightenment. And thinking about those protesters, and their predecessors 80 years ago who perpetrated the Holocaust or who stood by and let it happen, is the only thing that really puts blankfaced museum employees into perspective for me. Like, of course a world with the former is also going to have the latter—and I should count myself immeasurably lucky if the latter is all I have to deal with, if the empty-skulled and the soul-dead can only ruin my vacation and lack the power to murder my family.

And to anyone who reached the end of this post and who feels like it was an unwelcome imposition on their time: I’m sorry. But the truth is, posts like this are why I started this blog and why I continue it. If I’ve ever imparted any interesting information or ideas, that’s a byproduct that I’m thrilled about. But I’m cursed to be someone who wakes up every morning, walks around every day, and goes to sleep every night crushed by the weight of the world’s injustice, and outside of technical subjects, the only thing that’s ever motivated me to write is that words are the only justice available to me.

Quantum Community

Elizabeth Kleisath — Thu, 14 Mar 2024 00:00:00 +0000

Thursday, March 14, 2024

With a focus on collaboration and community, the Institute for Quantum Computing (IQC) is proud to host regular social events for our members. While media and popular culture often portray the image of a lone researcher working late nights in a lab or at a computer to make breakthroughs, the more realistic portrayal of new ideas and discoveries can be encompassed through partnerships and teamwork.

Staying in the loop: How superconductors are helping computers 'remember'

Wed, 13 Mar 2024 17:54:47 +0000

To advance neuromorphic computing, some researchers are looking at analog improvements -- advancing not just software, but hardware too. Research shows a promising new way to store and transmit information using disordered superconducting loops.

Satellites for quantum communications

Wed, 13 Mar 2024 17:54:42 +0000

Through steady advances in the development of quantum computers and their ever-improving performance, it will be possible in the future to crack our current encryption processes. To address this challenge, researchers are developing encryption methods that will apply physical laws to prevent the interception of messages. To safeguard communications over long distances, the QUICK space mission will deploy satellites.

Powerful new tool ushers in new era of quantum materials research

Tue, 12 Mar 2024 17:37:16 +0000

Research in quantum materials is paving the way for groundbreaking discoveries and is poised to drive technological advancements that will redefine the landscapes of industries like mining, energy, transportation, and medtech. A technique called time- and angle-resolved photoemission spectroscopy (TR-ARPES) has emerged as a powerful tool, allowing researchers to explore the equilibrium and dynamical properties of quantum materials via light-matter interaction.

Design rules and synthesis of quantum memory candidates

Mon, 11 Mar 2024 18:59:50 +0000

In the quest to develop quantum computers and networks, there are many components that are fundamentally different than those used today. Like a modern computer, each of these components has different constraints. However, it is currently unclear what materials can be used to construct those components for the transmission and storage of quantum information.

Quantum Quest Seed Fund announces twelfth round of funding

Elizabeth Kleisath — Thu, 07 Mar 2024 00:00:00 +0000

Thursday, March 7, 2024

En francais

Since 2017, the Quantum Quest Seed Fund (QQSF) has awarded more than $2.88 million to quantum researchers across the University of Waterloo. This winter’s round of funding has been awarded to three Waterloo professors, as they explore and innovate new ideas and applications for quantum devices.

Making quantum bits fly

Wed, 06 Mar 2024 20:06:47 +0000

Physicists are developing a method that could enable the stable exchange of information in quantum computers. In the leading role: photons that make quantum bits 'fly'.

On being faceless

Scott — Wed, 06 Mar 2024 14:29:13 +0000

Update: Alright, I’m back in. (After trying the same recovery mechanisms that didn’t work before, but suddenly did work this afternoon.) Thanks also to the Facebook employee who emailed offering to help. Now I just need to decide the harder question of whether I want to be back in!

So I’ve been locked out of Facebook and Messenger, possibly forever. It started yesterday morning, when Facebook went down for the entire world. Now it’s back up for most people, but I can’t get in—neither with passwords (none of which work), nor with text messages to my phone (my phone doesn’t receive them for some reason). As a last-ditch measure, I submitted my driver’s license into a Facebook black hole from which I don’t expect to hear back.

