Unanswered Questions
405 questions with no upvoted or accepted answers
15
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0
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679
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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 ...
- 1,502
12
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347
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What is the Generalized Quantum Stein's Lemma and why is it important?
I'm sensing a lot of buzz about potential re-proofs of the Generalized Quantum Stein's Lemma - a generalization of the quantum counterpart to the classical Stein's Lemma, which is of some importance ...
- 14.4k
11
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143
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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♦
- 26.9k
11
votes
0
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207
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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, ...
- 24.8k
10
votes
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110
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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♦
- 26.9k
10
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0
answers
218
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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
votes
0
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430
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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 ...
- 14.4k
8
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0
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153
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Are there any known or obvious practical applications for good solutions to the optimal polynomial intersection problem?
I learned from Aaronson's blog about a recent preprint by Jordan, Shutty, Wootters, (our very own) Zalcman, Schmidhuber, King, Isakov, and Babbush that provides an efficient quantum algorithm to give ...
- 14.4k
8
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0
answers
286
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Five qubits can be entangled in how many ways?
It is well-known that there are two ways to entangle three qubits and nine ways to entangle four qubits.
In page 22 of this paper I found that there are infinitely many ways to entangle five qubits, ...
- 3,494
8
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139
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Query on Reduced Graph States
Reduced graph states are characterized as follows (from page 46 of this paper): Let $A \subseteq V$ be a subset of vertices of a graph $G = (V,E)$ and $B = V\setminus A$ the complement of $A$ in $V$. ...
- 24.8k
8
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0
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202
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Better "In-Place" Amplification of QMA
$\def\braket#1#2{\langle#1|#2\rangle}\def\bra#1{\langle#1|}\def\ket#1{|#1\rangle}$
In MW05 the authors demonstrate so-called "in-place" amplitude amplification for QMA, exhibiting a method for Arthur ...
glS♦
- 26.9k
8
votes
0
answers
262
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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♦
- 26.9k
8
votes
0
answers
100
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Are non-secret-based quantum money mini-schemes susceptable to Jogenfors' "reuse attack?"
Aaronson and Christiano call public-key or private-key quantum mini-schemes $\mathcal M$ secret-based if a mint works by first uniformly generating a secret random classical strings $r$, and then ...
- 14.4k
8
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372
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Requirements for Achieving a Quantum Speedup
We usually talk about the power of a quantum computer by examining the separation between sets of gates that we know we can efficiently simulate on a classical computer (i.e. problems in the class BPP)...
- 2,319
7
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77
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If we could only get two-qubit tomography as an output, what algorithms are possible
According to the circuit model, the output for a quantum computation on $n$ qubits is an $n$-bit string. But what if we instead got a full two qubit tomography for all $n(n-1)$ pairs of qubits?
This ...
- 11.5k