Quantum computers would be a new kind of computer. Rather than using transistors as their basic building blocks, they use quantum stuff. This would let us solve certain problems much faster, including important problems for science and maths. You can find some explanations here and here. We are scientists working on the theory of how these computers can be kept error free. We are participants at the conference on Fault-Tolerant Quantum Technologies currently being held in Spain. Ask us anything about quantum, science, becoming a scientist, etc.

Proof on conference website.

Here's some info on a few of our participants, though some of the rest will contribute too.

Dr James Wootton I work at the University of Basel, mostly on topological quantum computation. This will use particles called anyons that don't actually exist in real life. But we have ways to tease them into existence.

The most interesting thing about me is my project that lets you take part in our research. See the subreddit for more details: /r/decodoku.

I did a talk at the conference last week. Here is the bit where I tell everyone that Redditors are currently better at quantum error correction than scientists.

Dr. Steven Flammia

I’m an Associate Professor at the University of Sydney where I research quantum computation. My interests are quite varied, but mostly focus on how to find and fix the bugs in quantum computers. This is hard to do since we cannot naively “look inside” or we risk collapsing the delicate quantum superpositions that power the computation. Clever researchers have nonetheless figured out ways to do this so-called quantum error correction, and finding the best and most practical methods for it is a major theme of my research.

Dr Dan Browne

I am a researcher and academic at University College London, where I work on the theory of quantum computers and run a PhD programme on quantum technologies. Many of the strange features of quantum mechanics have been known for almost a hundred years, the aim of quantum technologies is to exploit these for new and improved kinds of computation, cryptography, sensing and imaging. Quantum effects tend to be very fragile, which is one reason we don’t see them at human scales. Here in Benasque in the Spanish Pyrenees, we are holding a small conference on fault-tolerant quantum technologies for international researchers collaborating to develop ways to make these fragile effects robust enough to be useful.

Dr. Ben Criger

I'm a researcher at the RWTH in Aachen, Germany and the TU Delft in the Netherlands, where I work on modifications to quantum fault-tolerance which makes it easier to implement in hardware, and modifications to the hardware that make it easier to implement quantum fault-tolerance. If you want to take a look at the nitty-gritty details of what I do, you can find most of it at github.com/bcriger.

Dr. Michael Kastoryano

I am a researcher at the Niels Bohr Institute in Copenhagen, Denmark. I work mostly work on problem at having to do with finding clever ways of storing and manipulating quantum information, as well as formulating and explaining exotic physical systems using the laws of information theory.

Dr Earl. Campbell

I first got interested in quantum physics because it is more bizarre than anything else humanity has ever conceived (https://www.epsrc.ac.uk/about/people/earl-campbell/). By good fortune it also has useful practical applications like quantum computation! Now I work as a research fellow at Sheffield University (https://earltcampbell.com/) designing noise-tolerant quantum computers.

Dr Mercedes Gimeno-Segovia

I am a researcher at the University of Bristol and University of Calgary, and I spend my days thinking about how to build a large scale linear optical quantum computer. I've always loved science, but quantum computing has interested me since I first encountered quantum physics. After talking to some experimentalists I became fascinated by the prospects of large-scale linear optical quantum computing, and I begged my PhD supervisors to let me do my PhD project on it. I haven't looked back! I also write a blog on quantum computing and related subjects : www.quantaforbreakfast.wordpress.com

Dr. Ben Brown

I work at the University of Copenhagen on quantum error correction. Quantum error correction is necessary if we are ever to design a quantum computer that is robust to faults. I design and test different quantum error-correcting codes to look for the best and cheapest architecture for a quantum computer. I recently published an open source paper with very colourful figures that you can view here http://www.nature.com/ncomms/2016/160729/ncomms12302/full/ncomms12302.html (Note: This Ben didn't actually get round to answering any questions.)

Comments: 177 • Responses: 67  • Date: 

YaZko13 karma

Hi guys, (classical) computer scientist here. I have a bit more programming language oriented question if you do not mind, I hope it makes some sense.

Considering the history of computer science, two major things evolved in parallel: hardware, and theoretical models for calculus. The study of the latter would lead notably in particular to the development of various programming languages once both branches have been mature enough.

Now in the context of quantic computer science, we hear on quite a regular basis about impressive progress on the hardware side. However on the calculus side, I am still only aware of the very "physics oriented" calculus over Hibert spaces. Would you know if alternative models have been developped, potentially sketching ideas for high level programming languages over quantic architectures?

