Author Topic: Google claims to have reached quantum supremacy  (Read 1075 times)

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Offline rfeecs

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Google claims to have reached quantum supremacy
« on: September 20, 2019, 10:44:39 pm »
https://www.technologyreview.com/f/614416/google-researchers-have-reportedly-achieved-quantum-supremacy/

From the FT article:
Quote
Google claims to have built the first quantum computer that can carry out calculations beyond the ability of today’s most powerful supercomputers, a landmark moment that has been hotly anticipated by researchers.

A paper by Google’s researchers seen by the FT, that was briefly posted earlier this week on a Nasa website before being removed, claimed that their processor was able to perform a calculation in three minutes and 20 seconds that would take today’s most advanced classical computer, known as Summit, approximately 10,000 years.

The researchers said this meant the “quantum supremacy”, when quantum computers carry out calculations that had previously been impossible, had been achieved.
 

Offline SilverSolder

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Re: Google claims to have reached quantum supremacy
« Reply #1 on: September 21, 2019, 12:20:26 pm »
Is it available as an Arduino shield?
 
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Offline Bud

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Re: Google claims to have reached quantum supremacy
« Reply #2 on: September 21, 2019, 12:24:18 pm »
Claimed by "google researchers", not verified by independent experts.  :=\
Facebook-free life and Rigol-free shack.
 
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Offline SiliconWizard

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Re: Google claims to have reached quantum supremacy
« Reply #3 on: September 23, 2019, 02:49:22 pm »
Also just look at the "but, but" paragraph.

Supremacy my ass. :popcorn:
 

Offline RoGeorge

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Re: Google claims to have reached quantum supremacy
« Reply #4 on: September 23, 2019, 04:28:39 pm »
I believe Google, just that they probably didn't use quantum particles to do the calculations.  With quantum particles there isn't much hope to scale up the number of qubits.

It is possible to run the same type of quantum algorithms, with the same speed advantages, using something very similar with analog computing techniques and true random noise.

Online wraper

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Re: Google claims to have reached quantum supremacy
« Reply #5 on: September 23, 2019, 04:33:30 pm »
It is possible to run the same type of quantum algorithms, with the same speed advantages, using something very similar with analog computing techniques and true random noise.
BS, maybe you heard about quantum analogue computing and made this nonsense conclusion.
 

Offline RoGeorge

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Re: Google claims to have reached quantum supremacy
« Reply #6 on: September 23, 2019, 05:08:12 pm »
I'm currently working at building one.  I don't want to publish before seeing it running, just to be sure the idea is correct.  The hardware is nothing like million $$$ cryogenic devices or so.  Instead, it is made with COTS (commercial on the shelf) parts, almost hobby level hardware.

Also, I'm not the only one trying to run quantum algorithms with all their speed advantages, but without using quantum particles.   

This month I learned that there are at least two claims (that I know of) that they already built running prototypes, and it feels very frustrating.  So far, they seem to be using different techniques than mine, so there is still hope that I'll not be totally scooped.

Online wraper

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Re: Google claims to have reached quantum supremacy
« Reply #7 on: September 23, 2019, 05:16:50 pm »
I'm currently working at building one.  I don't want to publish before seeing it running, just to be sure the idea is correct.  The hardware is nothing like million $$$ cryogenic devices or so.  Instead, it is made with COTS (commercial on the shelf) parts, almost hobby level hardware.

Also, I'm not the only one trying to run quantum algorithms with all their speed advantages, but without using quantum particles.   

This month I learned that there are at least two claims (that I know of) that they already built running prototypes, and it feels very frustrating.  So far, they seem to be using different techniques than mine, so there is still hope that I'll not be totally scooped.
Non quantum computer cannot have quantum superposition which is the reason of their calculation speed. You simply cannot do vast number of computations simultaneously on usual hardware.
 

Offline RoGeorge

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Re: Google claims to have reached quantum supremacy
« Reply #8 on: September 23, 2019, 05:52:09 pm »
Non quantum computer cannot have quantum superposition which is the reason of their calculation speed. You simply cannot do vast number of computations simultaneously on usual hardware.

That's exactly how I thought at first.  Now I think quite contrary.

