Stephen Wiesner (1942-2021)

Photo credit: Lev Vaidman

These have not been an auspicious few weeks for Jewish-American-born theoretical physicists named Steve who made epochal contributions to human knowledge in the late 1960s, and who I had the privilege to get to know a bit when they were old.

This morning, my friend and colleague Or Sattath brought me the terrible news that Stephen Wiesner has passed away in Israel. [Because people have asked: I’ve now also heard directly from Wiesner’s daughter Sarah.]

Decades ago, Wiesner left academia, embraced Orthodox Judaism, moved from the US to Israel, and took up work there as a construction laborer—believing (or so he told me) that manual labor was good for the soul. In the late 1960s, however, Wiesner was still a graduate student in physics at Columbia University, when he wrote Conjugate Coding: arguably the foundational document of the entire field of quantum information science. Famously, this paper was so far ahead of its time that it was rejected over and over from journals, taking nearly 15 years to get published. (Fascinatingly, Gilles Brassard tells me that this isn’t true: it was rejected once, from IEEE Transactions on Information Theory, and then Wiesner simply shelved it.) When it finally appeared, in 1983, it was in SIGACT News—a venue that I know and love, where I’ve published too, but that’s more like the house newsletter for theoretical computer scientists than an academic journal.

But it didn’t matter. By the early 1980s, Wiesner’s ideas had been successfully communicated to Charlie Bennett and Gilles Brassard, who refashioned them into the first scheme for quantum key distribution—what we now call BB84. Even as Bennett and Brassard received scientific acclaim for the invention of quantum cryptography—including, a few years ago, the Wolf Prize (often considered second only to the Nobel Prize), at a ceremony in the Knesset in Jerusalem that I attended—the two B’s were always careful to acknowledge their massive intellectual debt to Steve Wiesner.

Let me explain what Wiesner does in the Conjugate Coding paper. As far as I know, this is the first paper ever to propose that quantum information—what Wiesner called “polarized light” or “spin-1/2 particles” but we now simply call qubits—works differently than classical bits, in ways that could actually be useful for achieving cryptographic tasks that are impossible in a classical world. What could enable these cryptographic applications, wrote Wiesner, is the fact that there’s no physical means for an attacker or eavesdropper to copy an unknown qubit, to produce a second qubit in the same quantum state. This observation—now called the No-Cloning Theorem—would only be named and published in 1982, but Wiesner treats it in his late-1960s manuscript as just obvious background.

Wiesner went further than these general ideas, though, to propose an explicit scheme for quantum money that would be physically impossible to counterfeit—a scheme that’s still of enormous interest half a century later (I teach it every year in my undergraduate course). In what we now call the Wiesner money scheme, a central bank prints “quantum bills,” each of which contains a classical serial number as well as a long string of qubits. Each qubit is prepared in one of four possible quantum states:

  • |0⟩,
  • |1⟩,
  • |+⟩ = (|0⟩+|1⟩)/√2, or
  • |-⟩ = (|0⟩-|1⟩)/√2.

The bank, in a central database, stores the serial number of every bill in circulation, as well as the preparation instructions for each of the bill’s qubits. If you want to verify a bill as genuine—this, as Wiesner knew, is the big drawback—you have to bring it back to the bank. The bank, using its secret knowledge of how each qubit was prepared, measures each qubit in the appropriate basis—the {|0⟩,|1⟩} basis for |0⟩ or |1⟩ qubits, the {|+⟩,|-⟩} basis for |+⟩ or |-⟩ qubits—and checks that it gets the expected outcomes. If even one qubit yields the wrong outcome, the bill is rejected as counterfeit.

Now consider the situation of a counterfeiter, who holds a quantum bill but lacks access to the bank’s secret database. When the counterfeiter tries to copy the bill, they won’t know the right basis in which to measure each qubit—and if they make the wrong choice, then it’s not only that they fail to make a copy; it’s that the measurement destroys even the original copy! For example, measuring a |+⟩ or |-⟩ qubit in the {|0⟩,|1⟩} basis will randomly collapse the qubit to either |0⟩ or |1⟩—so that, when the bank later measures the same qubit in the correct {|+⟩,|-⟩} basis, it will see the wrong outcome, and realize that the bill has been compromised, with 1/2 probability (with the probability increasing to nearly 1 as we repeat across hundreds or thousands of qubits).

Admittedly, the handwavy argument above, which Wiesner offered, is far from a security proof by cryptographers’ standards. In 2011, I pointed that out on StackExchange. My post, I’m happy to say, spurred Molina, Vidick, and Watrous to write a beautiful 2012 paper, where they rigorously proved for the first time that in Wiesner’s money scheme, no counterfeiter consistent with the laws of quantum mechanics can turn a single n-qubit bill into two bills that both pass the bank’s verification with success probability greater than (3/4)n (and this is tight). But the intuition was already clear enough to Wiesner in the 1960s.

