# A detective with a quantum helper

Have you ever wanted to be incredibly perceptive and make far-reaching deductions about people? I have always been fascinated by spy stories, and how the main character in them notices tiny details of his surroundings to navigate life-or-death situations. This skill seems out of reach for us normal people; you have to be “a high-functioning sociopath” to memorize all existing data on behavior, clothes choices and forensic science. Of course I’m referring to:

Yet in the not too distant future, a computer may help you become a brilliant detective (or a scheming villain) yourself! The first step is noticing the details, which is known in machine learning as the classification task. Here is a pioneering work that somewhat resembles the above picture, only it’s done by a computer:

The task for the computer here was to produce a verbal description of the image. There are thousands of words in the vocabulary, and a computer has to try them in different combinations to make a sensible sentence. There is no way a computer can be given an exhaustive list of correct sentences with examples of images for each. That kind of list would be a database bigger than the earth (as one can see just by counting the number of combinations). So to train the computer to use language like in a picture above, one only possesses a limited set of examples – maybe a few thousand pictures with descriptions. Yet we as humans are capable of learning from just seeing a few examples, by noticing the repeating patterns. So the computer can do the same! The score next to each word above is an estimate based on those few thousand examples of how relevant is the word “tennis” or “woman” to what’s in the box on the image. The algorithm produces possible sentences, scores them, and then selects the sentence with the highest total score.

Once the classification task is done, one needs to use all the collected information to make a prediction – as Sherlock is able to point out the most probable motive in the first picture, we also want to predict a piece of very personal information: we’d like to know how to start up a conversation with that tennis player.

Humans are actually good at classification tasks: with luck, we can notice and type in our cellphone all the details the predictor will need, like brand of clothing, hair color, height… though computers recently became better than humans at facial expression recognition, so we don’t have to trust ourselves on that anymore. Finally, when all the data is collected, most humans will still say only generic advice to you on conversation starters. Which means we are very bad at prediction tasks. We don’t notice the hidden dependencies between brand of clothes and sense of humor. But such information may not hide from the all-seeing eye of the machine learning algorithm! So expect your cellphones to give you dating advice within 10 years…

Now how do quantum computers come into play? Well if you look at your search results, they are still pretty irrelevant most of the time. Imagine you used them as conversation starters – you’ll embarrass yourself 9 out of 10 times! To make this better, a certain company needs more memory and processing power. Yet most advanced deep learning routines remain out of reach, just because there are exponentially many hidden dependencies one would need to try and reject before the algorithm finds the right predictor. So a certain company turns to us, quantum computing people, as we deal with exponentially hard problems notoriously well! And indeed, quantum algorithms make some of the machine learning routines exponentially faster – see this Quantum Machine Learning article, as well as a talk by Seth Lloyd for technical details. Some anonymous stock trader is already trying to intimidate their fellow quants (quantitative analysts) by calling the top trading system “Quantum machine learning”. I think we should appreciate his sense of humor and invest into his algorithm as soon as Quantiacs.com opens such functionality. Or we could invest in Teagan from Caltech – her code recently won the futures contest on the same website.

# When I met with Steven Spielberg to talk about Interstellar

Today I had the awesome and eagerly anticipated privilege of attending a screening of the new film Interstellar, directed by Christopher Nolan. One can’t help but be impressed by Nolan’s fertile visual imagination. But you should know that Caltech’s own Kip Thorne also had a vital role in this project. Indeed, were there no Kip Thorne, Interstellar would never have happened.

On June 2, 2006, I participated in an unusual one-day meeting at Caltech, organized by Kip and the movie producer Lynda Obst (Sleepless in Seattle, Contact, The Invention of Lying, …). Lynda and Kip, who have been close since being introduced by their mutual friend Carl Sagan decades ago, had conceived a movie project together, and had collaborated on a “treatment” outlining the story idea. The treatment adhered to a core principle that was very important to Kip — that the movie be scientifically accurate. Though the story indulged in some wild speculations, at Kip’s insistence it skirted away from any flagrant violation of the firmly established laws of Nature. This principle of scientifically constrained speculation intrigued Steven Spielberg, who was interested in directing.

