2025-09-12 14:46:11
I’m thrilled that our paper entitled Demonstrating an unconditional separation between quantum and classical information resources, based on a collaboration between UT Austin and Quantinuum, is finally up on the arXiv. I’m equally thrilled that my coauthor and former PhD student William Kretschmer — who led the theory for this project, and even wrote much of the code — is now my faculty colleague at UT Austin! My physics colleague Nick Hunter-Jones and my current PhD student Sabee Grewal made important contributions as well. I’d especially like to thank the team at Quantinuum for recognizing a unique opportunity to test and showcase their cutting-edge hardware, and collaborating with us wild-eyed theorists to make it happen. This is something that, crucially, would not have been feasible with the quantum computing hardware of only a couple years ago.
Here’s our abstract, which I think explains what we did clearly enough, although do read the paper for more:
A longstanding goal in quantum information science is to demonstrate quantum computations that cannot be feasibly reproduced on a classical computer. Such demonstrations mark major milestones: they showcase fine control over quantum systems and are prerequisites for useful quantum computation. To date, quantum advantage has been demonstrated, for example, through violations of Bell inequalities and sampling-based quantum supremacy experiments. However, both forms of advantage come with important caveats: Bell tests are not computationally difficult tasks, and the classical hardness of sampling experiments relies on unproven complexity-theoretic assumptions. Here we demonstrate an unconditional quantum advantage in information resources required for a computational task, realized on Quantinuum’s H1-1 trapped-ion quantum computer operating at a median two-qubit partial-entangler fidelity of 99.941(7)%. We construct a task for which the most space-efficient classical algorithm provably requires between 62 and 382 bits of memory, and solve it using only 12 qubits. Our result provides the most direct evidence yet that currently existing quantum processors can generate and manipulate entangled states of sufficient complexity to access the exponentiality of Hilbert space. This form of quantum advantage — which we call quantum information supremacy — represents a new benchmark in quantum computing, one that does not rely on unproven conjectures.
I’m very happy to field questions about this paper in the comments section.
Unrelated Announcement: As some of you might have seen, yesterday’s Wall Street Journal carried a piece by Dan Kagan-Kans on “The Rise of ‘Conspiracy Physics.'” I talked to the author for the piece, and he quoted this blog in the following passage:
This resentment of scientific authority figures is the major attraction of what might be called “conspiracy physics.” Most fringe theories are too arcane for listeners to understand, but anyone can grasp the idea that academic physics is just one more corrupt and self-serving establishment. The German physicist Sabine Hossenfelder has attracted 1.72 million YouTube subscribers in part by attacking her colleagues: “Your problem is that you’re lying to the people who pay you,” she declared. “Your problem is that you’re cowards without a shred of scientific integrity.”
In this corner of the internet, the scientist Scott Aaronson has written, “Anyone perceived as the ‘mainstream establishment’ faces a near-insurmountable burden of proof, while anyone perceived as ‘renegade’ wins by default if they identify any hole whatsoever in mainstream understanding.”
2025-09-05 04:39:39
In response to my recent blog posts, which expressed views that are entirely boring and middle-of-the-road for Americans as a whole, American Jews, and Israelis (“yes, war to destroy Hamas is basically morally justified, even if there are innocent casualties, as the only possible way to a future of coexistence and peace”)—many people declared that I was a raving genocidal maniac who wants to see all Palestinian children murdered out of sheer hatred, and who had destroyed his career and should never show his face in public again.
Others, however, called me something even worse than a genocidal maniac. They called me a Republican!
So I’d like to state for the record:
(1) In my opinion, Trump II remains by far the worst president in American history—beating out the second-worst, either Trump I or Andrew Jackson. Trump is destroying vaccines and science and universities and renewable energy and sane AI policy and international trade and cheap, lifesaving foreign aid and the rule of law and everything else that’s good, and he’s destroying them because they’re good—because even if destroying them hurts his own voters and America’s standing in the world, it might hurt the educated elites even more. It’s almost superfluous to mention that, while Trump himself is neither of these things, the MAGA movement that will anoint his successor now teems with antisemites and Holocaust “revisionists.”