In 2003—when I was already a PhD student in quantum information, but incredibly, had never heard of Stephen Wiesner or his role in founding my field—I rediscovered the idea of quantum states |ψ⟩ that you could store, measure, and feed into a quantum computer, but that would be usefully uncopyable. (My main interest was in whether you could create “unpiratable quantum software programs.”) Only in 2006, at the University of Waterloo, did Michele Mosca and his students make the connection for me to quantum money, Stephen Wiesner, and his Conjugate Coding paper, which I then read with amazement—along with a comparably amazing followup work by Bennett, Brassard, Breidbart, and Wiesner.

But it was clear that there was still a great deal to do. Besides unpiratable software, Wiesner and his collaborators had lacked the tools in the early 1980s seriously to tackle the problem of secure quantum money that anybody could verify, not only the bank that had created the money. I realized that, if such a thing was possible at all, then just like unpiratable software, it would require cryptographic hardness assumptions, a restriction to polynomial-time counterfeiters, and (hence) ideas from quantum computational complexity. The No-Cloning Theorem couldn’t do the job on its own.

That realization led to my 2009 paper Quantum Copy-Protection and Quantum Money, and from there, to the “modern renaissance” of Wiesner’s old idea of quantum money, with well over a hundred papers (e.g., my 2012 paper with Paul Christiano, Farhi et al.’s quantum state restoration paper, their quantum money from knots paper, Mark Zhandry’s 2017 quantum lightning paper, Dmitry Gavinsky’s improvement of Wiesner’s scheme wherein the money is verified by classical communication with the bank, Broduch et al.’s adaptive attack on Wiesner’s original scheme, my shadow tomography paper proving the necessity for the bank to keep a giant database in information-theoretic quantum money schemes like Wiesner’s, Daniel Kane’s strange scheme based on modular forms…). The purpose of many of these papers was either to break the quantum money schemes proposed in previous papers, or to patch the schemes that were previously broken.

After all this back-and-forth, spanning more than a decade, I’d say that Wiesner’s old idea of quantum money is now in good enough theoretical shape that the main obstacle to its practical realization is merely the “engineering difficulty”—namely, how to get the qubits in a bill, sitting in your pocket or whatever, to maintain their quantum coherence for more than a few nanoseconds! (Or possibly a few hours, if you’re willing to schlep a cryogenic freezer everywhere you go.) It’s precisely because quantum key distribution doesn’t have this storage problem—because there the qubits are simply sent across a channel and then immediately measured on arrival—that QKD is actually practical today, although the market for it has proven to be extremely limited so far.

In the meantime, while the world waits for the quantum error-correction that could keep qubits alive indefinitely, there’s Bitcoin. The latter perversely illustrates just how immense the demand for quantum money might someday be: the staggering lengths to which people will go, diverting the electricity to power whole nations into mining rigs, to get around our current inability to realize Wiesner’s elegant quantum-mechanical solution to the same problem. When I first learned about Bitcoin, shortly after its invention, it was in the context of: “here’s something I’d better bring up in my lectures on quantum money, in order to explain how much better WiesnerCoin could eventually be, when it’s the year 2200 or whatever and we all have quantum computers wired up by a quantum Internet!” It never occurred to me that I should forget about the year 2200, liquidate my life savings, and immediately buy up all the Bitcoin I could. [Added: I’ve since learned that Wiesner’s daughter Sarah is a professional in the Bitcoin space.]

Photo credit: Or Sattath

In his decades as a construction laborer, Wiesner had (as far as I know) no Internet presence; many of my colleagues didn’t even realize he was still alive. Even then, though, Wiesner never turned his back so far on his previous life, his academic life, that the quantum information faculty at Hebrew University in Jerusalem couldn’t entice him to participate in some seminars there. Those seminars are where I had the privilege to meet and talk to him several times over the last decade. He was thoughtful and kind, listening with interest as I told him how I and others were trying to take quantum money into the modern era by making it publicly verifiable.

I also vividly remember a conversation in 2013 where Steve shared his fears about the American physics establishment and military-industrial complex, and passionately urged me to

  1. quit academia and get a “real job,” and
  2. flee the US immediately and move my family to Israel, because of a wave of fascism and antisemitism that was about to sweep the US, just like with Germany in the 1930s.

I politely nodded along, pointing out that my Israeli wife and I had considered living in Israel but the job opportunities were better in US, silently wondering when Steve had gone completely off his rocker. Today, Steve’s urgent warning about an impending fascist takeover of the US seems … uh, slightly less crazy than in 2013? Maybe, just like with quantum money, Wiesner was simply too far ahead of his time to sound sane.

Wiesner also talked to me about his father, Jerome Wiesner, who was a legendary president of MIT—still spoken about in reverent tones when I taught there—as well as the chief science advisor to John F. Kennedy. One of JFK’s most famous decisions was to override the elder Wiesner’s fervent opposition to sending humans to the moon (Wiesner thought it a waste of money, as robots could do the same science for vastly cheaper).