Thanks for the AMA!

FTQC_researchers6 karma

There have been a number of proposals for alternative mathematical models of quantum physics or computing and also high level programming languages.

Here is a link to one of these based on the mathematics of category theory but expressed using diagrams.

https://en.m.wikipedia.org/wiki/Categorical_quantum_mechanics

Here is an article on quantum programming languages:

https://en.m.wikipedia.org/wiki/Quantum_programming

Dan

FTQC_researchers6 karma

Although we don't fully understand the question, I have the feeling that you are asking whether there is a natural way to program quantum algorithms.

Right now we have a few subroutines that we use frequently in various quantum algorithms, but that's it. We don't really have a good way to understand quantum algorithms intuitively, so we don't know how to make an intuitive high level quantum programming language. Otherwise we are mostly concerned about how to compile known high-level quantum algorithms into a sequence of gates that we can apply to concrete (quantum) physical systems.

Xiaotong Ni

FTQC_researchers1 karma

I did an AMA a month ago and gave this answer to a question. Perhaps it is also relevant for you.

James

puzzlewhisperer7 karma

What are some examples of ways quantum computing could be used to improve things we do during everyday life?

FTQC_researchers14 karma

First of all, it is very difficult to predict what a machine can do that we have not yet built. The revolution from quantum computing will surly not be as overwhelming as the revolution we have experienced with classical computers, simply because our societies are already accustomed to the principle of computing.

As of now, it seems likely that a quantum computer will be most useful as a research tool. You can compare it to the impact of a scanning tunneling microscope, which very few individuals have in their homes but has been invaluable to biology and chemistry research, which in turn has led to tremendous progress in medicine and materials.

That being said, we do expect quantum information technologies to revolutionize the field of cryptography, the manipulation of complex molecules and materials science in general. One particular example is the process of carbon capture, which is an intractable problem in physical chemistry, but might be tractable with the help of quantum computing. This could be critical in curbing the effect of global warming.

Finally, today's most powerful supercomputers have roughly the same number of transistors as the human brain has neurons. However, they consume a quadrillion (1'000'000'000'000'000) times more energy then the human brain. The technology involved in developing quantum technologies could help us bridge this energy gap, and make computing ultra cheap in terms of energy.

Michael

FTQC_researchers11 karma

A very nice analogy I once read in a paper, is that quantum computers are going to be a similar revolution to classical computers, as laser light was to lightbulbs. It didn't replace them, but it opened the possibility to a huge number of applications that hadn't even been imagined before.

Mercedes

MarsBars4Lyfe6 karma

What advice do you have for a young person wanting to go into science (physics, specifically)?

FTQC_researchers9 karma

A lot of research has shown that your peer group (people around you, e.g. in your classroom) is one of the biggest factors in how well you learn. Just google "peer group effect". The optimal for any student is to be surrounded by peers who are slightly more knowledgeable, and who happy to have intelligent debate. In short, having smart friends is more important than having smart teachers.

Also, the best scientists are those who do it for the pure joy of it!

On the basis of this I'd suggest the following approach: Find smart friends also interested in science and nerd out together. Find fun in talking about science and the rest will fall into place.

That and maths. Learn maths. Doesn't matter what science you do, maths will help.

Earl

MarsBars4Lyfe3 karma

Thank you so much, Dr. Earl! I'm really, really passionate about this and I aspire to be a physicist like you. You are the people shaping and changing our understanding of the world, and I admire all scientists so very much. Thank you!

FTQC_researchers2 karma

You are welcome. Never stop aspiring :)

FTQC_researchers5 karma

A degree in physics is a good place to start. Beyond that, you will start to form a better idea yourself what area you want to go into.

James

FTQC_researchers4 karma

Bare in mind that your choice of masters project is the most important decision in your career. It largely determines your future career path Michael

Sealatron3 karma

Oh God I hope this isn't true. My Masters project was a complete farce and I'd be embarrassed to show it to anyone. Even worse, it's in a field I'd still like to get into, so people are going to want to read it if I pursue that. Disaster.

Please someone tell me it's common to completely distance yourself from undergraduate/Masters work!

FTQC_researchers4 karma

You can still make it. We all have crap in our back catalogue. Learning from it is probably the most important thing, good or bad.

James

FTQC_researchers2 karma

Have you thought about summer internships/projects in academic departments? As an undergrad, I knew I wanted to do research but didn't know in what area so I did about four different projects before settling on quantum computing. It is a great opportunity to show your interest and skills and becomes very valuable when applying for graduate programs. You also get to learn a lot about the research area and techniques. Don't give up!