Only when I went into details, looking at the hardware implementation of various types of existing quantum computers, I realized that it should be possible to implement the same functionality of qubits and quantum gates without using quantum particles.

Quantum superposition is not what makes quantum computing so special.  It appears to be so when looking at the formalism of quantum algorithms, but it's not the key element.  Of course, having this conclusions only on paper doesn't matter much.  They can still be wrong.  That's why I'm trying now to build a physical prototype, not just a software simulation, so to experimentally test those conclusions.
« Last Edit: September 23, 2019, 05:53:52 pm by RoGeorge »
 

Offline SilverSolder

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Re: Google claims to have reached quantum supremacy
« Reply #9 on: September 23, 2019, 08:41:16 pm »
Non quantum computer cannot have quantum superposition which is the reason of their calculation speed. You simply cannot do vast number of computations simultaneously on usual hardware.

That's exactly how I thought at first.  Now I think quite contrary.

Only when I went into details, looking at the hardware implementation of various types of existing quantum computers, I realized that it should be possible to implement the same functionality of qubits and quantum gates without using quantum particles.

Quantum superposition is not what makes quantum computing so special.  It appears to be so when looking at the formalism of quantum algorithms, but it's not the key element.  Of course, having this conclusions only on paper doesn't matter much.  They can still be wrong.  That's why I'm trying now to build a physical prototype, not just a software simulation, so to experimentally test those conclusions.

Superpositioning can of course be (slowly) simulated by a digital computer,  as we all know.  Are you saying you think it can be more quickly simulated on an analogue computer - perhaps some type of mesh architecture?

It is in any case always going to be slower than "the real thing" - no?
 

Offline rfeecs

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Re: Google claims to have reached quantum supremacy
« Reply #10 on: September 23, 2019, 08:49:20 pm »
Only when I went into details, looking at the hardware implementation of various types of existing quantum computers, I realized that it should be possible to implement the same functionality of qubits and quantum gates without using quantum particles.

I read something like that recently:
"'Poor man's qubit' can solve quantum problems without going quantum"
https://phys.org/news/2019-09-poor-qubit-quantum-problems.html
 

Offline rfeecs

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Re: Google claims to have reached quantum supremacy
« Reply #11 on: September 23, 2019, 08:57:43 pm »
This video may be what the Google paper is about.  (I found turning on closed captioning was helpful):
https://youtu.be/gylmjTOUfCQ

This sounds something like:
   I will prove that my quantum computer is superior to a conventional computer at solving at least one specific problem... and that problem is simulating a quantum computer.  :o
 

Offline RoGeorge

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Re: Google claims to have reached quantum supremacy
« Reply #12 on: September 23, 2019, 09:29:22 pm »
The YouTube video is from March, wasn't the retracted announcement of quantum supremacy from last week this month?

Yes the phys.org you posted is one recent announcement, from Purdue University, the previous one I know is from Linköping University:
https://phys.org/news/2019-09-poor-qubit-quantum-problems.html
https://phys.org/news/2019-09-quantum.html

And then is the retracted Google announcement, that nobody knows what it is about.

It was quite a sour surprise to see them popping all of a sudden, in the same month.   :-\

Offline RoGeorge

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Re: Google claims to have reached quantum supremacy
« Reply #13 on: September 23, 2019, 11:06:28 pm »
It is in any case always going to be slower than "the real thing" - no?

I think it will have the same speed as a quantum computer.

Same speed, and I'm not even considering the unfairness everybody is using right now to compare digital computers with quantum computers.  To detail what I mean by unfairness, when the big-O is calculated for a classic algorithm, they are considering only 1 bit questions, while for quantum algorithms big-O is calculated for questions about all the qubits at once.  I don't know why is this practice, is hard for me to believe that nobody really seen this unfairness.

For example, when the "guess my number" big-O is calculated, usually it is used the half-split method, so the question put to the "oracle" is "is your number in the first or in the second half of the given interval", and the oracle respond with yes/no, so only one bit, hence O(log n), while for the quantum algorithm they ask the oracle "what number did you pick", and the "oracle" answers with all the qubits at once by simply telling the number I chose, so the secret number is always guessed in one step, so O(1).  Very unfair way to question the oracle, if you ask me.  A fair thing would have been to use the parallelism for classic algorithm, too, not only for the quantum algorithm, and then the classic computer would have responded in 1 step, same as the quantum one.



