The Quantum Hype Bubble Is About To Burst

The Quantum Hype Bubble Is About To Burst

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Quantum technology current attracts a lot  of attention and money, which might explain   why they’re missing on my end. But it’s not just  governments who think quantum everything is where   your taxes should go, business investors and  companies are willing to putting in big money,   too. This has had a dramatic impact on quantum  physics research in the past decade. It’s also   created a lot of hype, especially around quantum  computing. But if so much of quantum computing   is hype then why are companies like Google and IBM  pouring so much money into it, what’ll happen when   the investment bubble bursts, what’s the “quantum  winter”, and what does it mean for all of us?   That’s what we’ll talk about today. There are   several different quantum technologies, and as  a rule of thumb, the fewer headlines they make,   the more promising they are. Take for  example, quantum metrology. That’s not a  

mispronunciation of meteorology, that’s making  better measurements with quantum effects. You   basically never read anything about this. But  it’s really promising and already being used by   scientists to improve their own experiments. You  can learn more about this in my earlier video.  On the other hand, you have those quantum things  that you read a lot about but that no one needs or   wants, like the quantum internet. And then there  is quantum computing which according to countless  

headlines is going to revolutionize the world.  Quantum computers are promising technology, yes,   but the same can be said about nuclear  fusion and look how that worked out. A lot of physicists, me included, have  warned that quantum computing is being   oversold. It’s not going to change the world,  it’ll have some niche applications at best,   and it’s going to take much longer than  many start-ups want you to believe.  Though I admire the optimism of the quantum  computing believers and also the vocabulary.   For example, there’s a startup called  “multiverse” that is “Working with   customers in more than 10 verticals”. Some of  them don’t find the way back from the bathroom. 

Or here’s one called “universal quantum” which  has a “fault tolerant team” that “embraces   entanglement” and helps everyone find a “super  position”. If you look at them, do they collapse? This company also recently  published a blogpost titled   “Six reasons Liz Truss needs a quantum  computer” which explains for example,   “Quantum computers are suited to modelling  complex systems, making them better at   forecasting both near-term weather patterns  and the long-term effects of climate change.” Last time I looked, no one had any idea how to  do a weather forecast on a quantum computer.   It’s not just that no one has done it,  no one knows if it’s even possible,   because weather is a non-linear system  whereas quantum mechanics is a linear theory. Here is an example of some recent quantum hype,   from a website called “Investors Chronicle”  in an article titled “Quantum computing:   a new industrial revolution”. After creating a  lot of fog about superpositions and interference,  

they explain that quantum computers are  close to showing “quantum advantage” and   that “Quantum advantage, therefore, can be  interpreted as being when problem-solving   power can be applied to real world issues, which  makes it much more interesting for investors.” That’s just wrong. Quantum advantage has indeed  been demonstrated for some quantum computers   but that just means the quantum computer did  something faster than a conventional computer,   not that this was of any use for real world  issues. They just produced a random distribution   that would take a really long time to calculate by  any other means. It’s like this this guy stapling  

5 M&M. That’s a world record, hurray,  but what are you going to do with it? Problem is, a lot of CEOs in industry and the  financial sector can’t tell a bra from a ket and   believe that quantum computing is actually  going to be relevant for their business,   and that it’s going to be relevant soon.  For example, at a recent Quantum Computing   conference in London, the managing director of  research at Bank of America said that quantum   computing will be “bigger than fire”.  The only way in I can see this coming   true is that it’ll produce more carbon emissions. This bubble of inflated promises will eventually   burst. It’s just a matter of time. This’ll cause  a sudden decline of investment in quantum tech  

overall and be the start of a difficult time  for research and development. This scenario has   been dubbed the “quantum winter”. And winter is  coming. But before we get to the quantum winter,   let me briefly summarize how quantum  computers work and what their problems are. A conventional computer works with bits that  take on one of two discrete values. A quantum   computer instead uses qubits that can be in  arbitrary *superpositions of two states. A  

quantum computer then works by entangling the  qubits and shifting this entanglement around.   Entanglement is a type of correlation,  but it has no analogy in conventional   computers. This is why quantum computers can  do things that standard computers can’t do.  For some mathematical problems, a quantum  computer can give you an answer much faster   than any conventional computer possibly could.  This is called “quantum advantage”. Those  

problems include things like factorizing large  numbers into prime factors. But also calculating   properties of molecules and materials without  having to chemically synthesize them first.   Putting these questions on a quantum  computer could speed up material design   and drug discovery. Quantum computers can also  solve certain logistic problems or optimize  