The purpose of the meeting was to brainstorm about the story and the science behind it with Spielberg, Obst, and Thorne. A remarkable group assembled, including physicists (Andrei Linde, Lisa Randall, Savas Dimopoulos, Mark Wise, as well as Kip), astrobiologists (Frank Drake, David Grinspoon), planetary scientists (Alan Boss, John Spencer, Dave Stevenson), and psychologists (Jay Buckey, James Carter, David Musson). As we all chatted and got acquainted, I couldn’t help but feel that we were taking part in the opening scene of a movie about making a movie. Spielberg came late and left early, but spent about three hours with us; he even brought along his Dad (an engineer).

Though the official release of Interstellar is still a few days away, you may already know from numerous media reports (including the cover story in this week’s Time Magazine) the essential elements of the story, which involves traveling through a wormhole seeking a new planet for humankind, a replacement for the hopelessly ravaged earth. The narrative evolved substantially as the project progressed, but traveling through a wormhole to visit a distant planet was already central to the original story.

Inevitably, some elements of the Obst/Thorne treatment did not survive in the final film. For one, Stephen Hawking was a prominent character in the original story; he joined the mission because of his unparalleled expertise at wormhole transversal, and Stephen’s ALS symptoms eased during prolonged weightlessness, only to recur upon return to earth gravity. Also, gravitational waves played a big part in the treatment; in particular the opening scene depicted LIGO scientists discovering the wormhole by detecting the gravitational waves emanating from it.

There was plenty to discuss to fill our one-day workshop, including: the rocket technology needed for the trip, the strong but stretchy materials that would allow the ship to pass through the wormhole without being torn apart by tidal gravity, how to select a crew psychologically fit for such a dangerous mission, what exotic life forms might be found on other worlds, how to communicate with an advanced civilization which resides in a higher dimensional bulk rather than the three-dimensional brane to which we’re confined, how to build a wormhole that stays open rather than pinching off and crushing those who attempt to pass through, and whether a wormhole could enable travel backward in time.

Spielberg was quite engaged in our discussions. Upon his arrival I immediately shot off a text to my daughter Carina: “Steven Spielberg is wearing a Brown University cap!” (Carina was a Brown student at the time, as Spielberg’s daughter had been.) Steven assured us of his keen interest in the project, noting wryly that “Aliens have been very good to me,” and he mentioned some of his favorite space movies, which included some I had also enjoyed as a kid, like Forbidden Planet and (the original) The Day the Earth Stood Still. In one notable moment, Spielberg asked the group “Who believes that intelligent life exists elsewhere in the universe?” We all raised our hands. “And who believes that the earth has been visited by extraterrestrial civilizations?” No one raised a hand. Steven seemed struck by our unanimity, on both questions.

I remember tentatively suggesting that the extraterrestrials had mastered M-theory, thus attaining computational power far beyond the comprehension of earthlings, and that they themselves were really advanced robots, constructed by an earlier generation of computers. Like many of the fun story ideas floated that day, this one had no apparent impact on the final version of the film.

Spielberg later brought in Jonah Nolan to write the screenplay. When Spielberg had to abandon the project because his DreamWorks production company broke up with Paramount Pictures (which owned the story), Jonah’s brother Chris Nolan eventually took over the project. Jonah and Chris Nolan transformed the story, but continued to consult extensively with Kip, who became an Executive Producer and says he is pleased with the final result.

Of the many recent articles about Interstellar, one of the most interesting is this one in Wired by Adam Rogers, which describes how Kip worked closely with the visual effects team at Double Negative to ensure that wormholes and rapidly rotating black holes are accurately depicted in the film (though liberties were taken to avoid confusing the audience). The images produced by sophisticated ray tracing computations were so surprising that at first Kip thought there must be a bug in the software, though eventually he accepted that the calculations are correct, and he is still working hard to more fully understand the results.

I can’t give away the ending of the movie, but I can safely say this: When it’s over you’re going to have a lot of questions. Fortunately for all of us, Kip’s book The Science of Interstellar will be available the same day the movie goes into wide release (November 7), so we’ll all know where to seek enlightenment.

In fact on that very same day we’ll be treated to the release of The Theory of Everything, a biopic about Stephen and Jane Hawking. So November 7 is going to be an unforgettable Black Hole Day. Enjoy!

# Apply to join IQIM!

Editor’s Note: Dr. Chandni Usha is an IQIM postdoctoral scholar working with Prof. Eisenstein. We asked her to describe her experience as an IQIM fellow.

Just another day at work!