At minute 27:27 there is a drawing of the quantum algorithm "guess my number", where the secret number (hardcoded) is 1101.  If instead of qubits we use normal bits, and instead of quantum CNOT gates we use classical XOR gates, then either the quantum or the classical computer will guess the secret number in one try, with big-O=1.

This suggests that there might be no advantage at all for quantum computers, but this is a software research and at the moment I'm interested in hardware.

Does anybody else noticed the unfairness when calculating big-O for the classical algorithm, or am I losing something obvious?
« Last Edit: September 23, 2019, 11:12:30 pm by RoGeorge »
 

Online Marco

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Re: Google claims to have reached quantum supremacy
« Reply #14 on: September 24, 2019, 03:23:44 am »
I googled for the paper so you don't have to.
 
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Offline RoGeorge

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Re: Google claims to have reached quantum supremacy
« Reply #15 on: September 24, 2019, 07:58:35 am »
Thank you for finding the paper.  :-+
Looks like they used a quantum computer indeed, their "Sycamore" processor.

What I don't get is if that is a scientific paper or a journal article.  Also I don't get it why?  Doing a research just to be able to say "Quantum Supremacy" seems to me like writing "First!" in the comments section of a YouTube video.   ;D  Must be something else I am missing.

Anyway, why did they take the announcement back?

Online maginnovision

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Re: Google claims to have reached quantum supremacy
« Reply #16 on: September 24, 2019, 08:00:12 am »
Maybe because it was a machine built to solve a problem rather than a machine you could make solve problems. That seemed to be IBM's issue with it.
 

Offline golden_labels

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Re: Google claims to have reached quantum supremacy
« Reply #17 on: September 24, 2019, 09:23:40 am »
People forget the history so easily!

Do you remember magnetism and then electricity? When they were very young? Everything was “magnetic” or “electric”, and that was widesread in quackery too. This is the same phenomenon we’re observing now with buzzwords like “quantum” and “AI”.

I believe Google might have created what they claim they did. There is no reason to lie for the very same reason US had no reason to fake moon landing: just like NASA had all the means of sending astronauts to the moon in 1969, quantum computing alone is quite boring news in 2019. Both just had to use the resources very well to achieve some new goal, which no one else have reached before. The catch is that Google hasn’t made anything extremely new. They made it “quantum” to bring media attention. At the same time they’ve probably progressed in data mining algorithms much more, but who wants to listen about crunching numbers, pages of maths and being 1.004% better than foo?

If the general public — and investors and speculators are the general public — doesn’t have a slightest idea about some topic, you can make them attach any meaning to it in their brains (in this case: “modern”, “faster”, “better”) and then use the term to invoke the corresponding feelings. It bears little resemblance to what is actually offered by given solution, but it sound good. And all the “buts” are needed, but they shouldn’t be seen as something negative. They’re inherent to the technology. Quantum computing will solve many problems much faster, but no one ever promised it will solve everything faster. There are problems, and most of those faced by an average person fall into this category, which are linear in their nature and using quantum computing will not make them magically faster. No, you will not get a billion FPS in your favourite game if you would run it on a quantum computer. ;)

RoGeorge:
Can you post a proof that, while resources grow linearly, the size of problems your computing method can solve grows at least exponentially with fast falling error probability? If not, you are missing something.
Worth watching: Calling Bullshit — protect your friends and yourself from bullshit!
 

Offline RoGeorge

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Re: Google claims to have reached quantum supremacy
« Reply #18 on: September 24, 2019, 09:32:25 am »
Maybe because it was a machine built to solve a problem rather than a machine you could make solve problems. That seemed to be IBM's issue with it.

My understanding is that the Sycamore chip is a generic quantum computer, and it can run various other quantum algorithms.  For that paper they program it with a specific quantum algorithm, one that will be particularly difficult to implement with a classic computer.

It is very hard for me to believe that Google will take the time to develop the Sycamore chip just to say "First!" in quantum supremacy.

