The Ugly Truth About Quantum Computing

I keep seeing it, everywhere - and I am sure you do, too: "Quantum computers will someday rule the world!" "Quantum computers will bring miracles!" "Quantum computers will lead to the Singularity!"

The picture above is an example of New Age movements that go as far as believing that quantum computing will bring happiness and godly powers.

Quantum computing has become a magic word, if you say it, then it makes you look all cutting edge and smart.

But I am getting tired of the same old rethoric. Because the truth is, in real life, Quantum Computing actually is highly inefficient, and big time - even in the best case scenario.

First off, what some manufacturers and researchers call "quantum" computing might not actually be even true quantum computing, as recent evidence suggests:

Back in 2011, the aerospace giant Lockheed Martin paid a cool $10 million for the world’s first commercial quantum computer from a Canadian start up called D-Wave Systems. In May last year, Google and NASA followed suit, together buying a second generation device for about $15 million with Lockheed upgrading its own machine for a further $10 million.
These purchases marked the start of a new era for quantum computation. Theoretical physicists and computer scientists have been predicting for 30 years that quantum computers can dramatically outperform the conventional variety. And in May last year, these dreams at last appeared to be coming true when Cathy McGeoch at Amherst College in Massachusetts said she’d clocked the D-Wave device solving a certain class of problem some 3600 times faster than a conventional computer.
This finally backed up D-Wave’s long-pronounced but never confirmed, claims that their device was indeed faster than anything else at some tasks. Never had quantum computing’s stock ridden so high.
Since then, quantum computing—at least, D-Wave’s version of it— has undergone a dramatic change in fortune. And that culminates today with a report from a team of physicists from IBM’s T J Watson Research Laboratory in Yorktown Heights, NY, and the University of California Berkeley, who say that D-Wave’s machine may not be quantum at all. Indeed, its results could be just as easily explained if it was entirely classical.

Bit of course, the D-Wave is not the only quantum computing project getting funded by various agencies and taxpayers money. So let's forget the D-Wave a bit and actually get a look at the science of it.

A qbit (quantum bit) can store more info than a bit; this is because unlike a classical bit, which can either be 0 or 1, qbits can be anything between 0 and 1, inclusively. This is due to quantum uncertainty principle.

However, although qubits can in theory hold more information, the result isn't necessarily a more efficient computer.

A first problem with quantum computing is how to make a qubit, in the first place. Believe it or not, trapping a particle for it to be used as a qubit is rather difficult to do.

Some techniques involve trapping ions, electrons or other tiny little particles; some propose using superconductors to create microscopic quantum circuits; others suggest it might be possible to use photons and complex optical apparatus to achieve a similar goal. What these techniques all have in common, however, is the fact that they’re currently plausible on the small scale but incredibly difficult to realize on the large. Essentially, that limits quantum computers to research machines, at least for now.

source: gizmodo.com...

But that's not all. Remember when quantum physicists say that observing a particle will cause its wavefunction to collapse? Well, qubits are no exceptions.

The problem is that, as good ol’ Schroedinger was only too keen to point out, quantum systems need to be isolated from the rest of world in order to work. Interactions with the external world cause the system to decohere, collapsing down and taking a binary state, just like a normal computer.

Basically, any interaction with the outside, or even with the computer's internal components, and poof, no more qubits. Of course, there is a solution for that:

The solution? Decide on an error rate—the amount of dechorence you’re happy for the system to put up with—and design for that.

So, we're allowing the computer to glitch, we're simply determining how much glitches to ignore.

Even that's an imperfect solution, though; to have an error rate small enough that you're still getting the benefits of a respectable quantum computer, you’d need a weighty bump in the number of qubits to provider error correction, and those qubits are extremely difficult to produce in the first place, which… well, you can see where that goes.

So. To compensate more glitching from the qubits, you make more qubits. Well, I guess that could somehow work. But, um, how do we program a quantum computer, anyway?