(2) Thus, I’ll continue to vote straight-ticket Democrat, and donate money to Democrats, so long as the Democrats in question are seriously competing for Zionist Jewish votes at all—as, for example, has every Democratic presidential candidate in my lifetime so far.
(3) If it came down to an Israel-hating Squad Democrat versus a MAGA Republican, I’m not sure what I’d do, but I’d plausibly sit out the election or lodge a protest vote.
(4) In the extremely unlikely event that I had to choose between an Israel-hating Squad Democrat and some principled anti-MAGA Republican like Romney or Liz Cheney—then and only then do I expect that I’d vote Republican, for the first time in my life, a new and unfamiliar experience.
2025-09-03 06:00:36
In my last post, I wrote about all the hate mail I’ve received these past few days. I even shared a Der-Stürmer-like image of a bloodthirsty, hook-nosed Orthodox Jew that some troll emailed me, after he’d repeatedly promised to send me a “diagram” that would improve my understanding of the Middle East. (Incredibly, commenters on Peter Woit’s blog then blamed me for this antisemitic image, mistakenly imagining that I’d created it myself, and then used their false assumption as further proof of my mental illness.)
Thanks to everyone who wrote to ask whether I’m holding up OK. The answer is: better than you’d expect! The first time you get attacked by dozens of Internet randos, it does feel like your life is over. But the sixth or seventh time? After you’ve experienced, firsthand, how illusory these people’s power over you actually is—how they can’t even dent your scientific career, can’t separate you from any of the friends who matter most to you (let alone your family), can’t really do anything to you beyond whatever they induce you to do to yourself? Then the deadly wolves appear more like poodles yapping from behind a fence. Try it and see!
Today I want to focus on a different kind of message that’s been filling my inbox. Namely, people telling me to stay strong, to keep up my courage, that everything I wrote strikes them as just commonsense morality.
It won’t surprise anyone that many of these people are Jews. But almost as many are not. I was touched to hear from several of my non-Jewish scientific colleagues—ones I’d had no idea were in my corner—that they are in my corner.
Then there was the American Gentile who emailed me a story about how, seeing an Orthodox family after October 7, he felt an urge to run up and tell them that, if worst ever came to worst, they could hide in his basement (“and I own guns,” he added). Amusingly, he added that his wife successfully dissuaded him from actually making such an offer, pointing out that it might freak out the recipients.
I replied that, here in America, I don’t expect that I’ll ever need to hide in anyone’s basement. But, I added, the only reason I don’t expect it is that there are so many Americans who, regardless of any religious or ideological differences, would hide their Jewish neighbors in their basements if necessary.
I also—despite neither I nor this guy exactly believing in God—decided to write a blessing for him, which came out as follows:
May your seed multiply a thousandfold, for like King Cyrus of Persia, you are a righteous man among the Gentiles. But also, if you’re ever in Austin, be sure to hit me up for tacos and beer.
I’m even grateful, in a way, to SneerClub, and to Woit and his minions. I’m grateful to them for so dramatically confirming that I’m not delusional: some portion of the world really is out to get me. I probably overestimated their power, but not their malevolence.
I’ve learned, for example, that there are no words, however balanced or qualified, with which I can express the concept that Israel needs to defeat Hamas for the sake of both Israeli and Palestinian children, which won’t lead to Woit calling me a “genocide apologist who wants to see all the children in Gaza killed.” Nor are there any words with which to express my solidarity with the Jewish Columbia students who, according to an official university investigation, were last year systematically excluded from campus social life, intimidated, and even assaulted, and which won’t earn me names from Woit like “a fanatic allied with America’s fascist dictator.” Even my months-long silence about these topics got me labeled as “complicit with fascism and genocide.”
