Questions tagged [quantum-computer]
The quantum computing tag is relevant for computing that uses quantum states such as superposition and/or entanglement to locate low energy states as solutions to complex problems (rather than laboriously enumerating and checking solutions as would be done with non-quantum traditional computing). Also consider posting your question to the dedicated [quantum computing stack exchange](https://quantumcomputing.stackexchange.com/).
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Confusion on the difference between post-selection, approximate post-selection, and conditioning
(This question was originally posted on Quantum Computing Stack Exchange, but I did not get a satisfactory answer there.)
I have three questions concerning post-selections in quantum computing and how ...
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Why do random quantum circuits produce entanglement?
There's a lot of work done on random quantum circuits, and very often the story is that you start from a completely unentangled state, then random unitary gates act on it, and you generically end up ...
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Is qubit collapse in quantum computing related to decoherence, and how can probabilistic outcomes yield definite answers?
While studying Grover’s algorithm for quantum search, I came across an explanation that a qubit is represented as a state vector in superposition, with amplitudes corresponding to the probabilities of ...
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Is the boat analogy for quantum computing accurate, and if so, what can that tell us about its potential practical applications? [closed]
The boat analogy for quantum computing says that to call a quantum computer a better computer is like calling a boat a better car. The use cases for a boat and a car are too different for any ...
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Proof for the No-cloning theorem
So I was going through the proof for the no-cloning theorem, in quantum mechanics, which states that no arbitrary state can be cloned. The proof as mentioned on Wikipedia starts with $| \phi \rangle| ...
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If there are time-dependent coefficients on the left side of the equation, and a wave function on the right side of the equation, is that okay?
The state of a quantum system at time $t$ is given by the orthonormal base states $k$ and $j$, with probability amplitudes:
\begin{equation}
C_k(t_0 + \Delta t) \: = \: \langle{k} \vert \psi(t_0) \...
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Physical Means to State-Dependent Solutions to Schrödinger Equations? [closed]
Disclaimer: I am a mathematician/computer scientist interested in quantum computers.
Recently, I started reading about quantum computing, and I read that one uses unitary matrices since they ...
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Is there anything in quantum theory which permits to evaluate maximum time required for a measurement? [closed]
As far as I know, there is nothing in quantum theory or postulates that somehow places an upper bound on a measurement time. Since time is not really a physical observable in quantum theory, it is not ...
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Are there really zero Cooper pairs in the ground state of the Cooper Pair Box?
Trying to get an understanding of superconducting charge qubits. The literature I've read seems to indicate that the energy levels of the qubit correspond to the number of Cooper pairs on the ...
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I need help to understand strong symmetry Lindbad equation
I am in the process of constructing a Lindbad equation within strong symmetry regime for a two-level two qubit system.
$$
\dot\rho \;=\; -\frac{i}{\hbar}[H,\rho]
\;+\;\gamma\,\mathcal D_{\rm coll}[\...
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What's the difference between manipulating qubits and the Stern-Gerlach experiment?
In quantum computing, you can send qubits through one-qubit or two-qubit quantum logic gates in order to "rotate their Bloch spheres" (so to say) or entangle them. This can be done without ...
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A question in Lecture notes on Quantum Computation by John Preskill [closed]
I have been going through the 2nd chapter in the lecture notes on Quantum Computation by Prof. John Preskill. In section 2.2.1 on spin-1/2 particles, the author briefly discusses the theory of ...
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Warehouse of cats in boxes as a quantum computer? [closed]
Settings aside morality for a hypothetical question:
Wouldn't a warehouse filled with boxes, filled with cats, some sensors and deadly, radioactive isotope triggered contraptions, be a valid array of ...
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Does the use of trusted components align with the strict definition of device-independent quantum key distribution?
I am a novice quantum cryptography enthusiast writing on the topic for a short dissertation, so please forgive me if I make any incorrect assumptions or ask ignorant questions.
I recently came across ...
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If quantum physics is fundamentally random then how was Microsoft able to line atoms precisely to make a chip? [closed]
Sparked by this video with Microsoft's quantum chip: https://www.youtube.com/shorts/9SBVZr3lbS0
The video mentions how to get the array to work each atom had to be lined up exactly and that it took 17 ...
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