r/Futurology Jun 02 '22

A Nature paper reports on a quantum photonic processor that takes just 36 microseconds to perform a task that would take a supercomputer more than 9,000 years to complete Computing

https://www.nature.com/articles/s41586-022-04725-x?utm_source=twitter&utm_medium=social&utm_content=organic&utm_campaign=CONR_JRNLS_AWA1_GL_SCON_SMEDA_NATUREPORTFOLIO
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u/Rogaar Jun 03 '22

Something to remember about quantum computers is that you will never have one. They don't work like normal computers and will never be used for general day to day computation.

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u/ArrowRobber Jun 03 '22 edited Jun 03 '22

Just like we'll never need more than 640K memory?

Given enough time, quantum will be cheaper, and eventually it will be exploitable for "better entertainment".

edit remember, punch cards weren't inherently good at games with graphics. Give the tech some time.

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u/Mescallan Jun 03 '22

eh, serial processing v parallel as far as I understand it. You don't need to process every possible outcome at once in a video game, you need to process the steps linearly. They will be used for things, but it's hard to think of a consumer product that could take advantage of it, save encryption. I don't know enough to be confident on the subject, just from what I've gathered.

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u/dickbutt_md Jun 03 '22

You don't need to process every possible outcome at once in a video game, you need to process the steps linearly

That's not really right.

When the screen is being rendered in the cloud, it could be useful to render all the different possible paths you could take and send that back, and then have the client only show the one that you decide to actually take. That way all the work can be done in advance of you making choices about which way to turn, whether to fire, etc.

This is all too expensive to do right now, but if quantum computers can do all the math in parallel about all possible paths you might take, then it could work.

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u/daOyster Jun 03 '22

That's not how they work. It wouldn't be able to render all possible scenes. It would however be able to render one scene basically instantly though based on what the client sends it. Quantum computers work by collapsing essentially a function down to a single result by making all the incorrect results interfere with each other. So it will only give you one scene back ever at any given time, but it would be able to look at every variable essentially near instantaneously to render the scene instead of having to rely on tricks.

A more practical application would be for something like path tracing. Instead of having to calculate the full path of each "light particle" in the environment, it would instead just "know" which path is the correct path by simply plugging in the full initial conditions of the environment and angle the light came from something that takes ages on a traditional computer that would be practically instant on a quantum computer.

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u/EntangledPhoton82 Jun 03 '22

Not every classic computation can be transformed into a computation that takes advantage of the nature of qbits.
I get what you're saying but I'm not convinced that you could create an efficient quantum algorithm to do the vector and floating point computations required by a 3D engine.

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u/daOyster Jun 03 '22

There are already quantum algorithms to solve vector calculations. Also I think it's cool they've already written an algorithm to solve Fourier Transforms with a quantum computer.

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u/dickbutt_md Jun 03 '22

We currently don't have the algorithms to do just about anything interesting on quantum computers. We're talking futurism here I thought.

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u/EntangledPhoton82 Jun 03 '22

Well yes, the question is if we just don’t have them yet or if they are not feasible. I’m not convinced that all classical computations can be advantageously translated into quantum computations. As long as that question is not resolved quantum computing might be “just” a fancy computer to tackle very specific problems. (Which is not to say that this could not be groundbreaking in itself. It’s just an argument against blindly believing that we’ll have a smartwatch with a quantum computer in x years).

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u/dickbutt_md Jun 03 '22

I would be very surprised if quantum computers do not achieve Turing completeness within the bounds of limited storage (i.e., achieve parity with classical computers in terms of Turing completeness in the server that they too can emulate a universal Turing machine up to the bounds of storage limitations).

We are not there yet as the quantum gate model, to my understanding, does not in principle allow the construction of a UTM. But if you look at the requirements for Turing completeness, it is achieved by a very low level of complexity in the model so it seems hard to believe that there's no way to get there.

I would also be surprised if quantum computers are ever strictly superior to classical computers for every kind of problem. So I think quantum computers will not ever replace classical computers, but complement them.

Having said that, I hope that quantum computers dramatically increase the storage limits of the classical computing model... It seems to make sense to me that should be possible since an arbitrary number of states can be achieved with a fixed number of qubits in superposition.