First, there’s the question of knowing if it’s even working in the first place. A widely known tenet of quantum mechanics is that merely observing the phenomenon changes the outcome of an event. So, watch a quantum particle, or a qubit, or anything quantum for that matter, and you change its behavior. That means that it’s actually very difficult to tell if a quantum computer is behaving in the way we’d expect or need it to.

In fact, the currently available so-called quantum computers aren’t actually verified to be working the way they're supposed to. They’re simply based on the right theory, some fingers crossing, and judged by their output.

Unlike a traditional machine, you just can't open the lid and check if it actually works like intended; because if you do you screw up the whole thing. So you can only hope that it's working as you want it to.

Coding a quantum computer is no mean feat; by their very nature, they give answers that are necessarily probabilistic, not concrete. For many solutions, that means that the answer isn’t necessarily bang on at first attempt; instead, the same calculation has to be repeated a number of times before the obvious correct answer emerges. In turn this means that, depending on the type of problem, there isn’t necessarily a huge amount of advantage in using a quantum computer compared to a regular one.

To get this straight: not only is programming the thing a nightmare, any program you code will actually give inconsistent results, and so you have to run the program a whole lots of time, so to eventually get the right result. This is similar to using a dice as a "computer". 6 divided by 3 should give 2, but rolling the dice, you will get random results, until some day you get "2".

But quantum computing is not useless. In fact it has one very clear application.

It's possible to exploit some of the mystical magical power of quantum mechanics to improve the speed with which solutions are reached, but so far researchers have only managed to do it for a very small set of problems, like finding the prime factors of very large numbers. That’s neat—and, it turns out, useful for cryptography—but it’s certainly limited.

Cryptography. So, basically, could it be that defense agencies are those that would benefit the most from quantum computing researches?

Bingo.

The most concerning advantage relates to codebreaking. Today, communication networks pass digital information over public infrastructures, such as fiber optic pathways and wireless airwaves, using encryption to prevent eavesdroppers from reading the content of the message traffic. The only thing stopping eavesdroppers from decrypting this traffic is the mathematical complexity of doing so. Quantum computers will have the ability to crack these codes in far less time than today’s most advanced conventional computers. Furthermore, as quantum computers make linear gains in computational power, they will exponentially decrease the time it takes to break current means of encryption.

source: foreignpolicy.com...

Could it be that this is the true intended purpose of quantum computing researches - not something that will actually improve our computers storage space or let us make faster programs, but actually a new tool for country agencies to spy on other people?

Hence, this is why I think quantum computing, as presented in everyday media, is not our "Messiah" or the thing that will "revolutionise our lives".

Sounds like someone, just after the Model T hit the streets, screaming the Mclaren F1 isnt feasible.

a reply to: IgnoranceIsntBlisss

More like, agencies promising us that they'll make a McLaren, but actually building a Model T.

A Model T that is however good at one thing: listen to encrypted messages.

How To Get Financial Support From Taxpayers To Fund Your Personal Spy Tools, For Dummies



Quantum Computing *is* feasible, in my opinion. It just has a very much different purpose than what they're telling you in sci-fi movies and popular media.

Knowing a bit of programming, I can actually confirm some of the conclusions from the source in my OP. It's not about "yeah, just give it time, and it'll work", it's about plain physics and computer science.

I sometimes wonder about harmonic acoustic resonance and the concealed and forgotten portion of quantum computing. It seems a quantum box may be almost like a spirit box if you will. Then there is vibrational coding for how one could or maybe programming their system.
Let's talk about filters for information being a way to interpret information sending and receiving thus tranceiving. So a Quantum Tranceiving station centered around a box or a stack like a antennae could be filtered by white noise or some kind of harmonic acoustic resonance all the time. This way information can be more fluently related between perhaps many quantum tranceiving stations or quantum broadcasting stations.

All the while I wonder about also a cymascope that reads and interprets too so a computer feed can be interpreted as 3D or Holographic Information on a hard drive.

a reply to: swanne

This assessment is not really accurate. We are in the early stages of understanding how to process the information in superposition without using classical methods but the advances are happening very quickly. Moores law sort of applies here.

