Unanswered Questions
2,317 questions with no upvoted or accepted answers
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Relation between quantum entanglement and quantum state complexity
Both quantum entanglement and quantum state complexity are important in quantum information processing. They are usually highly correlated, i.e., roughly a state with a higher entanglement corresponds ...
- 1,482
13
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266
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Does the Curry-Howard correspondence have a quantum-specific type system?
In Wikipedia we can read that
the Curry–Howard correspondence is a correspondence between formal proof calculi and type systems for models of computation. In particular, it splits into two ...
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12
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281
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Is HHL still BQP-complete when the matrix entries are only in {0,1}?
I'm studying BQP-completeness proofs of a number of interesting problems of Janzing and Wocjan, and Wocjan and Zhang. Janzing and Wocjan show that estimating entries of matrix powers $(A^m)_{ij}$ with ...
- 12.2k
12
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Active improving of nanodiamond surfaces for NV centers?
This question is related (and complementary) to "Passive improving of nanodiamond surfaces for NV centers?".
Nitrogen-Vacancy centers (NVs) have astonishing quantum properties, which make them ...
glS♦
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11
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203
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Estimate/determine Bures separability probabilities making use of corresponding Hilbert-Schmidt probabilities
For two-qubit states, represented by a $4\times 4$ density matrix, the generic state is described by 15 real parameters. For ease of calculation, it can help to consider restricted families of states, ...
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10
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130
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Are there separable $\rho$ that cannot be decomposed with less than $\operatorname{rank}(\rho)^2$ pure product states?
In What separable $\rho$ only admit separable pure decompositions with more than $\mathrm{rank}(\rho)$ terms?, examples were given of separable states $\rho$ with separable decompositions requiring ...
glS♦
- 25.7k
10
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559
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Can we use quantum phase estimation to learn anything about the dynamics of puzzles like the Rubik's cube?
Introduction
Consider a state $\vert\psi\rangle$ such as below, which is in a superposition of a difference between a Rubik's cube in a solved state and a Rubik's cube in the "superflip" ...
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Entanglement-assisted hashing bound for asymmetric depolarizing channels
I reading the paper EXIT-Chart Aided Quantum Code Design
Improves the Normalised Throughput
of Realistic Quantum Devices, which proposes the use of QTCs in order to do quantum error correction for ...
glS♦
- 25.7k
10
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121
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Strong vs weak simulations and the polynomial hierarchy collapse
(Edited to make the argument and the question more precise)
An argument for quantum computational "supremacy" (specifically in Bremner et al. and the Google paper) assumes that there exists a ...
- 201
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Anti-symmetrization on the lattice
Assume, I'm using a system of qubits to simulate a fermionic system.
If I'm using the second-quantized formalism (e.g. orbitals in quantum chemistry), the anti-symmetric nature of the fermionic wave ...
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10
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213
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Entanglement transfer of spin-entangled triplet-pair states between flying qubits and stationary qubits
The context: We are in the solid state. After a photon absortion by a system with a singlet ground state, the system undergoes the spin-conserving fission of one spin singlet exciton into two spin ...
9
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191
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How can time crystals be useful in qRAM design?
A time crystal is a phase of a matter which is ordered in time, similar to classical crystals which are ordered spatially. In other words, the structure of a time crystal is ever-changing but with ...
- 14.6k
9
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420
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Is there a BQP algorithm for each level of the polynomial hierarchy PH?
This question is inspired by thinking about quantum computing power with respect to games, such as chess/checkers/other toy games. Games fit naturally into the polynomial hierarchy $\mathrm{PH}$; I'm ...
- 12.8k
8
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Can we distill magic states with arbitrary angle $\theta$?
There seems to be numerous work about the distillation protocol of the $T$-magic state
$$
\frac{1}{\sqrt{2}}(|0\rangle+e^{i\pi/4}|1\rangle).
$$
Similarly, I am wondering if it is possible to distill a ...
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8
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Can you programatically check whether a given set of gates is universal?
I am wondering if there is an automated way to determine whether a given set of quantum operations is universal.
More precisely given a set of 1 and 2 qubit gates can we write a program to determine ...
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