When I look back at how I ended up here, I find myself in a couple of metastable states. Every state pushed me to newer avenues of knowledge. Interestingly, growing up I never really knew what it was like to be a scientist. I had not watched any of those sci-fi movies or related TV series as a kid. No outreach program ever reached me in my years of schooling! My first career choice was to be a lawyer. But a casual comment by a friend that lawyers are ‘liars’ was strong enough to change my mind. Strangely enough, now the quest is for the truth, in a lab down at the sub-basement of one of the world’s best research institutes.

I did my masters in Physics at this beautiful place called the Indian Institute of Science in Bangalore. I realized that I like doing things with my hands. Fixing broken instruments seemed fun. Every new data point on a plot amused me. It was more than obvious that experimental physics is where my heart was and hence I went on to do a Ph.D. in condensed matter physics. When I decided to apply for postdoctoral positions, an old friend of mine, Debaleena Nandi, told me to look up the IQIM website. That was in November 2012, and I applied for the IQIM postdoctoral fellowship. My stars were probably aligned to be here. Coincidentally, Jim Eisenstein, my adviser, was in India on a sabbatical and I happened to hear him give a talk. It left such a strong impression in my mind that I was willing to give up on a trip to Europe for an interview the next day had he offered me a position. We spoke about possible problems, but no offer was in sight and hence I did travel to Europe with my mind already at Caltech. IQIM saved me from my dilemma when they offered me the fellowship a few days later.

Now, why choose IQIM! Reason number one was Jim. And reason number two was this blog which brought in this feeling that there exists a community here; where experimentalists and theorists could share their ideas and grow together in a symbiotic manner. My first project was with an earlier postdoc, Erik Henriksen, who is now a faculty at Washington University in St. Louis. It was based on a proposal by fellow IQIM professor Jason Alicea which involved decorating a film of graphene with a certain heavy metal adatom. Jason’s prediction was that if you choose the right adatom, it could endow some of its unique properties such as strong spin-orbit coupling to the underlying graphene sheet. One can thus engineer graphene to what is called a topological insulator where only the edges of the graphene sheet conduct. Erik had taken on this task and I tagged along. Working in a very small campus with a close-knit community helps bounce your ideas around others and that’s how this experiment came into being. I found it particularly interesting that Jason and his colleagues often ask us, the experimentalists, whether some of the ideas they have are actually feasible to be performed in a lab!

The IQIM fellowship allows you to work on a variety of fields that come under the common theme of quantum information and matter. In addition to providing an independent funding and research grant, the fellowship offers the flexibility to work with any mentor and even multiple mentors, especially in the theory group. In experimental groups however, that flexibility is limited but not impossible. The fellowship gives you a lot of freedom and encourages collaborations. IQIM theory folks have a very strong and friendly group with a lot of collaborations, to the extent that it is often hard to distinguish the faculty from the postdocs and students.

Apart from a yearly retreat to a beautiful resort in Lake Arrowhead, the social life at IQIM is further enhanced through the Friday seminars where you get to hear about the work from postdocs and graduate students from IQIM, as well as other universities. IQIM’s outreach activities have been outstanding. A quick look at this blog will take you from the PhD Comics animations, to teaching kids quantum mechanics through Miinecraft, to hosting middle school students at the InnoWorks academy and a host of other activities. This note will not be complete without mentioning about our repeated efforts to attract women candidates. My husband lives in India, and I live right across the globe, all for the love of science. I am not alone in this respect as we have two more women postdocs at IQIM who have similar stories to tell. So, if you are a woman and wish to pursue a quality research program, this is the place to be, for together we can bring change.

Now that I have convinced you that IQIM is something not to be missed, kindly spread the word. And if you are looking for an awesome opportunity to work at Caltech, get your CV and research statement and apply for the fellowships before Dec 5, 2014!

# Macroscopic quantum teleportation: the story of my chair

In the summer of 2000, a miracle occurred: The National Science Foundation decided to fund a new Institute for Quantum Information at Caltech with a 5 million dollar award from their Information Technology Research program. I was to be the founding director of the IQI.

Jeff Kimble explained to me why we should propose establishing the IQI. He knew I had used my slice of our shared DARPA grant to bring Alexei Kitaev to Caltech as a visiting professor, which had been wonderful. Recalling how much we had both benefited from Kitaev’s visit, Jeff remarked emphatically that “This stuff’s not free.” He had a point. To have more fun we’d need more money. Jeff took the lead in recruiting a large team of Caltech theorists and experimentalists to join the proposal we submitted, but the NSF was primarily interested in supporting the theory of quantum computation rather than the experimental part of the proposal. That was how I wound up in charge, though I continued to rely on Jeff’s advice and support.