Incidentally, this sort of thing is why, 25 years ago, I became a theoretical rather than applied computer scientist. Even before you get to any serious software engineering, the applied part of computing involves a neverending struggle to make machines do what you need them to do—get a document to print, a website to load, a software package to install—in ways that are harrowing and not the slightest bit intellectually interesting. You learn, not about the nature of reality, but only about the terrible design decisions of other people. I might as well be a 90-year-old grandpa with such things, and if I didn’t have the excuse of being a theorist, that fact would constantly humiliate me before my colleagues.

Anyway, maybe some Facebook employee will see this post and decide to let me back in. Otherwise, it feels like a large part of my life has been cut away forever—but maybe that’s good, like cutting away a malignant tumor. Maybe, even if I am let back in, I should refrain from returning, or at least severely limit the time I spend there.

The truth is that, over the past eight years or so, I let more and more of my online activity shift from this blog to Facebook. Partly that’s because (as many others have lamented) the Golden Age of Blogs came to an end, with intellectual exploration and good-faith debate replaced by trolling, sniping, impersonation, and constant attempts to dox opponents and ruin their lives. As a result, more and more ideas for new blog posts stayed in my drafts folder—they always needed just one more revision to fortify them against inevitable attack, and then that one more revision never happened. It was simply more comfortable to post my ideas on Facebook, where the feedback came from friends and colleagues using their real names, and where any mistakes I made would be contained. But, on the reflection that comes from being locked out, maybe Facebook was simply a trap. What I have neither the intellectual courage to say in public, nor the occasion to say over dinner with real-life friends and family and colleagues, maybe I should teach myself not to say at all.

Shortcut to Success: Toward fast and robust quantum control through accelerating adiabatic passage

Tue, 05 Mar 2024 18:43:15 +0000

Researchers achieved the acceleration of adiabatic evolution of a single spin qubit in gate-defined quantum dots. After the pulse optimization to suppress quasistatic noises, the spin flip fidelity can be as high as 97.5% in GaAs quantum dots. This work may be useful to achieve fast and high-fidelity quantum computing.

Network of quantum sensors boosts precision

Mon, 04 Mar 2024 18:58:23 +0000

Quantum sensor technology promises even more precise measurements of physical quantities. A team has now compared the signals of up to 91 quantum sensors with each other and thus successfully eliminated the noise caused by interactions with the environment. Correlation spectroscopy can be used to increase the precision of sensor networks.

AI-enabled atomic robotic probe to advance quantum material manufacturing

Fri, 01 Mar 2024 18:47:03 +0000

Scientists have pioneered a new methodology of fabricating carbon-based quantum materials at the atomic scale by integrating scanning probe microscopy techniques and deep neural networks. This breakthrough highlights the potential of implementing artificial intelligence at the sub-angstrom scale for enhanced control over atomic manufacturing, benefiting both fundamental research and future applications.

Scientists make nanoparticles dance to unravel quantum limits

Fri, 01 Mar 2024 18:46:51 +0000

The question of where the boundary between classical and quantum physics lies is one of the longest-standing pursuits of modern scientific research and in new research, scientists demonstrate a novel platform that could help us find an answer.

Umbrella for atoms: The first protective layer for 2D quantum materials

Fri, 01 Mar 2024 18:46:31 +0000

As silicon-based computer chips approach their physical limitations in the quest for faster and smaller designs, the search for alternative materials that remain functional at atomic scales is one of science's biggest challenges. In a groundbreaking development, researchers have engineered a protective film that shields quantum semiconductor layers just one atom thick from environmental influences without compromising their revolutionary quantum properties. This puts the application of these delicate atomic layers in ultrathin electronic components within realistic reach.

Quantum LiDAR

Elizabeth Kleisath — Thu, 29 Feb 2024 00:00:00 +0000

Thursday, February 29, 2024

En francais

What do you do when your lab space is too small to test the distance requirements for a new long-range sensor and detector in development? Alex Maierean and Luke Neal, graduate students at the Institute for Quantum Computing (IQC) recently navigated this challenge for their latest project.