While I don’t know all the details (I hope someone someday researches it and writes a book), Steve Wiesner made it clear to me that he did not get along with his famous father at all—in fact they became estranged. Steve told me that his embrace of Orthodox Judaism was, at least in part, a reaction against everything his father had stood for, including militant scientific atheism. I suppose that in the 1960s, millions of young Americans defied their parents via sex, drugs, and acoustic guitar; only a tiny number did so by donning tzitzit and moving to Israel to pray and toil with their hands. The two groups of rebels did, however, share a tendency to grow long beards.

Wiesner’s unique, remarkable, uncloneable life trajectory raises the question: who are the young Stephen Wiesners of our time? Will we be faster to recognize their foresight than Wiesner’s contemporaries were to recognize his?

Feel free to share any other memories of Stephen Wiesner or his influence in the comments.

Update (Aug. 14): See also Or Sattath’s memorial post, which (among other things) points out something that my narrative missed: namely, besides quantum money, Wiesner also invented superdense coding in 1970, although he and Bennett only published the idea 22 years later (!).

And I have more photos! Here’s Wiesner with an invention of his and another photo (thanks to his daughter Sarah). Here’s another photo from 1970 and Charlie Bennett’s handwritten notes (!) after first meeting Wiesner in 1970 (thanks to Charlie Bennett).

Another Update: Stephen’s daughter Sarah gave me the following fascinating information to share.

In the 70’s he lived in California where he worked in various Silicon Valley startups while also working weekends as part of a produce (fruits and vegetables) distribution co-op. During this time he became devoted to the ideas of solar energy, clean energy and space migration and exploration. He also became interested in Judaism. He truly wanted to help and make our world more peaceful and safe with his focus being on clean energy and branching out into space. He also believed that instead of fighting over the temple mount in Jerusalem, the Third Temple should be built in outer-space or in a structure above the original spot, an idea he tried to promote to prevent wars over land.

35 Responses to “Stephen Wiesner (1942-2021)”

  1. Partisan Says:

    Sorry to hear about this loss, Scott. Coincidentally, there was a very interesting article in wapo yesterday about another pioneering technologist who suddenly disappeared from public life: .

    It left me wondering the exact same question as you: who should we be paying more attention to now?

  2. HasH Says:

    Sad think he left everything for a religion but as a Revolutionist, I have to respect his rebellion. I did same to my Muslim father’s belief, and he was working in a construction business and I left civil engineering because of him.. What a similar life, except I am trolling around, reading GENIUS people (real miracles of cosmos).

    Rest in Peace Sir!

  3. asdf Says:

    The photo of Stephen Wiesner reminds me of the later ones of Bobby Fischer, another genius who went into seclusion at the height of his fame. (Fischer was also unfortunately crazy, which Wiesner seems not to have been).

    I met Philip Agre a few times before his disappearance so I took notice when he went off-grid. (There was a period of alarm between when he went missing and when the police located him, so people who knew him were upset about his possible fate). The Wapo article doesn’t dishonor him or anything like that, but it seems a bit tacky of them to run it after all these years. Maybe it was a slow news day.

    Ettore Majorana, of Majorana fermions, disappeared mysteriously in 1938, and to this day nobody knows where he went or what happened to him.

    RIP, Dr. Wiesner.

  4. Scott Says:

    asdf #3: If Wiesner was crazy—and having met him, I’m not going to say with confidence that he wasn’t—then may the world be blessed with a million more who are crazy like him.

  5. Mitchell Porter Says:

    Reading this story, I wondered “what it was like” to be so far ahead of his time. It’s a bit like Feynman talking about nanomachines in 1959…

    Any lively university department will have a number of people following eccentric lines of thought. Wiesner’s eccentric ideas just happened to be the next generation’s bread and butter.

    However, in his case I have to wonder if his paper was kept out of print by the NSA. That could be a sufficient source of bitterness to make him join Grothendieck and Perelman in exile from academia.

    As for “today’s Wiesners”, well, I might be able to list two dozen names, mostly in physics, of people whose ideas *could* be awaiting recognition. The barriers to recognition can take many forms. Sometimes it’s social class; sometimes the good idea is tied to many bad ideas or to wild ambitions; sometimes the idea really does break taboos or is just too alien for understanding. Wiesner came from a very privileged position – son of an MIT president! – and as I have speculated, perhaps his problem was that his ideas had to be kept secret for reasons of national security.

    A few readers of this blog might recognize the name Ron Maimon. He went to Harvard and coauthored a few string theory papers, but dropped out I think. Much later he became notorious for contributing to various Q&A forums, scoring highly, and then getting banned on some matter of principle. He had a few ideas of his own, e.g. a theory of how to obtain nuclear fusion energies from purely chemical processes (i.e. “cold fusion”). He also kept track of people who originated various well-known ideas in physics but didn’t get credit for it. One example is Ernst Stueckelberg, who now has some degree of recognition; another, who Ron seems to have unearthed by himself, is David John Candlin, who first figured out the fermionic path integral.

    Ron also took the Wiesner-like step of moving to Israel to escape American fascism, though he only did it when Trump came along… The comparison between contemporary America and Weimar Germany has actually been made many times in fringe political writings, perhaps this was the basis of Wiesner’s 2013 forecast.

