Unanswered Questions
2,313 questions with no upvoted or accepted answers
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What is the quantum bandwidth of a planar array of noisy qubits, assuming free classical communication?
A common task to perform during quantum computation on the surface code is moving qubits from one place to another. There are standard ways to do this within the surface code, but I was wondering what ...
CommunityBot
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How can blackholes be fast information scramblers?
I noticed that there was already a post discussing the fast scrambling property of black holes. But it seems no satisfactory answer was given.
As mentioned by L. Susskind et. al, the fast scrambling ...
glS♦
- 25.7k
7
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What do "$i$-th basic network", "quantum multiplexers" and "quantum parallelism" mean in this context? How are they beneficial?
I have been reading the paper A quantum-implementable neural network model (Chen et al., 2017) for a few days now, but failed to understand how exactly their algorithm offers a speedup over the ...
CommunityBot
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6
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Universal gate set for the $ [[15,1,3]] $ code
The $ [[15,1,3]] $ triorthogonal code implements transversal $ T $. Since it is a CSS code, two blocks will also have a transversal $ CNOT $ gate. To get a universal gate set all that is required is ...
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Resources on the energy consumption of IBM quantum computers?
I am seeking information regarding the energy consumption of IBM Quantum Computers, specifically inquiring about the energy requirements associated with individual gate operations.
Could you also ...
glS♦
- 25.7k
6
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Can we obfuscate the identity?
Motivated by Aaronson's call to find simple, verifiable proofs of quantumness, suppose we start off with a random polynomial-length circuit $U$ of, say, Hadamard+CCNOT (Toffoli) or CSWAP (Fredkin) ...
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Smallest qudit error correcting/detecting codes
Consider encoding a qubit into $n$ qubits. It is well known that the smallest error detecting code is in $n=4$ qubits and the smallest error correcting code is in $n=5$ qubits.
Is there a similar ...
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Is amplitude estimation optimal?
Amplitude estimation requires $O(1/\epsilon)$ measurements if we want to estimate an amplitude to absolute precision $\epsilon$. Is this optimal? Why can't we do better than this?
I'm trying to see if ...
glS♦
- 25.7k
6
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How to use Warm-Start QAOA in QisKit to solve non-convex QUBO problem?
I have a non-convex QUBO problem that I'd like to solve by warm-starting QAOA with a solution obtained from a continuous relaxation solution obtained by a classical algorithm. The specifics of the ...
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Is it possible to obtain a closed-form expression of the diamond distance between two single-qubit channels?
I would like to compute the diamond norm of the difference of two single-qubit channels $\Phi_1$ and $\Phi_2$. This difference is equal to, for any $2\times2$ complex matrix $\rho$:
$$\...
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Why is combined amplitude and phase damping considered sufficient for noise modeling?
In QECC literature, I often come across the "combined amplitude and phase damping channel" as being representative of a realistic noise model which makes sense (as amplitude damping and de-...
glS♦
- 25.7k
6
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1
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423
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State of the art decoding algorithms for surface code
I am interested to know what are the "most promising" decoder algorithms that are used in surface code today.
Of course, different criteria can tell what we expect from a good decoder. In ...
CommunityBot
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6
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322
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Verification of local unitary equivalence between two pure states
This might be a non-trivial and hard problem. I've been thinking about this for days but couldn't find a good answer, so I hope any of you could give me a good answer/intuition for me to move forward.
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6
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Quantum State Tomography Implementation in IBMQ
I am working to understand quantum state tomography, specifically using the algorithm presented in PRL 108, 070502. This paper is referenced in IBMQ implementations of QST, both in old deprecated ...
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Is No Free Lunch Theorem generalizable to Quantum Computation?
The "No Free Lunch Theorem" says: that when averaged across all possible problems, any two strategies have equivalent performance. However it uses Bayesian reasoning to arrive at this ...
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