Unanswered Questions
854 questions with no upvoted or accepted answers
17
votes
0answers
330 views
Quantum simulation of environment-assisted quantum walks in photosynthetic energy transfer
This question is related to Can the theory of quantum computation assist in the miniaturization of transistors? and Is Quantum Biocomputing ahead of us?
About 10 years ago, several papers discussed ...
12
votes
0answers
240 views
Does higher channel fidelity imply higher entanglement fidelity?
Consider two noisy quantum channels (CPTP maps), $\Phi_1^A$ and $\Phi_2^A$, acting on a system $A$. Suppose that for any pure state $\left|\psi\right>\in \mathcal H_A$,
$$
F\big(\psi, \Phi_1^A(\psi)...
12
votes
0answers
183 views
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 ...
11
votes
0answers
88 views
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 ...
10
votes
0answers
210 views
What are examples of non-oracular versions of famous oracular problems?
Most quantum algorithms proposed, including Deutsch-Jozsa, Simon's, Bernstein-Vazirani etc, involve querying an oracle. If I understand correctly, the speedups depend on the oracle being efficiently ...
10
votes
0answers
152 views
Reference that explains how to read 3d topological diagrams for surface code computations
I like making diagrams to describe computations. For the surface code, an excellent tool is 3d topological diagrams. Here is an example diagram (made by me in SketchUp):
The basic idea is that white ...
10
votes
0answers
237 views
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 ...
10
votes
0answers
162 views
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, ...
9
votes
0answers
111 views
Who was the first to call the phase gates $P(\pi/2)$ and $P(\pi/4)$ the $S$ and $T$ gates, and were they motivated by generators of the modular group?
Within the theory of quantum gates, a common pair of single-qubit phase gates are the $P(\pi/2)=S$ and $P(\pi/4)=T$ gates, with
$$S= \begin{bmatrix} 1 & 0 \\ 0 & i \end{bmatrix},\:T = \begin{...
9
votes
0answers
166 views
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 ...
9
votes
0answers
119 views
Status of hidden shift and hidden subgroup problems
We know that solving a hidden subgroup problem over a non-commutative group is a long standing problem in quantum computing even for groups like $D_{2n}$ (alternatively can be written as $\mathbb{Z}_n ...
9
votes
0answers
95 views
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 ...
9
votes
0answers
164 views
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 ...
8
votes
0answers
136 views
What is stopping FACTORING from being BQP-complete?
Classical complexity theory makes much of the study of so-called intermediate problems - that is, problems that are in $\mathsf{NP}$ but are nonetheless not known to be in $\mathsf{P}$ and further not ...
8
votes
0answers
166 views
Is there a good reason to use T-count minimization for circuits executed on current IBM open quantum systems (real hardware)?
As far as I understood from a series of papers, minimizing the T-count in Clifford+T circuits is essential for fault-tolerant ...