  6. Chaoyang Lu Says:

    Scott, thanks for writing this very thoughtful article. Indeed, Wiesner’s unique, remarkable, uncloneable. My only interaction with him was in the selection of Micius Quantum Prize (as the general secretary of the Foundation). Stephen Wiesner was one of the laureates of the Micius Quantum Prize 2019. Stephen was hard to reach and avoided publicity. And he certainly didn’t wish to travel out of Israel. To “establish the principle that great scientific discoveries ought to be honored even when they are made by people who shun publicity and do not fit comfortably into academic or institutional social structures”, the Foundation made an exception for him to receive the prize without traveling and attending the ceremony.

  7. Chaoyang Lu Says:

    Among the very very few email replies, Stephen once said in his email: “… space program. It is good to get people looking up rather than fighting over land and resources down here.”

  8. Scott Says:

    Mitchell Porter #5:

      However, in his case I have to wonder if his paper was kept out of print by the NSA.

    Sire I have no need of that hypothesis. 😀 (Note that neither the NSA nor anyone else did anything to stop Bennett and Brassard … and also that, for well-understood technological reasons, QKD still isn’t in significant use, and quantum money isn’t in any use at all, a half-century after Wiesner envisioned these things. So the NSA would have to have a ridiculously long time horizon!)

      A few readers of this blog might recognize the name Ron Maimon.

    I’ve interacted online with Ron Maimon, and even met him in person once at a seminar in Israel. I think that Ron’s voluminous answers on Quora and StackExchange, from the years when he was active, are some of the most interesting reading on the entire Internet (!). Agree with him or not, he can be absolutely spectacular when he writes about physics, Nietzsche, God, infinity, or thermonuclear weapons.

    Ron did, however, have strong tendencies toward anger, paranoia, unwarranted certainty, and conspiracy thinking. When he was banned from Quora, it was for not only denying a school shooting, but for directly telling the parents of one of the victims that they were liars, the blood in the photo was obviously fake, and their child never existed. Even then, the ban was only supposed to be for a short time. Ron requested that the ban be made permanent, and Quora obliged.

  9. Scott Says:

    Chaoyang #6: Thank you so much for sharing that! While writing this post, I saw on Wikipedia that Steve had recently shared the Micius Prize, and I was delighted that he’d finally received some recognition (having, e.g., been left out of the Wolf Prize). But I didn’t know the story behind it, or your involvement.

  10. Job Says:

    Steve told me that his embrace of Orthodox Judaism was, at least in part, a reaction against everything his father had stood for, including militant scientific atheism.

    Rebellion through religious obedience and conformance?

    I’ve actually seen something like this before.

  11. Artur Ekert Says:

    Thanks for writing about Steve. He was a very special man, an unsung hero of quantum information science. I liked him a lot even though I met him only once, at the 1993 Rank Prize symposium in Cotswolds (England). I asked him to give an opening talk at this, arguably the first, quantum crypto meeting, and you know what he did… just recited a poem, by William Wordsworth if memory serves me right. After that, in front of his dumbfounded audience, he stood up, walked out the door and was gone. He disappeared… and I mean *disappeared*; he left the conference hotel without a word and returned to the US. This made a big impression on me. He had this unique courage to be truly himself, not conforming to any social conventions, a bit wacky perhaps, but that’s how he was. Two years previously I had learned about his paper on the conjugate coding, and about the subsequent work by Charlie and Gilles. I remember I was both excited and disappointed. Excited, because it gave me some confidence, assurance that I was not barking up the wrong tree and my own work on quantum key distribution was not a complete nonsense (my scheme was different — the key was protected by the Bell inequality — but it was still along the same lines) and disappointed because, well, someone else had thought about it before. But then Steve showed me that it does not matter that much who did what and when. In his view when the time is ripe for an idea to pop up it will and someone will be there to articulate it. This kind of attitude made a real impact on me. Many years later, I got to know him a bit better. Our mutual friend, Aya Furuta – a brilliant Japanese journalist – visited Stephen in Israel and, for some reason or another, put us in touch. Steve phoned me up a few times, oblivious to the time difference between Israel and Singapore, and kept me awake at night, asking about the fall of communism in the 1980s in Poland and my short-lived career as an ambulance driver. Sometimes our conversations veered into science but then he was more interested in solar energy than anything quantum. And then, as abruptly as it all started it stopped. I guess his mind became  preoccupied with something else. I missed those night calls. So many times I was about to call him back but it never felt like the time was right. I was hoping to catch up with him during one of my forthcoming visits to Israel, for I also had many questions I wanted to ask him, but, sadly, Stephen is gone again, this time for good.

  12. Aartie Says:

    Thanks for sharing! I wonder what would happen if his ideas were more broadly accepted when published…

    And a question – Scott, can these photos be used for a wikipedia article about Stephen Weisner?

  13. Stephen Sarakas Says:

    Deeply moving, thank you!

  14. Scott Says:

    Aartie #12: If you give me until tonight, I’ll post a selection of additional photos and also post the credits for them, so you’ll know who to ask for permission. (Sorry, on a plane in Philadelphia about to depart for Austin, ending my first trip out of Texas since before covid!)