Realizing this is oddly liberating. When your back is to the wall in that way, either you can surrender, or else you can defend yourself. Your enemy has already done you the “favor” of eliminating any third options. Which, again, is just Zionism in a nutshell. It’s the lesson not only of 3,000 years of Jewish history, but also of superhero comics and of much of the world’s literature and cinema. It takes a huge amount of ideological indoctrination before such things stop being obvious.
Reading the SneerClubbers’ armchair diagnoses of my severe mental illness, paranoia, persecution complex, grandiosity, etc. etc. I had the following thought, paraphrasing Shaw:
Yes, they’re absolutely right that psychologically well-adjusted people generally do figure out how to adapt themselves to the reigning morality of their social environment—as indicated by the Asch conformity test, the Milgram electric-shock experiment, and the other classics of social psychology.
It takes someone psychologically troubled, in one way or another, to persist in trying to adapt the reigning morality of their social environment to themselves.
If so, however, this suggests that all the moral progress of humanity depends on psychologically troubled people—a realization for which I’m deeply grateful.
2025-09-01 04:25:05
Hardly for the first time in my life, this weekend I got floridly denounced every five minutes—on SneerClub, on the blog of Peter Woit, and in my own inbox. The charge this time was that I’m a genocidal Zionist who wants to kill all Palestinian children purely because of his mental illness and raging persecution complex.
Yes, that’s right, I’m the genocidal one—me, whose lifelong dream is that, just like Germany and Japan rose from their necessary devastation in WWII to become pillars of our global civilization, so too the children in Gaza, the West Bank, Syria, Lebanon, and Iran will one day grow up in free and prosperous societies at peace with the West and with Israel. Meanwhile, those who demand an actual genocide of the Jews, another one—those who pray to Allah for it, who attempt it over and over, who preach it to schoolchildren, who celebrate their progress toward it in the streets—they’re all as innocent as lambs.
Yesterday, in The Free Press, came the report of a British writer who traveled to southern Lebanon, and met an otherwise ordinary young man there … who turned out to be excited for Muslims and Christians to join forces to slaughter all the Yahood, and who fully expected that writer would share his admiration for Hitler, the greatest Yahood-killer ever.
This is what the global far left has now allied itself with. This is what I’m right now being condemned for standing against, with commenter after commenter urging me to seek therapy.
To me, this raises a broader question: how exactly do you keep your sanity, when you live on a planet filled with brain-eaten zombies?
I’m still struggling with that question, but the best I’ve come up with is what I think of as the Weinberg Principle, after my much-missed friend and colleague here at UT Austin. Namely, I believe that it’s better to have one Steven Weinberg on your side while the rest of humanity is against you, than the opposite. Many other individuals (including much less famous ones) would also work here in place of Steve, but I’ll go with him because I think most of my readers would agree to three statements:
Maybe it’s possible to wake the zombies up. Yoram Arnon, for example, wrote the following eloquent answer on Quora, in response to the question “Why are so many against freeing Palestine?”:
When Westerners think about freedom they think about freedom of speech, freedom of expression, freedom of movement, freedom of religion, freedom to form political parties, etc.
When Palestinians say “Free Palestine” they mean freedom from Jews, and from Israel’s existence. They’re advocating for the abolition of Israel, replacing it with an Arab country.
Israel is the only country in the Middle East that is free, in the Western sense of the word. If Israel were to disappear, Palestinians would fall under an autocratic regime, just like every other Arab country, with none of the above freedoms. And, of course, Israelis would suffer a terrible fate at their hands.
Pro Palestinians are either unable to see this, or want exactly that, but thankfully many in the West do see this – the same “many” that are against “freeing Palestine”.
Palestinians need to accept Israel’s right to exist, and choose to coexist peacefully alongside it, for them to have the peace and freedom the West wants for them.
Maybe reading words like these—or the words of Coleman Hughes, or Douglas Murray, or Hussein Aboubakr Mansour, or Yassine Meskhout, or John Aziz, or Haviv Rettig Gur, or Sam Harris, or the quantum computing pioneer David Deutsch—can boot a few of the zombies’ brains back up. But even then, I fear that these reboots will be isolated successes. For every one who comes back online, a thousand will still shamble along in lockstep, chanting “brainsssssss! genocide! intifada!”