Mercedes

LawOfExcludedMiddle2 karma

What did you do your undergrad in?

FTQC_researchers1 karma

I think all of us did their undergrad in physics. But we've got computer scientists here at the conference too. Maybe even a mathematician!

James

Leto__II6 karma

Does this have the kind of computing power to operate a proper molecular level 3d printer so we can finally stop screwing around and have a Star Trek-esque replicator? "tea - earl grey - hot"...dope

FTQC_researchers4 karma

Quantum physics actually shows that a replicator is impossible! It is a result called the no-cloning theorem. If you first get you head around Heisenberg's uncertainty principle, then no-cloning is easy to understand.

So Heisenberg's uncertainty principle says you can't know the position and momentum of a particle. You can learn the position or the momentum, but not both at the same time.

Assume you we able to clone or replicate on the molecular level. Measure position for one of the copies and momentum for the other copy. You've learnt both the position and momentum. But this violates Heisenberg. Therefore, the quantum replicator is an impossible technology.

Earl

QuiteSomeBiscuit8 karma

So Heisenberg's uncertainty principle says you can't know the position and momentum of a particle.

Ah, ah, ahhh, but the Enterprise has Heisenberg (uncertainty) compensators.

FTQC_researchers6 karma

But there is that episode where the transporter breaks down so Rikker gets cloned! Which is impossible. Unless the two Rikkers are not perfect quantum clones and only classical clones.

Earl

FTQC_researchers4 karma

They are only useful in the teleporters. Teleportation isn't physically impossible, just practically impossible, and the Heisenberg compensators sort that out.

Exact replication is cloning, which is against the laws of physics, and so cannot be dealt with through Heisenberg compensation.

James

bazutti3 karma

Hmm...so that's a solid "no" on the replicators? I'm not gonna lie, this might be the most bummer thing I've heard this month.

FTQC_researchers9 karma

Exact replication at the molecular level is a solid "no". But that won't be required for making Picard's tea.

James

FTQC_researchers5 karma

Well you couldn't replicate all the way down to the quantum level. You could build an approximate replicator that doesn't make a perfect copy and by eye you couldn't see the difference. So maybe that will cheer you up a bit. But I think it is fun to think about why replication is impossible in the quantum realm.

Earl

FTQC_researchers2 karma

Does this have the kind of computing power to operate a proper molecular level 3d printer so we can finally stop screwing around and have a Star Trek-esque replicator? "tea - earl grey - hot"...dope

I don't think we are the ones that will invent the replicator. But maybe some of the quantum computer's power at problems like protein folding will be of help. Until then, we'll have to make do with tea bags.

James

Xerus_3 karma

Would the security really improve or a quantum computer would ne able to force another 'quantic password' the same way a computer can 'bruteforce' a password today ?

Could new protocols/technologies regarding cyber security be created, making internet navigation completely safe for instance ?

FTQC_researchers5 karma

The idea of quantum key distribution (QKD) is one way in which quantum systems provide enhanced security over standard (classical) systems. QKD has certain models of security where it is provably secure, but this is only a model. In the real world, the weakness in a cryptosystem is not whether the encryption is classical or quantum, but rather how it is implemented. So while quantum devices do offer some prospects for enhanced security, one should take these claims of perfect security with a grain of salt.

On the flip side, a quantum computer can indeed break the widely used RSA cryptosystem, but we are still very far from being able to implement these algorithms. So your internet transactions are most likely safe for the foreseeable future. It is a current topic of research to design classical cryptosystems that can resist a quantum attack, and there are several candidates, but nothing is yet conclusive.

Steve

zeroReiZero2 karma

What about the claims that quantum computing will break the entire cyber security and encryption system currently being used worldwide?

Another topic I'm interested is about the claim that you won't be able to have a quantum desktop computer, because the computational purpose of a quantum computer differs from a desktop. Any insight and comment on that?

FTQC_researchers3 karma

For the first question, RSA encryption is the usual standard that people are referring to when they say that quantum computers will break "all" of cyber security. It's a very commonly used cryptosystem, and a fully functional quantum computer would indeed break it, but we're very far from that.

I do suspect that no one in the foreseeable future will have a quantum desktop. This is partly because we're still far from building devices with that kind of power, but also because quantum computers seem to outperform classical computers for only a relatively small set of tasks. It is likely that these tasks will be done by centralized quantum devices. Think about how a supercomputer of yore might be located in some basement of a university and people would have to apply for time on it. This will probably be the use case for quantum computers on the timescale of 20-40 years.