Resurrecting niobium for quantum science

Tue, 27 Feb 2024 01:46:36 +0000

Niobium has long been considered an underperformer in superconducting qubits. Scientists have now engineered a high-quality niobium-based qubit, taking advantage of niobium's superior qualities.

Scientists closer to solving mysteries of universe after measuring gravity in quantum world

Mon, 26 Feb 2024 02:25:12 +0000

Scientists are closer to unravelling the mysterious forces of the universe after working out how to measure gravity on a microscopic level. Experts have never fully understood how the force works in the tiny quantum world -- but now physicists have successfully detected a weak gravitational pull on a tiny particle using a new technique.

Measuring the properties of light: Scientists realize new method for determining quantum states

Mon, 26 Feb 2024 02:25:03 +0000

Scientists have used a new method to determine the characteristics of optical, i.e. light-based, quantum states. For the first time, they are using certain photon detectors -- devices that can detect individual light particles -- for so-called homodyne detection. The ability to characterize optical quantum states makes the method an essential tool for quantum information processing.

Major funding for quantum tech companies spun out of Waterloo to advance and commercialize quantum technology

Elizabeth Kleisath — Mon, 26 Feb 2024 00:00:00 +0000

Monday, February 26, 2024

En francais

Federal funding will accelerate quantum startups’ products and solutions for domestic and global markets.

Electrons become fractions of themselves in graphene

Wed, 21 Feb 2024 21:03:43 +0000

Physicists have observed fractional quantum Hall effect in simple pentalayer graphene. The finding could make it easier to develop more robust quantum computers.

Electrons become fractions of themselves in graphene, study finds

Jennifer Chu | MIT News — Wed, 21 Feb 2024 16:00:00 +0000

The electron is the basic unit of electricity, as it carries a single negative charge. This is what we’re taught in high school physics, and it is overwhelmingly the case in most materials in nature.

But in very special states of matter, electrons can splinter into fractions of their whole. This phenomenon, known as “fractional charge,” is exceedingly rare, and if it can be corralled and controlled, the exotic electronic state could help to build resilient, fault-tolerant quantum computers.

To date, this effect, known to physicists as the “fractional quantum Hall effect,” has been observed a handful of times, and mostly under very high, carefully maintained magnetic fields. Only recently have scientists seen the effect in a material that did not require such powerful magnetic manipulation.

Now, MIT physicists have observed the elusive fractional charge effect, this time in a simpler material: five layers of graphene — an atom-thin layer of carbon that stems from graphite and common pencil lead. They report their results today in Nature.

They found that when five sheets of graphene are stacked like steps on a staircase, the resulting structure inherently provides just the right conditions for electrons to pass through as fractions of their total charge, with no need for any external magnetic field.

The results are the first evidence of the “fractional quantum anomalous Hall effect” (the term “anomalous” refers to the absence of a magnetic field) in crystalline graphene, a material that physicists did not expect to exhibit this effect.

“This five-layer graphene is a material system where many good surprises happen,” says study author Long Ju, assistant professor of physics at MIT. “Fractional charge is just so exotic, and now we can realize this effect with a much simpler system and without a magnetic field. That in itself is important for fundamental physics. And it could enable the possibility for a type of quantum computing that is more robust against perturbation.”

Ju’s MIT co-authors are lead author Zhengguang Lu, Tonghang Han, Yuxuan Yao, Aidan Reddy, Jixiang Yang, Junseok Seo, and Liang Fu, along with Kenji Watanabe and Takashi Taniguchi at the National Institute for Materials Science in Japan.

A bizarre state

The fractional quantum Hall effect is an example of the weird phenomena that can arise when particles shift from behaving as individual units to acting together as a whole. This collective “correlated” behavior emerges in special states, for instance when electrons are slowed from their normally frenetic pace to a crawl that enables the particles to sense each other and interact. These interactions can produce rare electronic states, such as the seemingly unorthodox splitting of an electron’s charge.

In 1982, scientists discovered the fractional quantum Hall effect in heterostructures of gallium arsenide, where a gas of electrons confined in a two-dimensional plane is placed under high magnetic fields. The discovery later won the group a Nobel Prize in Physics.