I’m acutely aware of how sheer numbers can create the illusion of argumentative strength. I know many people who were sympathetic to Israel immediately after October 7, but then gradually read the room, saw which side their bread was buttered on, etc. etc. and became increasingly hostile. My reaction, of course, has been exactly the opposite. The bigger the zombie army I see marching against me, the less inclined I feel to become a zombie myself—and the clearer to me becomes the original case for the Zionist project.
So to the pro-Zionist students—Jewish of course, but also Christian, Muslim, Hindu, atheist, and everyone else—who feel isolated and scared to speak right up now, and who also often email me, here’s what I say. Yes, the zombies vastly outnumber us, but on the other hand, they’re zombies. Some of the zombies know longer words than others, but so far, not one has turned out to have a worldview terribly different from that of the image at the top of this post.
I’ll keep the comments closed, for much the same reasons I did in my last post. Namely, while there are many people of all opinions and backgrounds with whom one can productively discuss these things, there are many more with whom one can’t. Furthermore, experience has shown that the latter can disguise themselves as the former for days on end, and thereby execute a denial-of-service attack on any worthwhile and open public discussion.
Addendum: The troll who sent the antisemitic image now says that he regrets and apologizes for it, and that he’s going to read books on Jewish history to understand his error. I’ll believe that when he actually sends me detailed book reports or other evidence, but just wanted to update.
2025-08-29 06:29:03
Suppose a man has already murdered most of your family, including several of your children, for no other reason than that he believes your kind doesn’t deserve to exist on earth. The murderer was never seriously punished for this, because most of your hometown actually shared his feelings about your family. They watched the murders with attitudes ranging from ineffectual squeamishness to indifference to unconcealed glee.
Now the man has kidnapped your last surviving child, a 9-year-old girl, and has tied her screaming to train tracks. You can pull a lever to divert the train and save your daughter. But there’s a catch, as there always is in these moral dilemmas: namely, the murderer has also tied his own five innocent children to the tracks, in such a way that, if you divert the train, then it will kill his children. What’s more, the murderer has invited the entire town to watch you, pointing and screaming “SHAME!!” as you agonize over your decision. He’s persuaded the town that, if you pull the lever, then having killed five of his children to save only one of yours, you’re a far worse murderer than he ever was. You’re so evil, in fact, that he’s effectively cleansed of all guilt for having murdered most of your family first, and the town is cleansed of all guilt for having cheered that. Nothing you say can possibly convince the town otherwise.
The question is, what do you do?
Zionism, to define it in one sentence, is the proposition that, in the situation described, you have not merely a right but a moral obligation to pull the lever—and that you can do so with your middle finger raised high to the hateful mob. Zionism is the belief that, while you had nothing against the murderer’s children, while you would’ve wanted them to grow up in peace and happiness, and while their anguished screams will weigh on your conscience forever, as your children’s screams never weighed on the murderer’s conscience, or on the crowd’s—even so, the responsibility for those children’s deaths rests with their father for engineering this whole diabolical situation, not with you. Zionism is the idea that the correct question here is the broader one: “which choice will bring more righteousness into the world, which choice will better embody the principle that no one’s children are to be murdered going forward?” rather than the narrowly utilitarian question, “which choice will lead to fewer children getting killed right this minute?” Zionism is the conviction that, if most of the world fervently believes otherwise, than most of the world is mistaken—as the world has been mistaken again and again about the biggest ethical questions all through the millennia.
Zionism, so defined, is the deepest moral belief that I have. It’s deeper than any of my beliefs about “politics” in the ordinary sense. Ironically, it’s even deeper than my day-to-day beliefs about the actual State of Israel and its neighbors. I might, for example, despise Benjamin Netanyahu and his ministers, might consider them incompetent and venal, might sympathize with the protesters who’ve filled the streets of Tel Aviv to demand their removal. Even so, when the murderer ties my child to the train tracks and the world cheers the murderer on, not only will I pull the lever myself, I’ll want Benjamin Netanyahu to pull the lever if he gets to it first.