For instance moving from 17 to 49 qbits a huge breakthrough happened basically months apart by researchers. Tech people talking physics isn't always a good representation.

Now we are maybe a decade away from non cryptography uses in a practical sense but it's not far off. The chinese in particular are charging ahead with a lot of research in the area.

Expanding on advancement in quantum mechanics and in Q. E. a few links of some recent publishings in the field which will help create quantum computing among other things.

theconversation.com...


phys.org...

phys.org...

Basic summary of advancements.

www.independent.co.uk...

youtu.be...

Edit video added for general reference.

Quantum processors are interesting but far removed from what I think I will ever see.

I think bio computers may one day be coming to a shopping mall near me. At least I hope.

a reply to: swanne

Ya pretty much. Here's a quantum circuit simulator so you can see for yourself how frustrating it is.

algassert.com...

I've also taken a look at Microsoft's Q# quantum programming language and the operations on qbits are fairly limited.

a reply to: Grimpachi

Biocomputers, now were talking.

What about bioenergy mechanisms, anyone?

Quantum computers are at the same level as ladies wearing rubber Wellingtons at Bletchly park in the mid 40's and thus we're in wild west land and the bang per buck aint near worth it especially seeing the gear that you need.

Much of the hype behind quantum computing is the fault of popular science and the media not painting a realistic picture... and then that being perpetuated and exaggerated way out of shape.

Too common is the idea that a quantum computer is so much faster than a conventional one, that it would be 1000 times faster at all tasks.

Closer to reality is
A quantum computer has the potential to be 1000s of times faster at solving specific tasks, for others though, they can be on par or even slower than a conventional one.

Media love hype, and far to often hype results in these complete fantasy like misrepresentation of reality.


as an aside the other thing i can think of like it is string theory.... people speak of it like it is a done deal... when the truth is that, there are many different string theories and none of them have managed to prove or do anything beyond what the standard model predicts.

a reply to: ErosA433

The hype around quantum computers is real and very much something physicists are excited about. So is the nsa.

Quantum mechanics is a "done deal" so to speak
There is no more proven branch of physics than qm. It is used on a daily basis and is at the same time vastly not understood by most people who use its formulas to "make predictions" fpr things like chips. So it is also true in the larger ontological and cosmological sense we have no idea what it means.

Quantum computers may be a decade off from practical use but not in all cases. What people don't understand is it is almost like analog vs digital. It is far superior to binary in terms of information theoreticly processable. Let's take 1 and 0. In quibits this doesn't exist. There is 00 01 11 10 all possible. You can have 90 percent 0 and 1 percent 1 etc. You are processing information at a massive speed difference. It's true there will be certain functions at first better suited like cryptography. And yes the more quibits the more chances of them rubbing up on each other and making "observations" but the advancements in this field of physics are happening rapidly. The explanations by places like wired are poor and they often don't have physicists explaining the process at all.

Personally I believe QM's many world's interpretation of reality. I think it's testable as well.

When we have the algorithm basics down in quantum computing which likely is less than a decade away QC will evolve quickly. Problems that would take 1000 years to simulate like with billions of variables will be possible to solve.

i read some interesting info a while ago... how quantum computers get the answer they are looking for.....

Quantum annealing (QA) is a metaheuristic for finding the global minimum of a given objective function over a given set of candidate solutions (candidate states), by a process using quantum fluctuations.

Nice

a reply to: swanne

D-WAVE ain’t quantum. Period. It does quantum like calculations that regular classic computers would find difficult. It is very specific in what it does but still is not really quantum computing.

Real QC is at the vacuum tube stage! It is noisy, takes too much energy, is not fully known, and fails more than it succeeds. It barely works as is and is mostly still lab top demonstration stuff. They ran hundreds of thousands of runs on IBM and Rigetti QC chips and were not impressed. IIRC, something like Shor’s algorithm. Anyway, inconsistent results with them having to average data returns.