Offline RoGeorge

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Re: Google claims to have reached quantum supremacy
« Reply #19 on: September 24, 2019, 02:20:16 pm »
RoGeorge:
Can you post a proof that, while resources grow linearly, the size of problems your computing method can solve grows at least exponentially with fast falling error probability? If not, you are missing something.

Not exactly a formal proof, but I can show an example that highlights why the computing complexity in terms of big-O analysis is the wrong question to ask.

Let's play again the "guess my secret number", this time with classical hardware only.  Somebody pick a "secret" number, in the range 0..255.  Let's try to find the secret number.

One approach will be to start asking one by one about each number:
- Is it 0?
- No.
- Is it 1?
- No.
- Is it 2?
- No,
... And so on until we find the "secret" number.  This algorithm will find the secret number in at most 256 steps.  In computer science, this algorithm is said to be be of a complexity of O(n), so at most 256 steps in our example

Another approach, much faster, is the so called "cut in half" method, AKA binary search.  Things go like this:
- Is it bigger than 127?
- No.
- Is it bigger than 63?
- Yes.
... And so on until we find the secret number.  This algorithm is said to have a complexity of O(log n), so in at most 8 steps for our example, it is guaranteed we will find the "secret" number.

OK.  Pretty boring so far.  Now, let's take a step back and see what we were really doing in the last algorithm.  In fact, we were asking for the secret number bit by bit.  Asking if the number was bigger than 127 is equivalent of saying "tell me the most significant bit of the secret number".  So, the binary search algorithm can be, as well, written like this:
- Tell me the first (most significant) bit!
- 0
- Tell me the second bit!
- 1
... and so on, until we get all the 8 bits of the "secret" number.

OK.  So what?  Well, there is yet another algorithm that is guaranteed to solve our problem in exactly one step, so O(1).  This best possible algorithm works like this:
- Tell me the secret number!   ;D
- 75.

Problem solved in one step.  Now, why we don't "ask" our classical computers just "tell me the darn answer", and solve any algorithm in one step?

The answer is trivial, but we were "trained" to disregard it.  Any classical computer is a 1 bit serial machine, AKA a Turing Machine.  Essentially, a classic computer executes everything step by step, with a width of 1 bit.  Yes, we do some tricks and now we all have 64 bits computers, but note that this 64 is a fixed number, no matter what algorithm we are running.  We can not truly adjust the number of parallel bits processing according to the solutions space of each algorithm.  We are doing the best we can we those 64 we have.  64 bits is better than a 1 bit Turing machine, but essentially it is still a serial machine.

What I am trying do show here is that the O(log n) limitation comes from the topology of current classical computers: they are serial machines, not parallel machines.



Now, even if it were to have computers where the width of a word can be adjusted upon wish, according to each algorithm, we still couldn't be as fast as an analog computer, or quantum one.

In fact, we already have the technology for adjustable width parallel digital computer in the form of FPGAs, so why the digital computer with a serial architecture is the king, at not the parallel computer?  Because parallel digital computing doesn't scale well with big number of bits, while the serial one can scale up pretty well, but only up to to a point.  From that point on, we realize that our serial architecture can not cope with some algorithms that tend to have a nasty big-O.

To conclude:

1.  For now we have the following technologies:
- one bit serial Turing machine
- a few bits (64) parallel machine, but the architecture is still a serial
- other tricks to achieve adjustable width parallelism (yet still digital), e.g. distributed computing, multicore, etc.
- purely parallel digital machines, like a FPGA
- then there is analog computing and quantum computing

2.  The problems where the number of steps for a given algorithm escalates too fast with big numbers might be mitigated by using parallel algorithms instead of serial algorithms.

3.  To mellow down the number of steps even more, instead of digital algorithms with only 2 states (0/1) per bit, we can try analog algorithms, where the number of states "encoded" by each "analog bit" is virtually infinite.  This is helpful because analog algorithms can operate now with a much broader range of values, virtually infinite number of values for each "analog bit".  In practice, it is not possible to get infinite resolution from an analog value, but still, it's better than having only 2 possible values per bit, as in the 0/1 digital computing.  Note that classical analog computing operates with contiguous values situated in R (real numbers).

4.  Then, there is quantum computing, where each qubit value is a contiguous range of values situated in C (complex numbers),  until the qubit is "collapsed" into a 0/1 at the final step of a computation (a contiguous C qubit is turned into a digital 0/1 bit by the measurement gate, which is always the last gate in any quantum algorithm).