This was a new experience for me and I worried a lot about how directing an institute would change my life. But I had one worry above all: space. We envisioned a thriving institute brimming over with talented and enthusiastic young scientists and visitors drawn from the physics, computer science, and engineering communities. But how could we carve out a place on the Caltech campus where they could work and interact?

To my surprise and delight, Jeff and I soon discovered that someone else at Caltech shared our excitement over the potential of IQI — Richard Murray, who was then the Chair of Caltech’s Division of Engineering and Applied Science. Richard arranged for the IQI to occupy office space in Steele Laboratory and some space we could configure as we pleased in Jorgensen Laboratory. The hub of the IQI became the lounge in Jorgensen, which we used for our seminar receptions, group meetings, and innumerable informal discussions, until our move to the beautiful Annenberg Center when it opened in 2009.

I sketched a rough plan for the Jorgensen layout, including furniture for the lounge. The furniture, I was told, was “NIC”. Though I was too embarrassed to ask, I eventually inferred this meant “Not in Contract” — I would need to go furniture shopping, one of my many burgeoning responsibilities as Director.

By this time, Ann Harvey was in place as IQI administrator, a huge relief. But furniture was something I thought I knew about, because I had designed and furnished a common area for the particle theory group a couple of years earlier. As we had done on that previous occasion, my wife Roberta and I went to Krause’s Sofa Factory to order a custom-made couch, love seat, and lounge chair, in a grayish green leather which we thought would blend well with the carpeting.

Directing an institute is not as simple as it sounds, though. Before the furniture was delivered, Krause’s declared bankruptcy! We had paid in full, but I had some anxious moments wondering whether there would be a place to sit down in the IQI lounge. In the end, after some delay, our furniture was delivered in time for the grand opening of the new space in September 2001. A happy ending, but not really the end of the story.

Before the move to Annenberg in 2009, I ordered furniture to fill our (much smaller) studio space, which became the new IQI common area. The Jorgensen furniture was retired, and everything was new! It was nice … But every once in a while I felt a twinge of sadness. I missed my old leather chair, from which I had pontificated at eight years worth of group meetings. That chair and I had been through a lot together, and I couldn’t help but feel that my chair’s career had been cut short before its time.

I don’t recall mentioning these feelings to anyone, but someone must have sensed by regrets. Because one day not long after the move another miracle occurred … my chair was baaack! Sitting in it again felt … good. For five years now I’ve been pontificating from my old chair in our new studio, just like I used to. No one told me how my chair had been returned to me, and I knew better than to ask.

My chair today. Like me, a bit worn but still far from retirement.

Eventually the truth comes out. At my 60th birthday celebration last year, Stephanie Wehner and Darrick Chang admitted to being the perpetrators, and revealed the whole amazing story in their article on “Macroscopic Quantum Teleportation” in a special issue of Nature Relocations. Their breakthrough article was enhanced by Stephanie’s extraordinary artwork, which you really have to see to believe. So if your curiosity is piqued, please follow this link to find out more.

Why, you may wonder, am I reminiscing today about the story of my chair? Well, is an excuse really necessary? But if you must know, it may be because, after two renewals and 14 years of operation, I submitted the IQI Final Report to the NSF this week. Don’t worry — the Report is not really Final, because the IQI has become part of an even grander vision, the IQIM (which has given birth to this blog among other good things). Like my chair, the IQI is not quite what it was, yet it lives on.

The nostalgic feelings aroused by filing the Final Report led me to reread the wonderful volume my colleagues put together for my birthday celebration, which recounts not only the unforgettable exploits of Stephanie and Darrick, but many other stories and testimonials that deeply touched me.

Browsing through that book today, one thing that struck me is the ways we sometimes have impact on others without even being aware of it. For example, Aram Harrow, Debbie Leung, Joe Renes and Stephanie all remember lectures I gave when they were undergraduate students (before I knew them), which might have influenced their later research careers. Knowing this will make it a little harder to say no the next time I’m invited to give a talk. Yaoyun Shi has vivid memories of the time I wore my gorilla mask to the IQI seminar on Halloween, which inspired him to dress up as “a butcher threatening to cut off the ears of my students with a bloody machete if they were not listening,” thus boosting his teaching evaluations. And Alexios Polychronakos, upon hearing that I had left particle theory to pursue quantum computing, felt it “was a bit like watching your father move to Las Vegas and marry a young dancer after you leave for college,” while at the same time he appreciated “that such reinventions are within the spectrum of possibilities for physicists who still have a pulse.”

