26
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Effects of quantum computing on parallel universes
Regarding your first question, you are essentially asking about the validity of a position taken by David Deutsch - a founder of quantum computing! For example, in his book 'The Fabric of Reality', ...
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16
votes
Accepted
Effects of quantum computing on parallel universes
Question 1
This description lies somewhere between the two extremes of a theory and mysticism, depending on how amiable one is to the concept. David Deutsch is vocal proponent of the former, Lee ...
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9
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What are tentpole topics in quantum computing?
Made Community Wiki
Much as there's no royal road to geometry, getting familiar with quantum computing usually takes a lot of hard work. I would consider anyone who can answer Bertrand's questions in ...
9
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Effects of quantum computing on parallel universes
In the many worlds interpretation (MWI) reality consists of a structure called the multiverse that looks like a collection of slightly interacting parallel universes in some circumstances:
Deutsch, ...
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7
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Accepted
How can quantum interference happen in real world if a wave function does not have any physical meaning?
The assertion that the wavefunction has no physical meaning might mean different things in different contexts.
Wavefunction is unobservable
In one interpretation the assertion simply means that the ...
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6
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Interpretations of quantum computing power
1 and 2 have elements of truth, but are only partially correct, with big caveats.
3 and 5 are complete nonsense.
You can choose to read 4 the right way to make some sense out of it, but it doesn’t ...
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6
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What is the "sum-over-paths" picture of quantum computing?
Expanding on Mark S's answer with some math:
Let's take Aaronson's example, where you are applying the following unitary $U$ twice to a qbit initialized to $|0\rangle$:
$$
U =
\begin{bmatrix}
\frac{1}{...
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5
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Does a classical computer really require $2^n$ complex numbers to represent the state of $n$ qubit quantum computer?
If you treat the gate sequence as fixed then by the same logic you can treat the actual gates as fixed. No parameters is better than polynomial number of them :)
But the problem is not with this. ...
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5
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Does Planck's constant have any role in quantum computing?
Great question, and David Mermin dedicates an entire section of his great paper "From Cbits to Qbits" to it:
Like my disapproving colleague, some physicists may be appalled to have finished ...
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5
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Accepted
What is the "sum-over-paths" picture of quantum computing?
Initially perhaps it is best to compare and contrast a couple of different approaches to simulating the output of a random quantum circuit $U$ of about $m=1000$ gates acting on, say, $n=53$ qubits ...
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5
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Accepted
Simulating a system inside a system
tl;dr- Quantum computers can't really help us to simulate the whole universe as the universe is likely vastly more complex than even quantum mechanics can capture, plus we can't even begin to guess ...
- 1,497
5
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Many-Worlds Interpretation and GHZ States
I should probably start by describing my philosophical standpoint: I would never talk about "many worlds" or some such. However, I certainly believe that it is possible that everything, including ...
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3
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Does a classical computer really require $2^n$ complex numbers to represent the state of $n$ qubit quantum computer?
The issue is that you are confusing the notions of Komogorov complexity and computational complexity. Kolmogorov complexity (roughly) means the smallest amount of data that you need to provide in ...
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3
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Accepted
How similar is the recent (2021) tardigrade experiment to a Schrödinger's cat experiment?
I would say that this experiment is not at all similar to preparing such a cat-state, because no measurable property of the tardigrade was ever probed, or rather, that the measurable property is not ...
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3
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Does the Copenhagen interpretation (+ "quasi-classical measuring apparatus") allow one to bypass a derivation's objection?
There are a lot of comments and objections in the question, too many in fact to go through them all. I will try to address some of the points that I think hide misconceptions, to hopefully give a ...
glS♦
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3
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In $|x_1,...,x_n\rangle$, can the individual constituents be called qubits?
The $|x_i\rangle$ you mention here are qudits, they are the generalization of qubits to base $d$ with $|S| = d$. It is categorized by a superposition of $d$ states, same way a qubit is described by ...
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3
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Does Planck's constant have any role in quantum computing?
I like this question although the question and answers may be a bit vague/a moving target.
Initially I'll quote Gil Kalai who asked a very similar question on MathOverflow:
the Planck constant ...
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2
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Does Planck's constant have any role in quantum computing?
Time evolution of quantum systems is described by Schrodinger equation
$$
i \frac{h}{2\pi}\frac{\partial}{\partial t}|\psi(t)\rangle = H |\psi(t)\rangle.
$$
So any change on quantum computer can be ...
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2
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What is the reason of $ZZ$- and $XX$- interaction in two-qubit system?
This comes down very much to the physics of the individual devices. I'll describe here one relatively simple model which hopefully gives you a little bit of insight. But, as I say, it's different for ...
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2
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How similar is the recent (2021) tardigrade experiment to a Schrödinger's cat experiment?
Firstly, they did not prepared tripartite state as they claimed. The tardigrade simply plays role of a dielectric in shunt capacitor on qubit B. As a result, resonance frequecny of qubit B changed due ...
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2
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Does a classical computer really require $2^n$ complex numbers to represent the state of $n$ qubit quantum computer?
I believe the issue you are missing is entanglement, which is an essential resource in quantum computing algorithms. Since we generate entanglement between these qubits, we can no longer think of ...
2
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Does a classical computer really require $2^n$ complex numbers to represent the state of $n$ qubit quantum computer?
As Danylo Y have answered, the key is you don't need to read out the entire quantum state at the end of the quantum algorithm to get your answer. There is another algorithm, called HHL algorithm, ...
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1
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Interpretation of a circuit that yields the same result for initializations $|+\rangle$ and $|-\rangle$
The way to think about the circuit you showed (and it can generalise to some multi-qubit cases) is that when you measure, you collapse the qubit into a particular state, 0 or 1. You can now run the ...
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1
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How can quantum interference happen in real world if a wave function does not have any physical meaning?
I don't think it is particularly meaningful to say that a wavefunction "does not have physical meaning". It absolutely does: it tells you the probabilities of observing different outcomes in ...
glS♦
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1
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Does a classical computer really require $2^n$ complex numbers to represent the state of $n$ qubit quantum computer?
Consider an $n$ qubit system. For each qubit you need to store 2 complex numbers, making $2n$ numbers in total. But if these qubits are entangled, then you can no longer store those numbers separetely....
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Many-Worlds Interpretation and GHZ States
You are 100% correct that this question has nothing to do with the Everett interpretation (also known as "many-worlds interpretation") of quantum mechanics, and in fact I would even agree ...
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