Crucially, everything worthwhile in my life came when, and only when, I chose to be “Zionist” in this abstract sense: that is, steadfast in my convictions even in the face of a jeering mob. As an example, I was able to enter college three years early, which set the stage for all the math and science I later did, only because I finally said “enough” to an incompetent school system where I was bullied and prevented from learning, and to teachers and administrators whose sympathies lay with the bullies. I’ve had my successes in quantum computing theory only because I persisted in what at the time was a fairly bizarre obsession, rather than working on topics that almost everyone around me considered safer, more remunerative, and more sensible.
And as the world learned a decade ago, I was able to date, get married, and have a family, only because I finally rejected what I took to be the socially obligatory attitude for male STEM nerds like me—namely, that my heterosexuality was inherently gross, creepy, and problematic, and that I had a moral obligation never to express romantic interest to women. Yes, I overestimated the number of people who ever believed that, but the fact that it was clearly a nonzero number had been deterrent enough for me. Crucially, I never achieved what I saw for years as my only hope in life, to seek out those who believed my heterosexuality was evil and argue them out of their belief. Instead I simply … well, I raised a middle finger to the Andrea Dworkins and Arthur Chus and Amanda Marcottes of the world. I went Deep Zionist on them. I asked women out, and some of those women (not having gotten the memo that I was “problematic,” gross, and worthless) said yes, and one of them became my wife and the mother of my children.
Today, because of the post-October-7 public stands I’ve taken in favor of Israel’s continued existence, I deal with emails and social media posts day after day calling me a genocidal baby-killing monster. I’ve lost perhaps a dozen friends (while retaining hundreds more friends, and gaining some new ones). The haters’ thought appears to be that, if they can just raise the social cost high enough, I’ll finally renounce my Zionist commitments and they can notch another win. In this, they oddly mirror Hamas, Hezbollah, and the IRGC, who think that, if they can just kill and maim enough Israelis, the hated “settler-colonialist rats” will all scurry back to Poland or wherever else they came from (best not to think too hard about where they did come from, what was done to them in those places, how the Palestinian Arabs of the time felt about what was done to them, or how the survivors ended up making a last stand in their ancestral home of Israel—even afterward, repeatedly holding out olive branches that were met time after time with grenades).
Infamously, Israel’s enemies have failed to understand for a century that, the more they rape and murder, the more Zionist the hated Zionists will become, because unlike the French in Algeria or whatever, most of the Zionists have no other land to go back to: this is it for them. In the same way, my own haters don’t understand that, the more they despise me for being myself, the more myself I’ll be, because I have no other self to turn into.
I’m not opening the comments on this post, because there’s nothing here to debate. I’m simply telling the world my moral axioms. If I wrote these words, then turned to pleading with commenters who hated me because of them, then I wouldn’t really have meant the words, would I?
To my hundreds of dear friends and colleagues who’ve stood by me the past two years, to the Zionists and even just sympathetic neutrals who’ve sent me countless messages of support, but who are too afraid (and usually, too junior in their careers) to speak up in public themselves: know that I’ll use the protections afforded by my privileged position in life to continue speaking on your behalf. Know that I’m infinitely grateful, that you give me strength, and that if I can give you a nanoparticle of strength back to you, then my entire life wasn’t in vain. And if I go silent on this stuff from time to time, for the sake of my mental health, or to spend time on quantum computing research or my kids or the other things that bring me joy—never take that to mean that I’ve capitulated to the haters.
