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My understanding of quantum computers is that it's a "let's get the universe to solve our problem" type of approach. This being said, it _feels_ like a massive

My understanding of quantum computers is that it's a "let's get the universe to solve our problem" type of approach. This being said, it _feels_ like a massive con to me. I'm 100% enthusiastic about fusion energy, and I get excited about most things physics related, but not quantum computers. What can be added to my set of physics knowledge to make quantum computers seem less imaginary?

golol 3y ago
I agree with you. Turing machines make sense and I can extend my intuition to a general idea of "dynamical systems can peroform computation", but I have no idea how quantum computing fits in there.
- hnfong 3y ago
  Quantum computing makes a couple algorithms faster but doesn't allow solving problems that we don't already know how to solve with a classical Turing machine.
bmer 3y ago
You probably ought to be more skeptical about nuclear fusion than quantum computing, to be perfectly honest: https://lucian.uchicago.edu/blogs/atomicage/2022/12/17/clean-energy-or-weapons-what-the-breakthrough-in-nuclear-fusion-really-means-via-the-wire/ https://lucian.uchicago.edu/blogs/atomicage/2022/12/17/clean...
philipswood 3y ago
My take on the origins of the field is that defining Quantum Computers was an outgrowth of trying to get at a "quantum observer" to make some headway in "understanding" quantum physics. I also feel it's a way to make the many-worlds interpretation of Quantum Physics more substantial - I mean, when you have a working QC, if the results of the computation isn't arising from interference between the many worlds, where are the calculations being done?
majoe 3y ago
tl;dr: Quantum computers are not only interesting for their practical applications, but also for furthering our understanding of Quantum mechanics. I had a similar feeling until I took a course on 'Theory of Quantum Information'. It cleared up some reservations I had about problems of Quantum Computing, e.g. error correction, and showed, that these are solvable (at least in theory). But more important, the lectures made it clear for me, that information is a physical quantity not less real than e.g. energy and that treating it as a non-physical "auxiliary" variable is core to many of the perceived paradoxes of QM. Also Quantum Computers try to make Quantum coherence work outside of closed laboratory systems, which not only pushes the boundaries of experimental physics, but also leads to interesting theoretical problems, since open systems don't exhibit a unitary time translation and are therefore not governed by the Schrödinger equation. These things together helped to spark a new interest in looking at the foundational questions of Quantum mechanics after decades of "Shut up and calculate".
- cmehdy 3y ago
  Do you have good recommendations to learn about this stuff? I've covered a decent amount of information theory, signal processing, systems control and generally relevant concepts in classical physics (boltzman, thermodynamics, the beginning of a hint of quantum chemistry). Your mention of everything being energy resonates (hah) with me of course, but quantum computing remains entirely elusive to me as both a structured framework of anything related to qubits and actual real-world things that will be made with it. Almost seems like quantum computing is so orthogonal to classical computing that you can only wrap your head around it as much as you can perceive a hypercube.
  - cevi 3y ago
    Watrous's notes are the best resource I know for learning quantum computing: https://cs.uwaterloo.ca/~watrous/QC-notes/QC-notes.pdf https://cs.uwaterloo.ca/~watrous/QC-notes/QC-notes.pdf
bobbylarrybobby 3y ago
Isn't all computation “getting the universe to solve our problem”? Classical computers just use the laws of electricity instead of quantum mechanics. Various historic computers, such as gear-based ones and water-based ones, have used other physical principles, but I think the only kind of computer that could be said to not just use the universe would be our own brains.

golol 3y ago

I agree with you. Turing machines make sense and I can extend my intuition to a general idea of "dynamical systems can peroform computation", but I have no idea how quantum computing fits in there.

hnfong 3y ago
Quantum computing makes a couple algorithms faster but doesn't allow solving problems that we don't already know how to solve with a classical Turing machine.

bmer 3y ago

You probably ought to be more skeptical about nuclear fusion than quantum computing, to be perfectly honest: https://lucian.uchicago.edu/blogs/atomicage/2022/12/17/clean-energy-or-weapons-what-the-breakthrough-in-nuclear-fusion-really-means-via-the-wire/ https://lucian.uchicago.edu/blogs/atomicage/2022/12/17/clean...

philipswood 3y ago

My take on the origins of the field is that defining Quantum Computers was an outgrowth of trying to get at a "quantum observer" to make some headway in "understanding" quantum physics. I also feel it's a way to make the many-worlds interpretation of Quantum Physics more substantial - I mean, when you have a working QC, if the results of the computation isn't arising from interference between the many worlds, where are the calculations being done?

majoe 3y ago

tl;dr: Quantum computers are not only interesting for their practical applications, but also for furthering our understanding of Quantum mechanics. I had a similar feeling until I took a course on 'Theory of Quantum Information'. It cleared up some reservations I had about problems of Quantum Computing, e.g. error correction, and showed, that these are solvable (at least in theory). But more important, the lectures made it clear for me, that information is a physical quantity not less real than e.g. energy and that treating it as a non-physical "auxiliary" variable is core to many of the perceived paradoxes of QM. Also Quantum Computers try to make Quantum coherence work outside of closed laboratory systems, which not only pushes the boundaries of experimental physics, but also leads to interesting theoretical problems, since open systems don't exhibit a unitary time translation and are therefore not governed by the Schrödinger equation. These things together helped to spark a new interest in looking at the foundational questions of Quantum mechanics after decades of "Shut up and calculate".

cmehdy 3y ago
Do you have good recommendations to learn about this stuff? I've covered a decent amount of information theory, signal processing, systems control and generally relevant concepts in classical physics (boltzman, thermodynamics, the beginning of a hint of quantum chemistry). Your mention of everything being energy resonates (hah) with me of course, but quantum computing remains entirely elusive to me as both a structured framework of anything related to qubits and actual real-world things that will be made with it. Almost seems like quantum computing is so orthogonal to classical computing that you can only wrap your head around it as much as you can perceive a hypercube.
- cevi 3y ago
  Watrous's notes are the best resource I know for learning quantum computing: https://cs.uwaterloo.ca/~watrous/QC-notes/QC-notes.pdf https://cs.uwaterloo.ca/~watrous/QC-notes/QC-notes.pdf

bobbylarrybobby 3y ago

Isn't all computation “getting the universe to solve our problem”? Classical computers just use the laws of electricity instead of quantum mechanics. Various historic computers, such as gear-based ones and water-based ones, have used other physical principles, but I think the only kind of computer that could be said to not just use the universe would be our own brains.