Unanswered Questions
504 questions with no upvoted or accepted answers
17
votes
0answers
612 views
Quantum machine learning after Ewin Tang
Recently, a series of research papers have been released (this, this and this, also this) that provide classical algorithms with the same runtime as quantum machine learning algorithms for the same ...
14
votes
0answers
285 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 ...
11
votes
0answers
588 views
Is there a list of accessible open problems in quantum computing from a theoretical computer science perspective?
(Classical) theoretical computer science (TCS) has a number of outstanding open problems that can easily be instantiated in a manner that is accessible to a wider general public.
For example, ...
10
votes
0answers
147 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 ...
9
votes
0answers
101 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)...
9
votes
0answers
173 views
Quantum Walk: Why the need of adding “tail” nodes to the root?
As stated in the question, I have found in several papers (e.g. 1, 2) that in order to perform a quantum walk on a given tree it is necessary to add some nodes to the root $r$, say $r^{'}$ and $r^{"}$....
8
votes
0answers
137 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 ...
8
votes
0answers
111 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 ...
8
votes
0answers
71 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 ...
7
votes
0answers
44 views
What are the thermodynamic limits of Shor's algorithm
The asymptotic time complexity of Grover's algorithm is the square root of the time of a brute force algorithm. However, according to Perlner and Liu, the thermodynamic behavior (theoretical minimum ...
7
votes
0answers
67 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 ...
7
votes
1answer
141 views
On the distribution of the fidelity of a random product state with an arbitrary many-qubit state
Consider an arbitrary $n$-qubit state $\lvert \psi \rangle$. How much do we understand about the probability distribution of the fidelity of $\lvert \psi \rangle$ with a tensor product $\lvert \alpha \...
7
votes
0answers
72 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 ...
7
votes
0answers
149 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 ...
7
votes
0answers
170 views
Does the GLOA have any advantage over the Solovay-Kitaev algorithm?
The Solvay Kitaev algorithm was discovered long before the Group Leaders Optimization algorithm and it has some nice theoretical properties. As far as I understand, both have exactly the same goals: ...