financial systems. This is why, if you’re Bank  of America, you think it's bigger than fire. And like fire, quantum computing is not magic,  it’s an application of standard quantum mechanics.   There is no speculative new physics involved.  It’s rather to the contrary. Claims that quantum   computers will *not work rest on speculative  new physics. But it’s one thing to say if  

you could build them, they’d be useful. It’s  another thing entirely to actually build them.  So what does it take to build a quantum computer?  First of all you need qubits. Then you have to   find a way of entangling many of those qubits.  And, like a conventional computer, a quantum   computer needs an algorithm, that tells it how  to move the entanglement around. Eventually,   you make a measurement which collapses the  wave-function and you read out the final state.   This final state should be one that answers your  question correctly with high probability. This  

means most importantly, a quantum computer isn’t  a stand-alone device, it needs other devices for   the programming and the readout. The quantum part  is really just a small piece of the whole thing.  Now let’s talk about the problems. First there’s  the qubits. Producing them is not the problem,   indeed there are many different ways  to produce qubits. I went through   the advantages and disadvantages of  each approach in an earlier video,   so check this out if you want to know more. But  a general problem with qubits is decoherence,   which means they lose their  quantum properties quickly. 

The currently most widely developed  systems are superconducting qubits and   ion traps. Superconducting qbits are used for  example by IBM and Google. For them to work,   they have to be cooled to 10-20 milli Kelvin,  that’s colder than outer space. Even so,   they decoherence within 10s of micro-seconds. Ion traps are used for example by IonQ and   Honeywell. They must “only” be cooled to a  few Kelvin above absolute zero. They have much  

longer coherence times, up to some minutes, but  they’re also much slower to react to operations,   so it’s not a priori clear which approach is  better. I’d say they’re both equally bad. The   cooling isn’t only expensive and energy-intensive,  it requires a lot of equipment and it’s difficult   to scale to larger quantum computers. It seems  that IBM is trying to do it by breaking world   records in building large cryogenic containers.  I guess if the thing with quantum computing   doesn’t work out, they can rent them out  for people to have their heads frozen. There are some qubits that operate at  room temperature, the most promising   ones of those are currently nitrogen vacancy  systems and photonics on a chip. However,   for both of those, no working quantum  computer exists to date and it’s unclear   even what the challenges may be,  let alone how to overcome them.

The next biggest problem is combining these  qubits. Again, the issue is that quantum   effects are fragile, so the quantum computer is  extremely sensitive to noise. The noise brings in   errors. You can correct for those to some extent,  but this error correction requires more qubits.  More qubits bring problems by themselves, for  example, they tend to be not as independent   as they should be, an issue known  as “crosstalk”. It’s kind of like   if you’re trying to write while moving your  feet in circles. It gets really difficult.   The qubits states are also drifting if you leave  them unattended. Indeed it’s somewhat of a mystery  

at the moment what a quantum computer does if  you don’t calculate with it. It’s like it’s   difficult to calculate what a big quantum system  does. Maybe we can put it on a quantum computer? And finally there’s the issue of the algorithms:  Few algorithms for quantum computers are known,   an issue that goes often unmentioned because  everyone is focused on the technology. Wikipedia  

helpfully has a list of quantum algorithms.  It’s short. Several of those algorithms don’t   compute anything of practical use, and for some  it's not known if they lead to any speedup.  As this brief summary makes clear, the challenges  are enormous. But how far along is the technology?   The largest current quantum computers have  somewhere between 50 and 100 qubits, though   IBM has a roadmap saying they want to make it to  a thousand next year. Two different approaches   have demonstrated a “quantum advantage”, that  is, they have performed a calculation faster   than the currently fastest conventional computer  could have done. However in those demonstrations   of quantum advantage, the devices were executing  algorithms that did not calculate anything of use. 

The record breaking “useful” calculation  for quantum computers is the prime-number   factorization of 21. That’s the number, not the  number of digits. Yes, the answer is 3 times 7,   but if you do it on a quantum computer you can  publish it in Nature. In case you are impressed   by this achievement, please allow me to clarify  that doing this calculation with the standard   algorithm and error correction is way beyond  the capacity of current quantum computers.   They actually used a simplified algorithm  that works for this number in particular.

To be fair, there have been some cute  applications of quantum algorithms for   simple examples in quantum chemistry and machine  learning, but none of this is anywhere even close   to being commercially interesting. How many qubits do you need for a   quantum computer to do something commercially  interesting? Current estimates say it’s several   hundred thousand to a few millions qubits,  depending on what you want to calculate and   how large your tolerance for errors is. A lot of quantum computing enthusiasts   claim that we’ll get there quickly  because of Moore’s law. Unfortunately,   I have to inform you that Moore’s law isn’t  a law of nature. It worked for conventional   computers because those could be miniaturized.  However, you can’t miniaturize ions or the   Compton wavelength of electrons. They’re already  as small as it gets. Nature’s a bitch sometimes. 