I’m proud of what the IQI(M) has accomplished, but we’re just getting started. After 14 years, I still have a pulse, and my chair has plenty of wear left. Together we look forward to many more years of pontification.

# John Preskill and the dawn of the entanglement frontier

Editor’s Note: John Preskill’s recent election to the National Academy of Sciences generated a lot of enthusiasm among his colleagues and students. In an earlier post today, famed Stanford theoretical physicist, Leonard Susskind, paid tribute to John’s early contributions to physics ranging from magnetic monopoles to the quantum mechanics of black holes. In this post, Daniel Gottesman, a faculty member at the Perimeter Institute, takes us back to the formative years of the Institute for Quantum Information at Caltech, the precursor to IQIM and a world-renowned incubator for quantum information and quantum computation research. Though John shies away from the spotlight, we, at IQIM, believe that the integrity of his character and his role as a mentor and catalyst for science are worthy of attention and set a good example for current and future generations of theoretical physicists.

Preskill’s legacy may well be the incredible number of preeminent research scientists in quantum physics he has mentored throughout his extraordinary career.

When someone wins a big award, it has become traditional on this blog for John Preskill to write something about them. The system breaks down, though, when John is the one winning the award. Therefore I’ve been brought in as a pinch hitter (or should it be pinch lionizer?).

The award in this case is that John has been elected to the National Academy of Sciences, along with Charlie Kane and a number of other people that don’t work on quantum information. Lenny Susskind has already written about John’s work on other topics; I will focus on quantum information.

On the research side of quantum information, John is probably best known for his work on fault-tolerant quantum computation, particularly topological fault tolerance. John jumped into the field of quantum computation in 1994 in the wake of Shor’s algorithm, and brought me and some of his other grad students with him. It was obvious from the start that error correction was an important theoretical challenge (emphasized, for instance, by Unruh), so that was one of the things we looked at. We couldn’t figure out how to do it, but some other people did. John and I embarked on a long drawn-out project to get good bounds on the threshold error rate. If you can build a quantum computer with an error rate below the threshold value, you can do arbitrarily large quantum computations. If not, then errors will eventually overwhelm you. Early versions of my project with John suggested that the threshold should be about $10^{-4}$, and the number began floating around (somewhat embarrassingly) as the definitive word on the threshold value. Our attempts to bound the higher-order terms in the computation became rather grotesque, and the project proceeded very slowly until a new approach and the recruitment of Panos Aliferis finally let us finish a paper with a rigorous proof of a slightly lower threshold value.

Meanwhile, John had also been working on topological quantum computation. John has already written about his excitement when Kitaev visited Caltech and talked about the toric code. The two of them, plus Eric Dennis and Andrew Landahl, studied the application of this code for fault tolerance. If you look at the citations of this paper over time, it looks rather … exponential. For a while, topological things were too exotic for most quantum computer people, but over time, the virtues of surface codes have become obvious (apparently high threshold, convenient for two-dimensional architectures). It’s become one of the hot topics in recent years and there are no signs of flagging interest in the community.

John has also made some important contributions to security proofs for quantum key distribution, known to the cognoscenti just by its initials. QKD allows two people (almost invariably named Alice and Bob) to establish a secret key by sending qubits over an insecure channel. If the eavesdropper Eve tries to live up to her name, her measurements of the qubits being transmitted will cause errors revealing her presence. If Alice and Bob don’t detect the presence of Eve, they conclude that she is not listening in (or at any rate hasn’t learned much about the secret key) and therefore they can be confident of security when they later use the secret key to encrypt a secret message. With Peter Shor, John gave a security proof of the best-known QKD protocol, known as the “Shor-Preskill” proof. Sometimes we scientists lack originality in naming. It was not the first proof of security, but earlier ones were rather complicated. The Shor-Preskill proof was conceptually much clearer and made a beautiful connection between the properties of quantum error-correcting codes and QKD. The techniques introduced in their paper got adopted into much later work on quantum cryptography.