  15. DR Says:

    What a beautiful portrayal of an incredibly interesting human being! Thank you, and my sincere condolences.

  16. Florian Says:

    Thank you Scott for sharing your memories and insights on this remarkable man. I had the pleasure to meet his daughter Sarah a few years ago in Tel Aviv in the context of the local crypto currency community where she was engaged. When she told me her last name I jokingly asked if she was the daughter of the man who invented quantum money. I was surprised when it turned out she was indeed his daughter. I found it amazing that both turned out to work on the future of money albeit in different forms.

  17. Eilon Poem Says:

    I’m very sorry to hear Steve Wiesner had passed away.
    had the privilege to meet him personally once. It was in 2012, when I was then a postdoc in Yaron Silberberg’s group at Weizmann. Steve just phoned our office one day and said he wanted to come over and discuss an idea related to one of the group’s recent papers. We didn’t know who he was, but anyone is welcome. Then we looked his name up… When he came, we could see he was not in a good physical shape, but he was very pleasant and sat with us for almost an hour, explained his idea. We didn’t think we could do anything with it at the time, so eventually we didn’t follow up. Maybe we also didn’t completely understand him. It could may well be that we missed a revolutionary idea. We’ll never know…

  18. Scott Says:

    Artur Ekert #11: The story about Wiesner reciting a poem as his “conference talk,” then immediately leaving and flying back home, is incredible! Thanks for sharing.

  19. Stephen Wiesner | My Quantum Thoughts Says:

    […] I would like to offer my deepest condolences to his family, friends, and colleagues. To read more about him and his work, see Scott Aaronson’s blog post. […]

  20. Henry Yuen Says:

    Thanks, Scott, for these memories of Stephen Wiesner! I feel very fortunate to have crossed paths with him once, and have a small story to share. During grad school I was visiting Hebrew University and gave a talk at Dorit Aharonov’s group meeting on parallel repetition of nonlocal games. Someone was sitting in the back, who kept asking questions that were really on point. I remember feeling very pleased that someone other than Dorit and Michael Ben-Or was following my talk, but I was also rather mystified by who this person was. He looked rather disheveled, even by academic standards, with a beard very much like in Lev Vaidman’s photo in your post.

    After my talk, he came up and offered a few more thoughts (I wish I remembered what they were!). Dorit asked if I knew who he was; I didn’t, so that’s when she introduced me to Stephen Wiesner. She explained that he had been living in the desert in Israel for some time, and these days was focused on building homemade lasers. Not your dollar store laser pointer, though — like, serious wattage apparatuses that would cause real damage to your eyes if you weren’t careful. Stephen was with us the whole time, and when Dorit mentioned the lasers, he got very excited, unzipped his backpack, and pulled out a gizmo that was duct-taped together, and had a VERY large battery. Dorit (I guess trying to balance politeness against safety) gently suggested that Stephen keep that under wraps. The whole time I was thrilled to be living this experience.

    I’m very sad to hear that he’s passed, and sad that the world wasn’t more accommodating of his fiercely independent and original spirit.

  21. A. Karhukainen Says:

    Somehow I was reminded of this:

  22. Scott Says:

    Henry Yuen #20:

      I’m … sad that the world wasn’t more accommodating of his fiercely independent and original spirit.

    There’s actually an extremely interesting question here, for those of us trying to draw lessons from Wiesner’s unusual life. Yes, the scientific world should have been more receptive to quantum computing and information in the 70s and 80s: it was an oddball idea but one whose massive conceptual importance (even setting aside possible practical importance) should’ve been recognized even at the time. But Wiesner, just like Bennett, Brassard, Deutsch, and the other pioneers, had agency in how he responded to the situation. Those who knew Wiesner at the time are strongly encouraged to comment and fill in the picture, but what I’ve learned over the past couple days points toward a view of the remarkable trajectory of Wiesner’s life as, for the most part, a trajectory that he chose, not one that circumstances forced on him.

  23. Chaoyang Lu Says:

    #11 Thanks Artur for the very interesting stories. I think that “he was more interested in solar energy than anything quantum” you mentioned is quite resonant with “… rather than fighting over land and resources down here” in his email. Maybe deep in his heart, he wanted to solve the energy problem for the world.