Thing is, you need to understand QM and linear algebra (and what your results mean) in order to use QC effectively. Which means that you need to know bra-ket notation. Pseudo-python or pseudo-C++ means nothing.

When it does happen, millions of particles finding quantum states that can be useful to humans will change our world. Just don’t think it is 5 years out ( despite my early enthusiasm)!

@ATS, read Swanne’s thread on an intro to quantum mechanics! Good stuff!

a reply to: swanne

Since when do any of the tech of tyranny agencies have to sell anyone on anything? Since 2005, all I've ever seen is blank checks and back slapping.

I agree that biocomputers is more viable and probably more efficient solution. Encoding information into DNA molecules has already been done with incredible success, a huge amount of data can be stored that way, and I expect such a computer to be rather lightweight, especially compared to quantum.

With four molecules (base-4) you can already have an improvement over classic bits (which are base-2). And it remains intuitive enough that we programmers can already design powerful programming languages for it.

I think in the future we won't be limiting ourselves to DNA base-4 biocomputers, but will actually grow to design synthetic macromolecules that might integrate even more bases. Let's not forget that technically, DNA doesn't have only four bases, more bases actually already exist and can in theory be added. Which would increase the efficiency even more.

2^3 equal 8 permutations.

4^3 equals 64 permutations.

This is a considerable increase in capacities.

a reply to: swanne

If you look at QC from a "IT" perspective I can see your point. However, if you understand the functionality of superposition and entanglement research and how branches of physics that have nothing to do with trying to create a computer are feeding QC researchers it's pretty easy to see this is going to accelerate quickly. Encryption uses have already begun to have working satellite models. As researchers continue to use superposition and entanglement in applied science to create artifacts the process will accelerate.

Focusing on what a Quantum computer could do even 1 year ago is not an acurate way to Guage it's use or effectiveness. The formulas and algorithms that are being worked out are the key. As scientists figure out how to keep from observing the particles as they increase the information the functionality will see doubling, tripling, etc as the one algorithm leads to the next.

Will they be in people's homes? I don't know but that isn't the point. The point is to continue to understanding how QM can be used in applied science.

Biocomputers will have their function and limitation (speed and programming and unknown scalability function)

a reply to: TEOTWAWKIAIFF

This is true, however Regetti is pulling off some impressive results (from a R &D perspective). I feel that judging the functionality of prototypes and comparing them to a MacBook isn't really accurate. The algorithms for having enough q bits to be actually functional are certainly no available. But I feel like the critique is a bit like watching the first space x rockets fail and then assume the space shuttle is obviously more practical.

Personally from a physics and qm perspective I see the future is in QC. It just may be a decade away before we have the type of functionality IT can use more broadly. I have a tendency to explore cosmology so I am very excited to see what modeling can be done.

originally posted by: swanne
However, although qubits can in theory hold more information, the result isn't necessarily a more efficient computer.

You say more efficient but I wonder if you meant faster? Regarding speed, I think this assessment is correct:

originally posted by: ErosA433
Closer to reality is
A quantum computer has the potential to be 1000s of times faster at solving specific tasks, for others though, they can be on par or even slower than a conventional one.

That's my understanding also.

If you really want to talk about efficiency, we'd have to clarify what that means, but one possible definition could be something along the lines of calculations per joule of energy consumed, though that could have other meanings too, but let's look at that meaning.

One thing that I've read about quantum computers is that they require cryogenic cooling to operate.

theconversation.com...

quantum devices using atomically heavy materials such as silicon or metals need to be cooled to low temperatures near absolute zero...the refrigeration systems required to cool materials close to absolute zero can cost upwards of millions of dollars and occupy physical spaces the size of large rooms.

The operating costs of running those cooling systems isn't cheap either.

That source then goes on to say that maybe someone can make a room temperature quantum computer derived from mothballs, but nobody has done it yet. That would be an interesting development to me, to avoid the need for all the cryogenic support apparatus.

I agree with everyone who said it's a little over-hyped by the media, that's my take also.