Collaborating with John is always an interesting experience. Sometimes we’ll discuss some idea or some topic and it will be clear that John does not understand the idea clearly or knows little about the topic. Then, a few days later we discuss the same subject again and John is an expert, or at least he knows a lot more than me. I guess this ability to master
topics quickly is why he was always able to answer Steve Flammia’s random questions after lunch. And then when it comes time to write the paper … John will do it. It’s not just that he will volunteer to write the first draft — he keeps control of the whole paper and generally won’t let you edit the source, although of course he will incorporate your comments. I think this habit started because of incompatibilities between the TeX editor he was using and any other program, but he maintains it (I believe) to make sure that the paper meets his high standards of presentation quality.

This also explains why John has been so successful as an expositor. His
lecture notes for the quantum computation class at Caltech are well-known. Despite being incomplete and not available on Amazon, they are probably almost as widely read as the standard textbook by Nielsen and Chuang.

Before IQIM, there was IQI, and before that was QUIC.

He apparently is also good at writing grants. Under his leadership and Jeff Kimble’s, Caltech has become one of the top places for quantum computation. In my last year of graduate school, John and Jeff, along with Steve Koonin, secured the QUIC grant, and all of a sudden Caltech had money for quantum computation. I got a research assistantship and could write my thesis without having to worry about TAing. Postdocs started to come — first Chris Fuchs, then a long stream of illustrious others. The QUIC grant grew into IQI, and that eventually sprouted an M and drew in even more people. When I was a student, John’s group was located in Lauritsen with the particle theory group. We had maybe three grad student offices (and not all the students were working on quantum information), plus John’s office. As the Caltech quantum effort grew, IQI acquired territory in another building, then another, and then moved into a good chunk of the new Annenberg building. Without John’s efforts, the quantum computing program at Caltech would certainly be much smaller and maybe completely lacking a theory side. It’s also unlikely this blog would exist.

The National Academy has now elected John a member, probably more for his research than his twitter account (@preskill), though I suppose you never know. Anyway, congratulations, John!

-D. Gottesman

# Of magnetic monopoles and fast-scrambling black holes

Editor’s Note: On April 29th, 2014, the National Academy of Sciences announced the new electees to the prestigious organization. This was an especially happy occasion for everyone here at IQIM, since the new members included our very own John Preskill, Richard P. Feynman Professor of Theoretical Physics and regular blogger on this site. A request was sent to Leonard Susskind, a close friend and collaborator of John’s, to take a trip down memory lane and give the rest of us a glimpse of some of John’s early contributions to Physics. John, congratulations from all of us here at IQIM.

John Preskill was elected to the National Academy of Sciences, an event long overdue. Perhaps it took longer than it should have because there is no way to pigeon-hole him; he is a theoretical physicist, and that’s all there is to it.

John has long been one of my heroes in theoretical physics. There is something very special about his work. It has exceptional clarity, it has vision, it has integrity—you can count on it. And sometimes it has another property: it can surprise. The first time I heard his name come up, sometime around 1979, I was not only surprised; I was dismayed. A student whose name I had never heard of, had uncovered a serious clash between two things, both of which I deeply wanted to believe in. One was the Big-Bang theory and the other was the discovery of grand unified particle theories. Unification led to the extraordinary prediction that Dirac’s magnetic monopoles must exist, at least in principle. The Big-Bang theory said they must exist in fact. The extreme conditions at the beginning of the universe were exactly what was needed to create loads of monopoles; so many that they would flood the universe with too much mass. John, the unknown graduate student, did a masterful analysis. It left no doubt that something had to give. Cosmology gave. About a year later, inflationary cosmology was discovered by Guth who was in part motivated by Preskill’s monopole puzzle.

John’s subsequent career as a particle physicist was marked by a number of important insights which often had that surprising quality. The cosmology of the invisible axion was one. Others had to do with very subtle and counterintuitive features of quantum field theory, like the existence of “Alice strings”. In the very distant past, Roger Penrose and I had a peculiar conversation about possible generalizations of the Aharonov-Bohm effect. We speculated on all sorts of things that might happen when something is transported around a string. I think it was Roger who got excited about the possibilities that might result if a topological defect could change gender. Alice strings were not quite that exotic, only electric charge flips, but nevertheless it was very surprising.

John of course had a long standing interest in the quantum mechanics of black holes: I will quote a passage from a visionary 1992 review paper, “Do Black Holes Destroy Information?

