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RECENT POSTS IN THIS TOPIC

Georgina Woodward: on 12/13/19 at 7:22am UTC, wrote OK

Lorraine Ford: on 12/13/19 at 4:45am UTC, wrote Georgina, I have no idea what you are talking about, or what point you are...

Georgina Woodward: on 12/12/19 at 23:53pm UTC, wrote Lorraine, you have identified two different kinds of phenomena. Those in...

Lorraine Ford: on 12/10/19 at 21:46pm UTC, wrote When discussing computers e.g. “What Will Quantum Computers Be Good...

Steve Agnew: on 12/9/19 at 4:58am UTC, wrote Quantum phase makes all of this moot...and the Stern-Gerlach device is an...

Lorraine Ford: on 12/8/19 at 20:47pm UTC, wrote Rob, When people write or speak, information is conveyed to others when...

Robert McEachern: on 12/8/19 at 0:56am UTC, wrote Let me try, one last time, to get through to you. Forget about physics. ...

Georgina Woodward: on 12/8/19 at 0:54am UTC, wrote Lorraine I think it may be helpful in general not specifically just for...


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Georgina Woodward: "OK" in What Will Quantum...

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FQXi BLOGS
December 13, 2019

CATEGORY: Blog [back]
TOPIC: What Will Quantum Computers Be Good For? — panel discussion from the 6th FQXi Meeting [refresh]
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FQXi Administrator Zeeya Merali wrote on Nov. 21, 2019 @ 18:08 GMT
Credit: Erik Lucero
Over the past couple of months there’s been renewed interest, and quite some intrigue, surrounding quantum computing. As you'll know from the special edition of the podcast with quantum physicist and FQXi blogger Ian Durham we posted in October, there was a news leak in September suggesting that a team at Google had achieved ‘quantum supremacy’ for the first time. This is the milestone at which a quantum computer performs a specific task that lies beyond the practical reach of a classical computer. At the time that we posted the podcast, the rumour was that Google’s quantum processor, Sycamore, had solved a random number generation problem in just 200 seconds. The claim was that the world’s best classical computer would need 10,000 years to perform the same task. Since then, the team has officially published their results in Nature.

Free Podcast

Quantum Supremacy Milestone? Rumours abound that Google's quantum processor Sycamore has performed a task that would flummox the best classical computer — a first in quantum computing. Physicist Ian Durham assesses the claims, gives us a quantum computing primer, and discusses concerns about the term 'quantum supremacy'.



LISTEN:







Go to full podcast

The plot thickened in October, however, when IBM hit back with a blog post in which some of their researchers claimed that the result was perhaps not quite as supreme as Google claimed, saying:

"Recent advances in quantum computing have resulted in two 53-qubit processors: one from our group in IBM and a device described by Google in a paper published in the journal Nature. In the paper, it is argued that their device reached “quantum supremacy” and that “a state-of-the-art supercomputer would require approximately 10,000 years to perform the equivalent task.” We argue that an ideal simulation of the same task can be performed on a classical system in 2.5 days and with far greater fidelity. This is in fact a conservative, worst-case estimate, and we expect that with additional refinements the classical cost of the simulation can be further reduced.

"Because the original meaning of the term “quantum supremacy,” as proposed by John Preskill in 2012, was to describe the point where quantum computers can do things that classical computers can’t, this threshold has not been met."

I'm sure Ian and I will be discussing where things stand in this debate during our end of year run-down on the podcast in a few weeks. But regardless of the status of this particular result, it's certainly worth talking more about the practical future for quantum computers. The random number task performed by Sycamore, which Ian chats about on the podcast, isn't a hugely useful one. The point of the test was just to show that quantum computers can do something that a classical computer cannot. But what do scientists hope quantum computers will be good for, eventually? That was the subject of a panel discussion at FQXi's 6th international meeting in Tuscany, featuring quantum physicists Scott Aaronson, of the University of Texas in Austin, Mile Gu, of the Nanyang Technological University, Michele Reilly, of Turing Inc, and Seth Lloyd, at MIT, all moderated by Catalina Curceanu, of INFN, Italy.