  24. Dorit Aharonov Says:

    Dear Scott, thanks for writing these wonderful words, about the sad news of Stephen Weisner passing away, and about his truly unique and remarkable path in life. I am grateful to have had the privelage to get to know him, even if only partially – for a few years, about 2010 to 2016-7, he used to come over pretty regularly to our quantum group seminar at Hebrew U, and join us for (our very modest) lunches, modestly and openly sharing his ever-original-and-out-of-the-box thoughts and ideas about a huge variety of subjects – from sustainable energy to how to lift spaceships to the air more efficiently. I sometimes had some difficulties with his extreme and highly-non-conventional political views, but it was always interesting and eye opening to talk to him. He used to like giving short talks in our seminar about his scientific ideas. For example, he gave a lightning talk about “the learning capabilities of the quantum universe.” in 2014; I wish I had remembered what he said there! And in the same year, he wrote to me:
    “Hi Dorit,
    Interested in a talk on cheap access to space using a large (5 km) microwave antenna?
    Shabbat shalom!
    He indeed gave a short talk about this space access idea in our seminar, accompanying his explanations with many drawings on the board; Overall I wish I were more knowledgable in physics to understand his ideas more deeply. Maybe there were ideas hidden there of the magnitude of quantum money, that deserved being pushed forward for future generations. He was a fiercely truthful person, with a remarkably and inspiringly independent mind and spirit, and I felt honored that he would come visit us – it felt as if our seminar was his academic home – and maybe even a little more than just academic – for a few years. As Henry Yuen described, some of his visits at our seminar brought unexpected events with lasers and other equipment… it was always interesting to have him around. At that time, I believe he was working and living in the desert, but still was well connected and would arrive regularly. When Charlie and Gilles got the Wolf prize at 2018 for the BB84, we held a sattelite one day event at Hebrew U. (Scott, were you there? John Smolin, Eleni Diamanti and John Howell, as well as the late Yaron Silberberg, were) We very much wanted Stephen to participate in all the Wolf Prize celebrations, but I guess that got too close to his out of compfort zone, and was too much for him. He didn’t show up; he is for me a symbol of independence, truth, creativity and honesty. I am grateful to have gotten to know him; May he rest in peace.

  25. Nicholas Gruen Says:

    Hi Scott

    As one who tries to speak radical thoughts to citadels of orthodoxy — for instance government departments — I’m fascinated to know the back story behind your comment on Wiesner’s choosing his path (and to some extent choosing not to ingratiate himself with the orthodox.

    Can you say more?

  26. Scott Says:

    Nicholas Gruen #25: There’s not much backstory. I had thought that Wiesner’s now-famous Conjugate Coding paper had been rejected over and over, but Gilles Brassard explained that no, it was rejected exactly once. A different person would have simply resubmitted somewhere else, after revising to address whatever the reviewers didn’t like, wrote some more papers, etc., but Wiesner, whether because of this one rejection or not, left academia entirely and started a peripatetic life journey of which becoming an Orthodox construction laborer in Israel was only one part (more in his daughter Sarah’s update coming soon). He was the sort of person one sometimes sees at the dawn of a new field — who’s willing to consider something that sounds completely crazy (but later ends up as a huge mainstream enterprise), because he’s willing to consider all sorts of things that sound completely crazy. He did not have the usual mindset of an academic scientist, so quite possibly he really was happier choosing the path he chose.

  27. Gui-Lu Long Says:

    Dear Scott,

    Thanks for writing this wonderful article, about the sad news of Stephen Wiesner passing away, and about his truly unique and remarkable path in life. I am fortunate to have met him in person in 2017 in Jerusalem in a joint workshop to celebrate the tenth anniversary of the cooperation between NSFC and NSF of Israel.

    I heard from Charlie Bennett that Stephen has moved to Israel before, so I asked Nadav Katz, co-organizer of the workshop, to meet Stephen. Surprisingly, Nadav did not reply my request in our emails before the start of the workshop. I thought he had forgot all about it after the first day’s program. However, in the workshop banquet, Nadav told me he would give me a surprise and the surprise was to meet Stephen! Stephen, Lev Vaidman and I sat in the same table and talked a lot that evening. I forgot to ask him when he moved to Israel. What I remembered is that he told me his daughter is doing BITCOIN (I can feel that he is proud of his daughter). Of course, I told him quantum secure direct communication I and my student Xiaoshu invented in 2000 (Bennett and Brassard designed a protocol in 1982 before BB84, but was published in 2014) . He attended the program in the next-day. Later, I and Radel Ben-AV had cooperated in studying quantum synchronization, and Radel told me that he had discussed the subject with Stephen at that time and gave his opinions on the protocol he proposed.

    From your article and others’ recounts, I gradually get a picture of Steve. Born in a noble family, he is a rebellious youth of the 1960s. His rebellion is to the opposite of Hippy, going to orthodox, and going to Israel, and doing laborious work. He lived an orthodox life, and enjoying studying various subjects of science and technology.

    He is somewhat like an hermit in Zhongnan mountain in modern China, having a simple life in remote area to avoid the crowds of mundane society. But in many other aspects, like a classic Confucian, having a moral life with high standards. Perhaps, it is just the Orthodox Judaism, which has no correspondence in the Chinese culture.

    He is not keen on getting awards and prizes. As Artur’s comment “But then Steve showed me that it does not matter that much who did what and when. In his view when the time is ripe for an idea to pop up it will and someone will be there to articulate it. “. On the other hand, recognition is not at all irrelevant. For instance, from the comment of Dorit Aharonov :”When Charlie and Gilles got the Wolf prize at 2018 for the BB84, we held a sattelite one day event at Hebrew U. We very much wanted Stephen to participate in all the Wolf Prize celebrations, but I guess that got too close to his out of compfort zone, and was too much for him.”