Steve

FTQC_researchers2 karma

Another topic I'm interested is about the claim that you won't be able to have a quantum desktop computer, because the computational purpose of a quantum computer differs from a desktop. Any insight and comment on that?

The kind of applications that we currently know about are solving science questions. No-one's yet come up with something that people at home will directly need a quantum computer for.

It may be that someone will find such an application, and so there will be a drive to get you a quantum computer at home. But it probably won't be us that find it. It'll be the quantum software engineers of the future.

James

FTQC_researchers1 karma

To answer your second question, it is unlikely we'd need a quantum computer on our desktops (just as we increasingly no longer need desktop computers on our desktops!) because we can easily access them remotely via the internet.

This is useful for quantum computing, since many of the leading technologies under development need to operate at temperatures close to absolute zero, so the quantum computer would need to sit inside a very very cold cryogenic fridge.

In fact, you can already access a prototype small quantum computer in this way via IBM's Quantum Experience:

http://www.almaden.ibm.com/cgi-bin/research_redirect.pl?quantum/

Dan

FTQC_researchers2 karma

As Steve said, quantum-computer resistant cryptography (sometimes called post-quantum cryptography) is an active research area and Google have already included one of these candidate protocols in their latest experimental builds of Chrome. https://security.googleblog.com/2016/07/experimenting-with-post-quantum.html

Dan

FTQC_researchers2 karma

Just to complement Steve's answer, even though quantum cryptography is claimed to be completely safe, there are always possibilities to circumvent the condition used in those proofs. For example, there are people studying quantum hacking

http://www.vad1.com/lab/

Xiaotong Ni

Gambito853 karma

How many hours each of you usually sleep?

FTQC_researchers2 karma

I get eight hours, it's tough to do research when you're groggy.

Ben

FTQC_researchers2 karma

I try for 8. My kids determine the duration more than work.

James

FTQC_researchers1 karma

Seven if I'm lucky - Earl

FTQC_researchers1 karma

As many as I can get, but about 7.30 on average. There's only a limited number of days your brain is any use with less that 7.

Mercedes

Vorthas3 karma

What is the most promising technological base used to build a quantum computer / set up qubits at the moment? And do you see any other technologies coming up in the future that could be used as well?

FTQC_researchers7 karma

I think we are hesitating to answer this because we don't want to break out into a fight. But the correct1 answer is spin qubits.

James

1 Not neccesarily correct.

FTQC_researchers5 karma

Scientists around the globe are currently pursuing different technologies, and we don't have a clear winner yet, it might even be the case that a hybrid of various technologies will be the best solution! Current favourites with the community are superconducting qubits and ion traps, however, there are other physical implementations that show great promise, such as integrated linear optics, quantum dots or topological quantum computing. A deciding factor will be the ability to scale up the technology, as at the moment any of these implementations can only handle few qubits. Technologies that can benefit from microfabrication techniques (such as the ones used in computer chips today) will be at a great advantage.

If interested I recently wrote a blog post summarising the main points about the four technologies most benefited by microfabrication: https://quantaforbreakfast.wordpress.com/2016/08/03/promising-implementations-of-quantum-computers/

Mercedes

FTQC_researchers4 karma

Honestly, I don't know that we've yet found the right physical hardware for large-scale quantum computers. In my opinion, the most promising candidates currently include superconductors and trapped ions. There are several other candidates: photons, semiconductor quantum dots, topological particles called anyons, and more. Currently, these other methods have some catching up to do, but really we're asking who is gonna win the marathon after the first kilometer of the race. The most likely future device will involve hybrids that incorporate the strengths of each of these while suppressing their weaknesses.

Steve

NewtonLawAbider3 karma

What are some of the differences between the quantum computers you research and something like Google's D.Wave?

FTQC_researchers3 karma

The D-wave quantum computers are analog computational devices. The vast majority of work on these devices does not use any error correction to stabilize the system against imperfections. By contrast, the quantum computers that the rest of us are working on incorporate both error correction (fixing errors) and fault tolerance (keeping errors from spreading). These devices will be able to achieve arbitrary precision computations and are essentially digital devices, not analog.

It is a bit like the difference between simulating an aircraft wing using a wind tunnel on a scale model (that's D-wave) versus a finite element analysis digital simulation (that's a standard quantum computer).