To the obsessive libelers, the Peter Woits and other snarling nobodies, the self-hating Jews, and those who’d cheer to see Israel “decolonized” and my friends and family there murdered, I say—well, I don’t say anything; that’s the point! This is no longer a debate; it’s a war, and I’ll simply stand my ground as long as I’m able. Someday I might forgive the Gentiles among you if you ever see the light, if you ever realize how your unreflective, social-media-driven “anti-fascism” led you to endorse a program that leads to the same end as the original Nazi one. The Jews among you I’ll never forgive, because you did know better, and still chose your own comfort over the physical survival of your people.
It might as well be my own hand on the madman’s lever—and yet, while I grieve for all innocents, my soul is at peace, insofar as it’s ever been at peace about anything.
Update (Aug. 29): This post was born of two years of frustration. It was born of trying, fifty or a hundred times since October 7, to find common ground with the anti-Zionists who emailed me, messaged me, etc.—“hey, obviously neither of us wants any children killed or starved, we both have many bones to pick with the current Israeli government, but surely we at least agree on the necessity of defeating Hamas, right? right??“—only to discover, again and again, that the anti-Zionists had no interest in such common ground. With the runaway success of the global PR campaign against Israel—i.e., of Sinwar’s strategy—and with the rise of figures like Mamdani (and his right-wing counterparts) all over the Western world, anti-Zionists smell blood in the water today. And so, no matter how reasonable they presented themselves at first, eventually they’d come out with “why can’t the Jews just go back to Germany and Poland?” or “the Holocaust was just one more genocide among many; it doesn’t deserve any special response,” or “why can’t we dismantle Israel and have a secular state, with a Jewish minority and a majority that’s sworn to kill all Jews as soon as possible?” And then I realize, with a gasp, that we Jews really are mostly on our own in a cruel and terrifying world—just like we’ve been throughout history.
To say that this experience radicalized me would be an understatement. Indeed, my experience has been that even most Israelis, who generally have far fewer illusions than we diaspora Jews, don’t understand the vastness of the chasm that’s formed. They imagine that they can have a debate with outsiders similar to the debates playing out within Israel—one that presupposes basic factual knowledge and the parameters of the problem (e.g., clearly we can’t put 7 million Jews under the mercy of Hamas). The rationale for Zionism itself feels so obvious to them as to be cringe. Except that, to the rest of the world, it isn’t.
We’re not completely on our own though. There remain decent people of every background, who understand the stakes and feel the weight of history—and I regularly hear from them. And whatever your criticisms of Israel’s current tactics, so long as you accept the almost comically overwhelming historical case for the necessity of Jewish self-defense, this post wasn’t aimed at you, and you and I probably could discuss these matters. It’s just that the anti-Zionists scream so loudly, suck up so much oxygen, that we definitely can’t discuss them in public. Maybe in person sometime, face to face.
2025-08-14 08:50:41
(1) My 8-year-old son asked me last week, “daddy, did you hear that GPT-5 is now out?” So yes, I’m indeed aware that GPT-5 is now out! I’ve just started playing around with it. For detailed reports on what’s changed and how impressive it is compared to previous models, see for example Zvi #1, #2, #3. Briefly, it looks like there are major reductions in hallucinations and sycophancy, and improvements in practical usefulness for coding and other tasks, even while the “raw intelligence” is unlikely to blow away someone who was already well-acquainted with o3 and Opus 4 other state-of-the-art models, the way ChatGPT and then GPT-4 blew away people who had no idea what was possible in late 2022 and early 2023. Partly how impressive a result you see depends on which of several GPT-5 models your query gets routed to, which you don’t entirely control. Anyway, there’s grist here for the people who claim that progress toward AGI is slowing down, but also grist for the people who claim that it continues pretty much as expected within our post-ChatGPT reality!
(2) In other belated news, OpenAI and DeepMind (and then, other companies) announced that they achieved Gold Medal performance on the International Math Olympiad, by solving 5 of the 6 problems (there was one problem, the 6th and hardest, that all of the AIs struggled with). Most importantly, this means that I’ve won $100 from my friend Ernest Davis, AI expert at NYU, who bet me $100 that no AI would earn a Gold Medal at the International Math Olympiad by December 4, 2026. Even though I’m normally risk-averse and reluctant to take bets, I considered this one to be extremely safe, and indeed I won it with more than a year to spare.