In the end, the speed of solving a computation problem is given by a combination between algorithm type, numbers type (digital, real or complex) and computer architecture type (serial or parallel).  Ultimately, the proper combination between all these possible speeding factors is a mix dictatet by the availability technologies.

Offline SilverSolder

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Re: Google claims to have reached quantum supremacy
« Reply #20 on: September 24, 2019, 05:32:26 pm »
I get the sense that understanding quantum computing requires some kind of mental leap - it is not explainable in terms of classic computer science (or analog electronics)?

Each qubit is essentially in all possible states at the same time...   hard to implement when you're a dimension or two short of a dollar!
 

Offline SiliconWizard

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Re: Google claims to have reached quantum supremacy
« Reply #21 on: September 24, 2019, 05:39:24 pm »
And then, there's the quantum entanglement.
 

Offline RoGeorge

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Re: Google claims to have reached quantum supremacy
« Reply #22 on: September 25, 2019, 04:47:26 am »
I get the sense that understanding quantum computing requires some kind of mental leap - it is not explainable in terms of classic computer science (or analog electronics)?

Each qubit is essentially in all possible states at the same time...   hard to implement when you're a dimension or two short of a dollar!

A classic computer and a quantum computer doesn't have much in common.  It's like a crocodile and an airplane.  They both can "float" (calculate) except that one is swimming in a river and the other is flying in the sky.

A qubit is NOT in all the possible states at the same time.  That would be like saying a coin is both head and tail at once, which is incorrect.

Qubit.  You can visualize a qubit like an arrow anchored to a fixed point, but it can rotate freely around that point.  It's called a Bloch sphere.
https://en.wikipedia.org/wiki/Bloch_sphere

Entanglement is when you align the vectors of two or more Bloch spheres.

Superposition is when the vector in a Bloch sphere is oriented other than straight up or down.

A quantum gate "rotates" the Bloch sphere for a certain angle and in a certain direction, depending on the type of the quantum gate, or sometimes is "mirroring" the sphere.  Once you made yourself familiar with the Bloch sphere, you can open this webpage and run an example or build your own quantum circuit
https://algassert.com/quirk

Quirk runs in a normal webpage, nothing to install, and has "live" visualization of the intermediary values of the qubits at each step of the quantum algorithm/circuit.

Quirk is a quantum computer simulator, if you want a real quantum computer, you can make a free account to IBM-Q, and play with your own quantum circuits for free, either in simulation, or as a run on a real quantum computer.
https://www.ibm.com/quantum-computing/

Also, you need to FORGET about the cursed expressions like "Schrödinger's cat" and "spooky action at a distance".  Those are just wrong words used by journalist to confuse people and create hype.

Also, "quantum teleportation" is not teleportation in the sens that one object disappear from where it is now , then appears later in some other place.  "Quantum teleportation" is NOT teleportation.

One last thing, the formalism of qubits and quantum gates and quantum circuits stays the same between various types of quantum computers, but the hardware of quantum computers varies widely.  It's like C language stays the same either on paper, on a microcontroller or on multiprocessor server.

The hardware of a quantum computer can be made in many ways, either with trapped ions, or with photons, or Josephson junctions, or phonons, or some other crazy construction.  Also, to run a quantum computer you will need to control those ions/photons/junctions/whatever, so you will also need classic computer/s to "drive" the hardware of a quantum computer.
« Last Edit: September 25, 2019, 05:29:08 am by RoGeorge »
 

Online imo

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Re: Google claims to have reached quantum supremacy
« Reply #23 on: September 25, 2019, 06:22:31 am »
It would be great if somebody with experience with the quirk webpage simulator would create a new topic, in for example General computing section (ie called "Quantum computing basics") and create an example with explanation on how to play with the simulation (or provides some hints how to proceed with those examples there).
 ::)
 

Offline RoGeorge

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Re: Google claims to have reached quantum supremacy
« Reply #24 on: September 25, 2019, 06:57:32 am »
Quirk has instructions of how to use it https://github.com/Strilanc/Quirk/wiki/How-to-use-Quirk and a short video.


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