Steve

FTQC_researchers2 karma

Well, think of it as the Spaniards and Portuguese vying for discovering a direct sea route to the Indias in the 15th century. The Portuguese decided to circumvent Africa. Their first few attempts failed, but as they improved their ships and maritime technology, they eventually succeeded in circumventing Africa, and reaching India and China. They adopted a sound route, whose success relied on stepwise progress.

The Spaniards took the ships they had and sent them out in the unknown sea based on the (at that time unfounded) belief that there was no continent separating Europe and Asia from the east (contrary to popular belief, most savants of the day knew that the earth was round). They gambled with the technology they had at the time, and tried to see how far they would get with it.

We are taking the portuguese route, basing ourselves on stepwise progress to ensure that we will reach the ultimate goal of building a quantum computer.

D.Wave are adopting the spanish approach, except that they are using rafts rather than boats.

--Michael

FTQC_researchers1 karma

Google does own a D-wave machine, but they are made by another company (D-wave). However, Google are also developing there own superconducting quantum computer of the universal fault-tolerant type.

Earl

plopeek3 karma

Hi guys ! What if quantum computers never works ? Does your research have others application ? Could it be used in other branch of science ? Is it already useful somewhere else ?

FTQC_researchers3 karma

Ideas from quantum computing have already had a large impact on related fields.

Theoretical ideas have lead to insights into computer science, mathematics, and other branches of physics. For example, "quantum proofs" of classical theorems can sometimes be simpler in a similar way that using complex analysis can sometimes give a simpler proof of a theorem in real analysis. Ideas from quantum information have lead to methods to explore the physics of condensed matter systems in new and more efficient ways.

Experimental advances are leading to technologies that, while falling short of being quantum computers, nonetheless harness quantum phenomena in useful ways. For example, quantum devices are being developed that can sense small shifts in frequency or gravitational fields, and quantum cryptography is already a commercial product.

The fact that there are many exciting intermediate milestones along the way to a full-blown quantum computer is one of the reasons why I expect that quantum computing will be a burgeoning field for decades even though we won't all have quantum computers on our desktops.

Steve

FTQC_researchers1 karma

We and our research will just integrate into the closest area of physics, maths or computer science. Some research on quantum computation already has been used on unrelated problems.

James

FTQC_researchers1 karma

Many of the technologies we are trying to use for quantum computing are currently used for classical purposes. Any research we do in these areas goes towards understanding these systems better and hence making them more useful. For example, research in linear optics can improve optical communications while solid state research can improve classical memories. Also, the field of quantum technology is far larger than just quantum computing, and research in quantum information will also be useful there.

Mercedes

Donegan23 karma

Hey guys, I am currently going into the later years of secondary school and during this time I have finally decided to have a future career in physics, especially quantum mechanics. So during the last few months in my spare time, I've begun purchasing books explaining elements of QM and using web resources such as KhanAcademy to also further increase my knowledge. However, I don't feel like I've learnt enough from just ideas and explanations alone so I am very interested in exploring the mathematics behind QM. So my question is are there any resources you can link me which can explain some basic maths about QM or a way about learning the maths?

Thanks in advance :)

FTQC_researchers2 karma

The most important areas of maths for quantum computing theory are:

*complex numbers

*matrices

*group theory

Since you use the term "secondary school" are you in the UK? I'm British too and I studied all three of these topics in secondary school as part of my Further Maths A-level. So if you are UK-based a Further Maths textbook could be a good starting point.

Dan

Edit: For example, this book covers most of that material at A-level level: https://www.amazon.co.uk/Further-Pure-Mathematics-Brian-Gaulter/dp/0199147353

FTQC_researchers1 karma

"Quantum Computation and Quantum Information" by Nielsen and Chuang, "An Introduction to Quantum Computing" by Kaye, Laflamme and Mosca, "Quantum Computing since Democritus" by Aaronson, are some good books.

Christophe

lxbmxb2 karma

How can one as an individual access quantum computing, both in terms of physically acquiring hardware and also actually being able to use it for something (anything?), and how does accessibility look to be changing in the future?

FTQC_researchers1 karma

It's still a long time before individual can buy quantum computers of their own. So in the near future, individuals will likely access quantum computing in some cloud architectures. For example, IBM already has a website that allows users to access a very small quantum computer.

Also see https://www.reddit.com/r/IAmA/comments/49jkhn/im_bill_gates_cochair_of_the_bill_melinda_gates/d0sam8v

Xiaotong Ni

RosemaryAndChristine2 karma

Would spilling water on a quantum computer break it?