    It was a pity that he was not given the Wolf prize (your reply to Chaoyang: having, e.g., been left out of the Wolf Prize). I am very curious why he was not awarded this prize (the maximum number of laureate is 3), taking into account of his other contributions such as quantum dense coding, in addition to conjugate coding.

    At this point, I personally think, two other pioneers should have been recognized more in quantum information processing fields. One is Paul Benioff, who proposed quantum Turing machine in 1980, where products of unitaries are used to drive the initial state of quantum computer to the final state (I proposed the linear combination of unitaries in 2002, and published in 2005). The other is Lov Grover, who invented the famous quantum search algorithm, which are the two most famous quantum algorithms together with Shor algorithm.

    I am glad Stephen was awarded the Mincius prize (see Chaoyang: Stephen Wiesner was one of the laureates of the Mincius Quantum Prize 2019) .

    May Steve rest in peace.

  28. צבי קופר Says:

    I would like to shed a bit of light on Steve’s latter years in Tekoa, Israel. He lived a fervent Zionist life. He continued exploring and continued his research here–but in slightly different fields. That research often started in hikes throughout Israel but especially directly from his house which sits 4 blocks out from the Judean desert. He told me about some of the ideas he was pursuing. For example, he was looking for ways to transform the desert, restoring it to fertility after the drain of centuries of nomadic over-grazing and of wanton destruction by Ottoman military engineers who cut ever last tree (in many areas) for railroad ties and fuel for their railroad. In one experiment, he measured and calculated the square-area required for catching sufficient dew to be channeled to a seedling. He envisioned temporary fields of plastic sheeting bringing water to tree seedlings that, when grown, would fix the earth, provide shade for a diversifying ecosystem that could sustain itself–perhaps transforming clouds and rain as well by lowering ground reflection. Although these ideas are less novel than his breakthroughs in Physics, he was unique in his pursuit and advocacy for small steps to transform the environment of the land he loved. He explored geology, recognizing that there were fields of rocks containing (admittedly) low-yields of energy. He happened to be passing my home lot as I was laying foundations. I showed him the trench-like excavated space left after building the walls to my basement and asked (naively) if he had an idea for tapping geo-thermal energy. He said “err, no—that wouldn’t be enough volume but you might be able to use that area to create heat (and cold) storage.” His idea was to drop an input duct into these pockets next to the basement walls—an input duct far from the house and an output duct into the house and then fill the pocket with grapefruit size rocks, covered by a cheap concrete roof. Then, I’d draw the summer air through these rocks and into the house, cooling the rocks at night due to an on-average 10 degree C temperature gradient between night and day, and then cooling the house during the day. He came back the next day with a 3 or 4 pages of equations handwritten on notebook paper that calculated the desired volume of rock cavity needed to cool the home. I did the engineering and got the thing working (two separate systems with slightly different configurations for the first and second floors) with fabulous results. Not earth-shaking but quite a nice idea. His calculations worked out to be quite indicative of my real-world results.
    I’m still searching for a picture of Steve, me and another old man (all with white beards) putting a new roof on our synagogue. He paid his dues through work. He put in a water heater (conventional), helped with some wiring and altering an electrical device (a swamp cooler) for use during the Jewish Sabbath.
    As an anecdote, I asked Elisha Svetitsky, a Physics Post-doc from the Hebrew University in Jerusalem, to give a lecture in my home. He chose to speak about the history of breakthroughs in Physics and the biographies of some of the people responsible. I invited Steve to attend and told Elisha that Steve might attend. Steve said he’d prefer a session learning Talmud but came anyway. It was extremely satisfying when Elisha introduced Quantum Information Science that he started by saying that it is awe-inspiring that one of the seminal figures in the field and essentially it’s father was sitting in the parlor with us.

  29. Scott Says:

    צבי קופר #28: Thank you so much for sharing those stories, which filled a real gap in this post! When talking to Steve, I sometimes wondered: “How could the inventor of quantum money not have considered the most basic theoretical questions about quantum money?” It appears the answer is: because he was too busy considering geothermal energy, tree seedlings, locating the Third Temple in outer space, and a thousand other ideas and projects that caught his fancy.

  30. Izzy Kalman Says:

    My wife, Miriam, and I had the great pleasure to befriend Steve Weisner shortly after meeting him in 2015 at minyan Carlebach, shortly after we moved to Tekoa, where we lived for the subsequent six years.

    We had him over for many Shabbat meals, and we loved his company. He had endless tales to tell, tales that might seem made up, but we knew that they were real. Fortunately, we had been informed early on by Tzvi Cooper, who is largely responsible for running the Carlebach shut, that he was a genius.

    He was fiercely independent and didn’t like being helped, something we were inclined to do because he obviously was no longer in the best of health.

    I have a three-dimensional wood-and-rope puzzle that I had received years ago as a gift. Though the solution must be something simple, it seems logically impossible. I had spent hours trying to solve it, to no avail. Many of my guests also fruitlessly attempted to solve it.

    I showed it to Steve. He gave it a go, and within several minutes had it solved!