You can watch the full panel discussion now. Aaronson listed the most famous applications: simulating chemistry and physics (with applications in material science), breaking cryptography, speeding up database searches, enhancing machine learning, and using quantum computers to prove that random bits are really random. Gu looked further to the future, pondering whether quantum computers might help solve the quantum measurement problem. Reilly noted that however powerful quantum computers may or may not become, it is worth remembering that every quantum computer needs (costly) classical peripherals.



Lloyd meanwhile talked about what's already being done, and gamely sang a Gilbert and Sullivan inspired ode to quantum computers. Here are the lyrics for your amusement:

Qubit Willow

In a superconducting circuit a little qubit

sang Entangled, entangled, unentangled.

And I said to it `Qubit, oh why do you sit

singing Entangled, entangled, unentangled?

Is it just decoherence, qubit,' I cried,

`or a nasty quasi-particle in your little inside?'

With a shake of its poor little head it replied

Entangled, entangled, unentangled.

Its flux fluctuated as it sat on that chip,

oh Entangled, entangled, unentangled.

Its Josephson junctions were having a pip,

entangled, entangled, unentangled.

It sighed and it sobbed and a quantum jump it made

as it lost all the phase of its de Broglie wave,

and a spin echo arose from the suicide's grave:

Entangled, unentangled, entangled.

Now I feel just as sure as I'm sure that my name

isn't Engtangled, entangled, unentangled,

that it was not spontaneous collapse of the wave function that made it exclaim

Entangled, entangled, unentangled.

If my neurons interact with the universe I

shall decohere as it did and you will know why,

but I probably shall not exclaim as my decoherence dies,

Entangled, entangled, unentangled.

Seth Lloyd, FQXi, Barga Italy, July 2019

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Robert H McEachern wrote on Nov. 21, 2019 @ 19:28 GMT
"But what do scientists hope quantum computers will be good for, eventually?"

What they hope for and what they will ever achieve are two very different things. See my comments about this on the Quanta website here and here

Rob McEachern

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Lorraine Ford replied on Nov. 23, 2019 @ 21:05 GMT
Rob,

I agree that if quantum mechanics and thereby quantum computing is “based … upon a dubious interpretation of reality”, then the whole quantum computing edifice could possibly fall in a heap.

Your view seems to be that underlying quantum mechanics is a deterministic world, where relationships are representable by equations; and where the numbers for the variables that represent outcomes are determined by the equations. No matter what the situation, all outcomes are determined by the equations, not by the situation.

But surely the real question about the world is this: do the elements of the world ever respond to situations? Responding to situations can only be represented algorithmically e.g.:

“IF variable1 = number1 AND variable2 = number2 THEN variable3 = number3”

(where “variable1 = number1 AND variable2 = number2” represents the situation, and “variable3 = number3” represents the outcome).

Algorithms cannot be derived from equations i.e. you cannot get a world that responds to situations from a world that is representable by nothing but equations, variables and numbers. An example of a high-level situation would be a tiger approaching.

Surely we also need algorithms to represent the nature of the world?

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Robert H McEachern replied on Nov. 24, 2019 @ 16:02 GMT
"Your view seems to be..." No. My view is the exact opposite. In physics, both equations and algorithms are merely descriptions (AKA representations) of physical behaviors, not the behaviors themselves. Algorithms are simply more detailed descriptions (compared to equations) - providing essential details of the exact order of various behaviors, that are ignored in the equations. Equations only...

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Lorraine Ford replied on Nov. 24, 2019 @ 20:50 GMT
Rob,

Re “In physics, both equations and algorithms…”

We know what physics equations look like. Physics uses equations to describe the behaviour of the micro world.

Physics doesn’t use algorithms to describe the behaviour of the micro world, or anything else for that matter.

Can you give an example of a physics algorithm?

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Steve Agnew wrote on Nov. 24, 2019 @ 05:51 GMT
You know...these experiments seem like a lot of fun. The most important application for quantum computing is in modeling chemical bonds. It will be fun to see how well quantum computers can predict chemical bonds.

Then, the neural bonds of thought are also inherently quantum and it should be possible to model a moment of thought with a quantum computer. The quantum coin toss converges into a classical coin toss at some point and that might be fun to model.

Bottom line is that quantum computers are a solution in pursuit of a decent problem...