FTQC_researchers2 karma

It depends on the quantum computer, but a lot of the hardware that quantum computers are based on has to be sealed off from the outside world anyway. If you spilled water on the outside, likely nothing would happen. Some quantum computing experiments are even done inside these (chemist for scale), which you could splash some water on, no problem.

Ben

cristianbam2 karma

So twenty years ago we couldn't even dream of 10 core CPUs being accessible(-ish) to the average consumer. How long do you think it will be until we, as average consumers, will get PCs the likes of Quantum Computers into our homes?

FTQC_researchers3 karma

It will likely never happen, for two reasons:

1) the tasks that quantum computers significantly outperform classical computers seems not to be useful to household or entertainment tasks.

2) By that time, most of the actually computing will not be done on your smartphone or laptop, but rather on a computing cloud.

Michael

Sealatron2 karma

Is there any merit to the idea of a quantum computing device helping with video game physics simulations? I've often wondered about this.

FTQC_researchers3 karma

I'm not sure exactly how quantum computers might have gaming applications. Maybe it's the big secret behind the NX, and why Breath of the Wild is so delayed ;)

Thinking of gaming applications is certainly interesting, but I don't see that it will be taken too seriously. Though Microsoft has it's fingers in both pies, so we might wangle a bit of funding.

James

T1mac2 karma

In another question you said it will be 50 years before there's widespread implementation of personal quantum computing. What is the biggest barrier in getting this in widespread use, and what is the status of the hardware today?

FTQC_researchers3 karma

In "regular" computers, there's a hard disk which uses the stability of its small magnetic regions to store information for a long time, without consuming any energy, at room temperature. There are also logic circuits that can correct small deviations in the voltages they use to represent zeros and ones. These things mean that we can assume that the computer works while we're making up algorithms.

In a quantum computer, there are no guarantees. If you want to store a quantum bit reliably, you have to use a large number of the noisy quantum bits that exist in the lab. It's not clear what the best way is to go encode this information, or what constraints such encoding would put on the allowed processing operations. Though the hardware is getting better, and we're getting better at designing high-performance codes, it's tough to tell when these two efforts are going to start meeting in the middle.

Ben

T1mac2 karma

Thx

FTQC_researchers2 karma

No problem.

Ben

FTQC_researchers1 karma

50 years is fairly pessimistic, though it is comparable to the time it took between the invention of the transistor and widespread desktop computing.

One big difficulty in building a quantum computer is that we must control quantum bits (qubit) stored in individual atom, electrons or photons. This control must be exquisite. But such control is really difficult. Even if you can control a single qubit with precision 99% this means that every 100 computational steps, an error will occur. In a quantum computation with millions of computational steps, the output would be garbage.

At our workshop we are working to solve this problem using quantum error correction techniques. These are methods that allow us to reduce the physical noise by storing the data in quantum code. However, quantum error correction only works if the precision is already above some level we call the threshold. Newish theory ideas give a threshold of about 99%.

The really remarkable progress in hardware has been that we are now past the 99% mark. Recent experiments in Oxford even claim 99.9% precision. So one of the biggest barriers has been overcome!

However, we have only achieved this level of precision in systems of 2-8 qubits. The barrier we face now if how to "scale up" to many millions of qubits while maintaining the small level of precision. In different hardware platforms there are different obstacles to scaling up. Hope that helps :)

Earl

Statici2 karma

Perhaps a random question, but: Have you guys ever thought about designing the hardware of a quantum computer (maybe an adiabatic one) that uses Bayesian network "logic" rather than aiming for the traditional circuit model? Would such a computer be easier to build than a gate-based one?

And one other question...AdS/CFT relies heavily on quantum information. It provides ways to describe certain field theoretic problems, on a fairly abstract level, using spacetime equations. Has this ever, have you guys ever, considered using it to, for instance, design a topological quantum computer? (and if so, are there any direct tie-ins to figuring out ideal ways for built-in error correction using this correspondence?)

FTQC_researchers4 karma

I have a truly marvelous proposal for using AdS/CFT to build a topological quantum computer, but unfortunately this (3+1)-dimensional spacetime is too narrow to contain it.

Steve

TwoTonTuna2 karma

Are there any applications of many-body localization to quantum computing?

FTQC_researchers2 karma

Some have looked into it. Like me and others.

There'll be more recent work than that, but not that I think of atm.

James

adamisntdead2 karma

Hello! Doing a science-project contest, and my project is on developing a programming language for classical and quantum computing.... Anything you would like to see in a language - as such?