In the past years there’s been some noise around  Noisy intermediate scale quantum computers, or   NISQs for short. Those are small quantum computers  in which you just accept the noise, kind of like   YouTube comment sections. But no one seems to have  found anything useful to do with them and the hype   around them has noticeably died down recently. I guess you understand now why I am extremely   skeptical that we are anywhere  close to commercially relevant   applications of quantum computers. But  let’s hear what some other people say. There is for example Mikhail Dyakonov,  a physics prof who has worked on quantum   things much longer than I have. He’s  written a book that was published in   2020 under the title “Will We  Ever Have a Quantum Computer?”   It has only 49 pages which is what happens  if you agree to write a book but then notice   half through you’d rather do something else.  He finishes by answering his own question:

“No, we will never have a quantum computer.  Instead, we might have some special-task (and   outrageously expensive) quantum devices  operating at millikelvin temperatures.   The saga of quantum computing is waiting  for a profound sociological analysis,   and some lessons for the future should be  learnt from this fascinating adventure.” The brevity of Dyakonov’s book is balanced  by another book “Law and Policy for the   Quantum Age” by Chris Hoofnagle and Simson  Garfinkle, who make it to a whooping 602 pages.   Their book was just published earlier  this year, it’s freely available online,   and it has an adorable cat pic on the cover,  so definitely go check it out. Hoofnagle is   a professor for law and Garfinkle is a data  scientist, but their book has been heavily   informed by people who work in quantum computing.  They look at the possible future scenarios. The  

most likely scenario, they say, is the “Quantum  Winter” which they describe as follows: “In this scenario (call it “Quantum Winter”),  quantum computing devices remain noisy and   never scale to a meaningful quantum advantage…  After a tremendous amount of public and private   monies are spent pursuing quantum technologies,  businesses in the field are limited to research   applications or simply fail, and career paths  wither. If that happens, funding eventually   dries up for quantum computing. Academics and  scientists in the field either retool and shift,   or simply appear irrelevant, even embarrassing.” Then there is Victor Galitski, Professor at the   Joint Quantum Institute at the University of  Maryland who wrote in a 2021 post on LinkedIn:  “The number of known quantum algorithms, which  promise advantage over classical computation,   is just a few (and none of them will "solve  global warming" for sure). More importantly,   exactly zero such algorithms have been  demonstrated in practice so far and   the gap between what’s needed to realize them  and the currently available hardware is huge,   and it's not just a question of  numbers. There are qualitative   challenges with scaling up, which will  likely take decades to resolve (if ever).”

Most recently, there was an opinion piece  by Nikita Gourianov in the Financial Times.   Nikita works on computational quantum physics  at the University of Oxford. He writes “As   more money flowed [into quantum computing],  the field grew, and it became progressively   more tempting for scientists to oversell  their results… After a few years of this,   a highly exaggerated perspective on the promise  of quantum computing reached the mainstream,   leading to… the formation of a classical bubble.” He then points out that no quantum computing  company is currently making profit and   that “The little revenue they generate  mostly comes from consulting missions   aimed at teaching other companies about “how  quantum computers will help their business”.” I have to disagree on the final point because  big companies have another way to make money   from quantum computers, namely by renting them  out to universities. And since governments are   pouring money into research, that’s quite a  promising way to funnel tax money into your   business. Imagine the LHC was owned by Google  and particle physicists had to pay to use it. 

That’s how I think it’ll go with quantum  computing: First all the smaller startups   will falter because they don’t reach their  milestones, venture capital will evaporate,   and all the overeducated quantum computists  in academia will use grant money to pay   a few large companies who own the only  workable devices. And while those devices   are interesting research objects, they’ll  not be useful for commercial applications.  I might be totally wrong of course. Maybe one  of those start-ups will actually come up with   a scalable quantum computing platform. I don’t  know, I’m guessing as much as everyone else.  But if quantum winter is coming, what does it mean  for you and me? Well, some people will lose a lot   of money but that just means they had too much  of it to begin with, so can’t say it bothers me   all that much. There’ll also be fewer headlines  about how quantum computing is supposedly going   to revolutionize something or other, which I’d  say is a good development. And we’ll see many  

people who worked in quantum computing going into  other professions. Chances are in ten years you   can have a nice chat about the finer details of  multi-particle entanglement with your taxi driver.   I don’t know about you, but I’m  looking forward to quantum winter.

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2022-11-06 11:31

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