    Unfortunately, after a while he distanced himself to us. My wife and I are involved with grassroots peace groups in Israel, and because of my great interest in his life, he became suspicious that I was a spy supported by left-wing NGOs, and would no longer visit.

    Fortunately, when I ran into him again at a later time, he had lost his hostility and I was grateful that he treated me like a friend.

    His passing is a great loss to humanity and to the Jewish people, and may his soul, that had known much suffering in this world, find the bliss he deserves in Heaven.

  31. Arul Says:

    Some 80 year olds lift weights but some are fragile. There should be computational evidence gathered on the dna to explain the dichotomy. Yitang Zhang got his place in his 50s.

  32. Carsten Says:

    Actually, Stephen inadvertently also invented one of the central elements of modern cryptography, namely Oblivious transfer ( He did not see this himself at the time, though, which is why Oblivious transfer today is mostly attributed to Michael O. Rabin.

  33. Virginia Freedman Says:

    Thank you for your blog. I am a distant cousin of Stephen Wiesner and was very sad to hear of his passing, having fallen out of touch with him because he no longer used his email. I remember having one of the most densest conversations of my life, walking among the strang mixture of the ancient of Abraham’s wells and the modern that is Israel. Was in my late 20’s and feeling a little lost and remember him for his kindness in sensing this and being being encouraging and his avuncular nature.

  34. Daniel Simkovitz Says:

    I met Steve Wiesner at Harvard Hillel shortly after I arrived in Boston from Detroit in 1983. Steve was an interesting, seemingly off-beat character from the sixties doing this own thing with science. He described working on his own experiments with amorphous silicon for solar energy collection. Steve met his wife Beverly around the same time I met my wifeJuliette. Steve married and moved across the Charles River to Brookline around the same time as us. Steve and Beverly had their daughter Sarah around the same time as Juliette and I had our daughter Abby. We went to the same schule. One evening around 1986, Beverly and Steve invited us for Hanukah dinner and candle lighting. . There was one other guest, Jerome Wiesner, simply introduced to us as Steve’s father. What a contrasting father and son image – Jerome dignified, professorial and formal; Steve, the quasi hippie refugee from the 60s. Steve’s father told us about visits with Ben Gurion in the 1950s. Juliette and I did not know who Jerome Wiesner was. Was he a Manhattan Project scientist? Steve did not tell us and we did not ask. Think of the conversation we could have enjoyed had we known that Steve’s father was the President of MIT and science advisor to JFK. In April 1989, I turned to the Science and Technology section of the Economist magazine to read about the recent sensational claim of cold fusion at the University of Utah. The first article opened describing the work of a graduate student at Columbia University in the 1970s named Stephen Wiesner, presently at Thinking Machines in Cambridge MA. Steve ? What did Steve have to do with innovating cold fusion? I read on, the article was not about cold fusion, but went on to reveal steve’s pioneering ideas about quantum encryption, ahead of its time in the 1970s and now understood for its importance. This is how I learned about steve Wiesner’s foundational paper as the father of quantum encryption. Wow.

    Steve called me one day and invited me to see his latest creation, the world’s simplest and cheapest solar still. We descended to the basement storage compartment of his condominium, a space he had converted to a small science workshop. There it was, constructed from cleaning hangers, tissue paper, and a plastic garbage bag. He poured me a glass of drinking water that he said he had distilled from salt water taken from Boston’s famously polluted harbor. I was too terrified to drink – one of my regrets in life. Think of the story I could now tell my grandchildren – drinking fresh H2O extracted from Boston’s filthy Harbor.

    We saw Steve on our visits to Israel. We visited Steve and Beverly when they were living in Mitzpe Rimon in the Negev Desert and steve was working at the science research center at Sde Boker. Steve eventually retired to Jerusalem. He continued to work on unique ideas and he told us that he had setup a work lab in a small space in Mea Shearim, Jerusalem’s oldest Haredi neighborhood. This we had to see. Sure enough, Steve had rented a shed, no larger than a one car garage, among Meah Shearim’s crowded apartments, stores, and Yeshivas where he had indeed setup his personal work lab. We last saw Steve in Tekoa, a community where I also have family. Though Steve appeared frail, our conversation remained stimulating, memorable, and warm. We miss Steve, a truly unique, interesting, kind individual and free spirit.

    Thank you for creating your blog.

    Daniel Simkovitz, Brookline MA

  35. David Lynch Says:

    A while ago, maybe seventy years now, my family lived down the street from the Weisners. I remember Steve precisely, the way a child does, as a voice and a laugh and a gesture (the one he’s making in the photo) and endless ex tempore stories about some character he made up named Pecky Penguin told out in a hammock in the summer. My only technical reminiscence is the little tic-tac-toe player he wired up (relays, not transistors, thank you very much) we played with in the pantry of the big old white mansion the Weisners lived in.

    I was an MIT faculty brat too, our mothers were close, and in time, long after Steve had disappeared from their lives (he was working on solar cells in Israel, I knew that) I took my own daughter to swim in the pool Jerry had built for Laya. May they all rest in peace.

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