FTQC_researchers2 karma

I will shamelessly plug my stuff my suggesting you instead develop a decoding algorithm for quantum computation using /r/decodoku.

But in answer to your actual question, probably best to check out existing approaches to quantum programming languages. There's no specific wishlist I have for future ones.

James

FTQC_researchers2 karma

The number of algorithms that we currently know to be exponentially more efficient on a quantum computer is limited. At the moment we are in more dearly need of good control software for the experiments, and for that, you'd require a detailed description of the experiment in question. However, computer software aimed at the control and usage of quantum computers is starting to emerge. You might be interested in Microsoft's LiQUi|> simulator and the software developed by 1QBit.

Mercedes

ricksportalgun2 karma

Classical computer programmer here, I've got a couple questions.

With all the ways we can solve problems efficiently with classical computers, and the small subset of problems that can be solved with QC, how do you guys see the synergistic relationship of CC and QC moving forward? The way I see it a QC would make a good "sub-processor" for a CC, kind of like a class in OOP, where you can call upon the QC classically to return something that would take a CC longer to compute.

What do you guys think of new computing architectures like SyNAPSE? Could tech like this combined with QC possibly alleviate concerns about the Moore's Law ceiling?

I'm working in the IT field as a Data Analyst, but I've always been endlessly fascinated with academic research. I want to contribute, but I don't want to stop working either. I'm slowly working on my BS degree after obtaining my AA recently. Is there any way I can get involved with research if I'm not a full time student?

FTQC_researchers1 karma

About your last question, I do think machine learning can help the process of building quantum computers. In fact, I have a paper on using recurrent networks to help optimize some gate sequences for quantum memory.

Maybe one day we can have a Kaggle competition for quantum memory. But otherwise I would suggest you to be cautious of doing quantum computing research, as it will take a while for you to understand what are the problems we want to solve and what has been done.

Xiaotong Ni

FTQC_researchers1 karma

For the foreseeable future, we'll definitely be using classical computers to control and monitor quantum ones, so you can think of quantum computers as being co-processors.

On keeping Moore's Law going, there's some consensus that you have to get beyond transistor-based logic (quantum tunnelling implies that any sufficiently small transistor would basically be a conductor), since packing the elements into three dimensions raises heat dissipation issues. One promising way forward is to store information (classical or quantum) in the spins of electrons, which are too small to measure, and even too small for any physical theory to predict their size, so there's no fundamental limit to miniaturisation (heat dissipation is still necessary, though). We don't actually know a lot about neuromorphic computing, but if it uses transistors, it's still limited by the factors I mention above.

If you want to get into quantum computing, but don't have a lot of time, you can always try decodoku. If you get the high score, you may know something we don't about quantum error correction.

Ben

skylinx2 karma

If quantum computers are the future, what is the future of programming? (Worried junior programmer asking)

FTQC_researchers3 karma

There is very probably a lot of programming to do in any future coming. You have nothing to worry about :).

Christophe

pillowgrinder2 karma

Is it zero or one? tell me without YOU altering the outcome.

FTQC_researchers2 karma

I'll just entangle you to it. Then I didn't do anything that's not reversible, but you will know. Or both of you in different universes will know. Or something. It would be a great experiment!

James

ivanignatiev2 karma

Hi, thank you for such interesting topic! I have a lot of questions :) Where should start a classic computer scientist to master quantum computing? And what are most challenging problems today for QC to solve ?

FTQC_researchers1 karma

I would recommend the book by Nielsen and Chuang as a classical computer scientists entrance to the field. But if you are interested in the complexity side, there are probably better things to read that I don't know about.

James

Phantomdd872 karma

What is the best way to get into coding? I read a lot about apps to teach it and code dojo, would you recommend any in particular?

FTQC_researchers2 karma

I do a lot of coding, but I'm no good at it. So maybe I'm not the best to answer. But I'll answer anyway.

I think the best way to start is to try programming something. Making a simple game with Unity, for example, can be done without too much trouble if you already know some basics.

James

FTQC_researchers2 karma

0) Pick a language, say C.

1) Read the first few chapters of a decent text, say "Let us C".

2) Pick a fun and easy programming project and jump in even if you don't feel 100% prepared. For instance you could write your own version of the Game of Life (https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life).

3) Debug until it works.

--- Earl

FTQC_researchers1 karma

Second that, the only really good way is to pick something fun and attempt to code it. But I would not necessarily recommend using a book, there are loads of free online courses and resources such as codecademy.com and https://beta.hacksaw.academy that would make the process a lot less frustrating.