(3) I’ve signed an open letter to OpenAI, along with many of my fellow former OpenAI employees as well as distinguished scientists and writers (Geoffrey Hinton, Stuart Russell, Sheldon Glashow, Sean Carroll, Matt Yglesias…), asking for more transparency about OpenAI’s continuing efforts to change its own structure. The questions basically ask OpenAI to declare, in writing, whether it has or hasn’t now completely abandoned the original nonprofit goals with which the organization was founded in 2015.
(4) At Lighthaven, the rationalist meeting space in Berkeley that I recently visited (and that our friend Cade Metz recently cast aspersions on in the New York Times), there’s going to be a writer’s residency called Inkhaven for the whole month of November. The idea—which I love—is that you either write a new blog post every day, or else you get asked to leave (while you also attend workshops, etc. to improve your writing skills). I’d attend myself for the month if teaching and family obligations didn’t conflict; someone standing over me with a whip to make me write is precisely what I need these days! As it is, I’m one of the three advisors to Inkhaven, along with Scott Alexander and Gwern, and I’ll be visiting for a long weekend to share my blogging wisdom, such as I have. Apply now if you’re interested!
(5) Alas, the Springer journal Frontiers of Computer Science has published a nonsense paper, entitled “SAT requires exhaustive search,” claiming to solve (or dissolve, or reframe, or something) the P versus NP problem. It looks indistinguishable from the stuff I used to get in my inbox every week—and now, in the ChatGPT era, get every day. That this was published indicates a total breakdown of the peer review process. Worse, when Eric Allender, Ryan Williams, and others notified the editors of this, asking for the paper to be retracted, the editor-in-chief declined to do so: see this guest post on Lance’s blog for a detailed account. As far as I’m concerned, Frontiers of Computer Science has now completely discredited itself as a journal; publication there means nothing more than publication in viXra. Minus 10 points for journals themselves as an institution, plus 10 points for just posting stuff online and letting it be filtered by experts who care.
(6) Uma Girish and Rocco Servedio released an arXiv preprint called Forrelation is Extremally Hard. Recall that, in the Forrelation problem, you’re given oracle access to two n-bit Boolean functions f and g, and asked to estimate the correlation between f and the Fourier transform of g. I introduced this problem in 2009, as a candidate for an oracle separation between BQP and the polynomial hierarchy—a conjecture that Ran Raz and Avishay Tal finally proved in 2018. What I never imagined was that Forrelation could lead to an oracle separation between EQP (that is, Exact Quantum Polynomial Time) and the polynomial hierarchy. For that, I thought you’d need to go back to the original Recursive Fourier Sampling problem of Bernstein and Vazirani. But Uma and Rocco show, using “bent Boolean functions” (get bent!) and totally contrary to my intuition, that the exact (zero-error) version of Forrelation is already classically hard, taking Ω(2n/4) queries by any randomized algorithm. They leave open whether exact Forrelation needs ~Ω(2n/2) randomized queries, which would match the upper bound, and also whether exact Forrelation is not in PH.
(7) The Google quantum group, to little fanfare, published a paper entitled Constructive interference at the edge of quantum ergodic dynamics. Here, they use their 103-qubit superconducting processor to measure Out-of-Time-Order Correlators (OTOCs) in a many-body scrambling process, and claim to get a verifiable speedup over the best classical methods. If true, this is a great step toward verifiable quantum supremacy for a useful task, for some definition of “useful.”
(8) Last night, on the arXiv, the team at USTC in China reported that it’s done Gaussian BosonSampling with 3,050 photons and 8,176 modes. They say that this achieves quantum supremacy, much more clearly than any previous BosonSampling demonstration, beating (for example) all existing simulations based on tensor network contraction. Needless to say, this still suffers from the central problem of all current sampling-based quantum supremacy experiments, namely the exponential time needed for direct classical verification of the outputs.