“[The discovery] was a very big deal, because these unit charges interacting in a way to give something like fractional charge was very, very bizarre,” Ju says. “At the time, there were no theory predictions, and the experiments surprised everyone.”

Those researchers achieved their groundbreaking results using magnetic fields to slow down the material’s electrons enough for them to interact. The fields they worked with were about 10 times stronger than what typically powers an MRI machine.

In August 2023, scientists at the University of Washington reported the first evidence of fractional charge without a magnetic field. They observed this “anomalous” version of the effect, in a twisted semiconductor called molybdenum ditelluride. The group prepared the material in a specific configuration, which theorists predicted would give the material an inherent magnetic field, enough to encourage electrons to fractionalize without any external magnetic control.

The “no magnets” result opened a promising route to topological quantum computing — a more secure form of quantum computing, in which the added ingredient of topology (a property that remains unchanged in the face of weak deformation or disturbance) gives a qubit added protection when carrying out a computation. This computation scheme is based on a combination of fractional quantum Hall effect and a superconductor. It used to be almost impossible to realize: One needs a strong magnetic field to get fractional charge, while the same magnetic field will usually kill the superconductor. In this case the fractional charges would serve as a qubit (the basic unit of a quantum computer).

Making steps

That same month, Ju and his team happened to also observe signs of anomalous fractional charge in graphene — a material for which there had been no predictions for exhibiting such an effect.

Ju’s group has been exploring electronic behavior in graphene, which by itself has exhibited exceptional properties. Most recently, Ju’s group has looked into pentalayer graphene — a structure of five graphene sheets, each stacked slightly off from the other, like steps on a staircase. Such pentalayer graphene structure is embedded in graphite and can be obtained by exfoliation using Scotch tape. When placed in a refrigerator at ultracold temperatures, the structure’s electrons slow to a crawl and interact in ways they normally wouldn’t when whizzing around at higher temperatures.

In their new work, the researchers did some calculations and found that electrons might interact with each other even more strongly if the pentalayer structure were aligned with hexagonal boron nitride (hBN) — a material that has a similar atomic structure to that of graphene, but with slightly different dimensions. In combination, the two materials should produce a moiré superlattice — an intricate, scaffold-like atomic structure that could slow electrons down in ways that mimic a magnetic field.

“We did these calculations, then thought, let’s go for it,” says Ju, who happened to install a new dilution refrigerator in his MIT lab last summer, which the team planned to use to cool materials down to ultralow temperatures, to study exotic electronic behavior.

The researchers fabricated two samples of the hybrid graphene structure by first exfoliating graphene layers from a block of graphite, then using optical tools to identify five-layered flakes in the steplike configuration. They then stamped the graphene flake onto an hBN flake and placed a second hBN flake over the graphene structure. Finally, they attached electrodes to the structure and placed it in the refrigerator, set to near absolute zero.

As they applied a current to the material and measured the voltage output, they started to see signatures of fractional charge, where the voltage equals the current multiplied by a fractional number and some fundamental physics constants.

“The day we saw it, we didn’t recognize it at first,” says first author Lu. “Then we started to shout as we realized, this was really big. It was a completely surprising moment.”

“This was probably the first serious samples we put in the new fridge,” adds co-first author Han. “Once we calmed down, we looked in detail to make sure that what we were seeing was real.”

With further analysis, the team confirmed that the graphene structure indeed exhibited the fractional quantum anomalous Hall effect. It is the first time the effect has been seen in graphene.

“Graphene can also be a superconductor,” Ju says. “So, you could have two totally different effects in the same material, right next to each other. If you use graphene to talk to graphene, it avoids a lot of unwanted effects when bridging graphene with other materials.”

For now, the group is continuing to explore multilayer graphene for other rare electronic states.

“We are diving in to explore many fundamental physics ideas and applications,” he says. “We know there will be more to come.”

This research is supported in part by the Sloan Foundation, and the National Science Foundation.

Engineers achieve breakthrough in quantum sensing

Tue, 20 Feb 2024 19:46:16 +0000

A collaborative project has made a breakthrough in enhancing the speed and resolution of wide-field quantum sensing, leading to new opportunities in scientific research and practical applications.