“I conclude that the information loss paradox may well presage a revolution in fundamental physics.”

At that time no one knew the answer to the paradox, although a few of us, including John, thought the answer was that information could not be lost. But almost no one saw the future as clearly as John did. Our paths crossed in 1993 in a very exciting discussion about black holes and information. We were both thinking about the same thing, now called black hole complementarity. We were concerned about quantum cloning if information is carried by Hawking radiation. We thought we knew the answer: it takes too long to retrieve the information to then be able to jump into the black hole and discover the clone. This is probably true, but at that time we had no idea how close a call this might be.

It took until 2007 to properly formulate the problem. Patrick Hayden and John Preskill utterly surprised me, and probably everyone else who had been thinking about black holes, with their now-famous paper “Black Holes as Mirrors.” In a sense, this paper started a revolution in applying the powerful methods of quantum information theory to black holes.

We live in the age of entanglement. From quantum computing to condensed matter theory, to quantum gravity, entanglement is the new watchword. Preskill was in the vanguard of this revolution, but he was also the teacher who made the new concepts available to physicists like myself. We can now speak about entanglement, error correction, fault tolerance, tensor networks and more. The Preskill lectures were the indispensable source of knowledge and insight for us.

Congratulations John. And congratulations NAS.

-L. S.

# Tsar Nikita and His Scientists

Once upon a time, a Russian tsar named Nikita had forty daughters:

Every one from top to toe
Was a captivating creature,
Perfect—but for one lost feature.

So wrote Alexander Pushkin, the 19th-century Shakespeare who revolutionized Russian literature. In a rhyme, Pushkin imagined forty princesses born without “that bit” “[b]etween their legs.” A courier scours the countryside for a witch who can help. By summoning the devil in the woods, she conjures what the princesses lack into a casket. The tsar parcels out the casket’s contents, and everyone rejoices.

“[N]onsense,” Pushkin calls the tale in its penultimate line. A “joke.”

The joke has, nearly two centuries later, become reality. Researchers have grown vaginas in a lab and implanted them into teenage girls. Thanks to a genetic defect, the girls suffered from Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome: Their vaginas and uteruses had failed to grow to maturity or at all. A team at Wake Forest and in Mexico City took samples of the girls’ cells, grew more cells, and combined their harvest with vagina-shaped scaffolds. Early in the 2000s, surgeons implanted the artificial organs into the girls. The patients, the researchers reported in the journal The Lancet last week, function normally.

I don’t usually write about reproductive machinery. But the implants’ resonance with “Tsar Nikita” floored me. Scientists have implanted much of Pushkin’s plot into labs. The sexually deficient girls, the craftsperson, the replacement organs—all appear in “Tsar Nikita” as in The Lancet. In poetry as in science fiction, we read the future.

Though threads of Pushkin’s plot survive, society’s view of the specialist has progressed. “Deep [in] the dark woods” lives Pushkin’s witch. Upon summoning the devil, she locks her cure in a casket. Today’s vagina-implanters star in headlines. The Wall Street Journal highlighted the implants in its front section. Unless the patients’ health degrades, the researchers will likely list last week’s paper high on their CVs and websites.

Much as Dr. Atlántida Raya-Rivera, the paper’s lead author, differs from Pushkin’s witch, the visage of Pushkin’s magic wears the nose and eyebrows of science. When tsars or millenials need medical help, they seek knowledge-keepers: specialists, a fringe of society. Before summoning the devil, the witch “[l]ocked her door . . . Three days passed.” I hide away to calculate and study (though days alone might render me more like the protagonist in another Russian story, Chekhov’s “The Bet”). Just as the witch “stocked up coal,” some students stockpile Red Bull before hitting the library. Some habits, like the archetype of the wise woman, refuse to die.

From a Russian rhyme, the bones of “Tsar Nikita” have evolved into cutting-edge science. Pushkin and the implants highlight how attitudes toward knowledge have changed, offering a lens onto science in culture and onto science culture. No wonder readers call Pushkin “timeless.”

But what would he have rhymed with “Mayer-Rokitansky-Küster-Hauser”?

“Tsar Nikita” has many nuances—messages about censorship, for example—that I didn’t discuss. To the intrigued, I recommend The Queen of Spades: And selected works, translated by Anthony Briggs and published by Pushkin Press.