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Jason Mark Wolfe replied on Dec. 5, 2019 @ 00:56 GMT
Maybe a quantum gravity theory is more fun? What if it turned out that quantum entanglement between photons could store a gravitational field? We haven't performed that experiment. But what if it allowed us to build an Alcubierre drive, out of equilibrium? The laws of motion assume inertial reference frames, from a mathematical point of view. But there is fundamentally nothing stopping us from using entangled photons to create a non equilibrium fast travel condition to travel to Mars in a few hours. But when equilibrium is achieved, and conservation laws are satisfied, we've already beat Elon Musk to his Martian colony. Quantum entanglement could be the key to quantum gravity because the quantum states of position and momentum have to with the nature of spacetime.

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Eckard Blumschein wrote on Nov. 26, 2019 @ 19:31 GMT
"there’s been renewed interest, and quite some intrigue"?

Intrigue as a noun is according to my dictionary "the making of secret plans that are intended to harm other people".

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Lorraine Ford wrote on Dec. 4, 2019 @ 21:56 GMT
What is a bit (binary digit)?

A binary digit only exists as a concept in the human mind/ brain. The concept is instantiated in things and materials whose properties can be utilised to represent the concept. So electrical voltages can be used in computers to represent the binary digit concept.

The electrical voltages represent binary digits; and the binary digits in turn represent something else e.g. words, sentences, numbers and equations; and the words, sentences, numbers, and equations in turn represent the content of human consciousness.

The idea that binary digits could ever be context-free, or that binary digits are an actual entity that underlies physics, cannot be supported.

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Jason Mark Wolfe replied on Dec. 5, 2019 @ 18:38 GMT
Agreed. Binary digits don't support the underlying physics. The underlying physics is supported by unit quantities of action.

Jason

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Jason Mark Wolfe wrote on Dec. 5, 2019 @ 05:51 GMT
No reason why the physical universe can't be caused by a virtual greater universe of which layers of increased quantum entanglement are related to transcendent consciousness. Mathematicians might be fumbling a bit. But it certainly looks like disembodied consciousness is far more plausible than a fine tuned universe by accident.

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Jason Mark Wolfe wrote on Dec. 5, 2019 @ 05:53 GMT
No reason why the physical universe can't be caused by a virtual greater universe of which layers of increased quantum entanglement are related to transcendent consciousness. Mathematicians might be fumbling a bit. But it certainly looks like disembodied consciousness is far more plausible than a fine tuned universe by accident.

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Lorraine Ford wrote on Dec. 10, 2019 @ 21:46 GMT
When discussing computers e.g. “What Will Quantum Computers Be Good For?”, it is necessary to understand certain distinctions. But discussions on this and other websites, have revealed that most people, including physicists, do not understand important distinctions, and are not even aware that there are important distinctions:

1) What is a symbolic representation; what is a symbolic representation of a symbolic representation; and what is a thing that is not a symbolic representation. Human beings are so deeply immersed in many layers of symbolically representing the world and ideas that it can be difficult to notice these important distinctions.

2) What is the difference between an equation and an algorithm. I.e. what is the difference between a relationship (no steps involved or implied) and steps. An equation is a symbolic representation of a relationship using mathematical symbols like =, +, -, x, ÷ and √; but an algorithm is a symbolic representation of a series of steps taken, including questions asked, using logical symbols like IF, THEN, AND, OR, FOR and NEXT. An algorithm cannot be derived from an equation.

Equations and algorithms are evidence that two fundamentally different types of things exist in the world, because two fundamentally different types of representation are needed to describe the world.

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Georgina Woodward replied on Dec. 12, 2019 @ 23:53 GMT
Lorraine, you have identified two different kinds of phenomena. Those in which a relationship does not change and processes where there is change happening to relations. To be concrete consider an egg being hard boiled, peeled and sliced. That could be described in ordinary language, a flow chart or sequence of IF THEN steps. IF boiled solid THEN peel.IF peeled THEN slice. It is precise but not as succinct as boil hard (arrow) peel (arrow) slice. (arrow ) standing for an arrow symbol, meaning when completed go to next step. All are ways of representing the necessary sequence of steps in the process. Over the same sequence of configurations of the material universe/ existence the eggs not chosen have an unchanging relationship with the egg box put aside.

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Lorraine Ford replied on Dec. 13, 2019 @ 04:45 GMT
Georgina,

I have no idea what you are talking about, or what point you are making.

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Georgina Woodward replied on Dec. 13, 2019 @ 07:22 GMT
OK

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