Mercedes

noobeeee2 karma

Explain quantum computing in ELI5?

Thanks

FTQC_researchers3 karma

I'm not sure I can explain quantum computing to a five-year old, but here is a great book (written by a quantum computing researcher at the University of Sydney) on quantum physics for babies!

https://www.amazon.co.uk/Quantum-Physics-Babies-Chris-Ferrie/dp/1492309532

Dan

FTQC_researchers1 karma

One inspiration of quantum computing is the many-world interpretation of quantum mechanics. So in some sense, you can think a quantum computer is equivalent to an exponentially many classical computers running in parallel, thus achieve a speedup. However, this explanation is not completely correct since it is very hard to extract relevant information from "the exponentially many classical computers".

Also note that nowadays many new quantum algorithms deviate from this intuition.

Xiaotong Ni

zyxzevn2 karma

Some deep scientific stuff here, which I love to read:
"There are no particles, there are only fields" Or:
"There are no particles, there are no fields"
And it raises some questions:
Isn't the concept of particles completely false? Does light or matter actually move in particles? How is light different from a wave? What are the alternatives? Does it affect quantum computing?

FTQC_researchers1 karma

Isn't the concept of particles completely false?

It depends what you mean by particles. I suppose a victorian understanding of them is false. But our current understanding is yet to be falsified.

Does light or matter actually move in particles?

Using the story (and maths) of light and matter moving in particles is helpful for predicting outcomes measurements in experiments, and also real life phenomena. So I think 'yes' is a more accurate answer than 'no' here.

How is light different from a wave?

Light is a type of wave. It's a wave in the electromagnetic field. But the energy of that wave is absorbed only in discreet chunks. So it also behaves like a particle. This is also true of other waves, like sound which can be explained in terms of particles called phonons.

For our everyday life, the size of the chunks is extremely small in comparison to the energy of light and sound that we deal with. So we don't notice the chunkiness. But all waves are chunky. And all chunks are wavy.

Does it affect quantum computing?

At some level, wave particle duality is quantum. So it makes QC possible.

James

SpaceAnteater1 karma

Back in 1998 I made a bet with someone that quantum computing would be in widespread use within 10 years. I lost that bet badly. Given the state of quantum computing now, if I were to make a similar bet now, when should I bet on widespread use of quantum computers? 5 years from now? 20 years from now? 50 years from now? maybe never? Would a quantum computation algorithm help in selecting the correct timeframe? :)

FTQC_researchers2 karma

It depends on what you mean by "widespread use". If you want to have a qLaptop that you can carry to the coffee shop, then you'll be waiting at least 50 years... at least 50 years. On the other hand, I suspect that in 50 years you will be able to access quantum processors remotely via the cloud. On the timescale of 5 years, we will only have very rudimentary quantum devices in my opinion perhaps with one or two logical qubits (i.e., stable encoded quantum bits). But I think that there will be many researchers that will be building and using these devices, so although the actual computational power of these devices is very small, this might qualify as "widespread".

Steve

jim_zzzz1 karma

what is the meaning of life?

FTQC_researchers7 karma

I asked my quantum computer to factorize 42, and it told me 6*9. I guess my quantum error correction needs improvement.

James

Jim1051 karma

Are there parts of the deep web that only quantum computer can access?

FTQC_researchers3 karma

Based on the Wikipedia's description

The deep web includes many very common uses such as web mail, online banking but also paid for services with a paywall such as video on demand, and many more.

I don't think quantum computing will change search engine in a way that it can index these part of the Internet.

One should keep in mind that quantum computers are only going to excel for a small range of applications. This is not because quantum computers are not powerful, but rather classical computers already filled most roles.

Xiaotong Ni

shiftynightworker1 karma

Does quantum computing represent the best chance at P=NP? (my wording's not great but I hope you see what um getting at in terms of better/faster algorithms?)

FTQC_researchers2 karma

YES ! In the sense that it is not a chance at all, like any other approach :).

Christophe

FTQC_researchers2 karma

It's the best chance at beating the limitations of P!=NP on normal computers.

James

Icarus13331 karma

Hypothetically, if Quantum Computing was successfully achieved, would it render the P=NP problem true?

FTQC_researchers4 karma

No, even if we had a full-scale working quantum computer this would still not resolve the P vs. NP problem. It's a mathematical question and no amount of physical hardware will be able to answer it conclusively.

Steve