Unanswered Questions
17
votes
0answers
302 views
Explicit Lieb-Robinson Velocity Bounds
Lieb-Robinson bounds describe how effects are propagated through a system due to a local Hamiltonian. They are often described in the form
$$
\left|[A,B(t)]\right|\leq Ce^{vt-l},
$$
where $A$ and $B$ ...
11
votes
2answers
134 views
Why is the efficiency of Ekert 91 Protocol 25%?
In Cabello's paper Quantum key distribution without alternative measurements, the author said "the number of useful random bits shared by Alice and Bob by transmitted qubit, before checking for ...
10
votes
0answers
61 views
Does the quantum coherence in the FMO complex have any significance to quantum computing (on a biological substrate)?
The quantum effects of the FMO complex (photosynthetic light harvesting complex found in green sulfur bacteria) have been well studied as well as the quantum effects in other photosynthetic systems. ...
8
votes
0answers
74 views
Quantum walk with binary tree
I’m trying to grok quantum walks, and would like to create an example that walks a perfect binary tree to find the one and only marked leaf node. Is this possible? If so, suppose the depth of the tree ...
8
votes
0answers
120 views
Time Entangled Quantum Blockchain
This answer cites a paper[$\dagger$] which purposes a quantum blockchain using entanglement in time.
"The weakness is that the research only presents a conceptual design." - QComp2018
How could a ...
8
votes
0answers
112 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 $r^{"}$....
7
votes
0answers
69 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, ...
7
votes
0answers
96 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 ...
7
votes
0answers
82 views
What is the difference between quantum control and quantum optimal control?
In the context of quantum control theory, it is common to see references to both quantum control and quantum optimal control (e.g. 0910.2350 or the guide on qutip quantrum control functions).
...
6
votes
0answers
37 views
Resources for quantum biology
Are there any books, courses, tutorials, etc. for studying quantum biology?
Preferably they provide some introduction/primer on the relevant quantum aspects of the quantum biological systems being ...
6
votes
0answers
35 views
Gradient boosting akin to XGBoost using a quantum device
I am currently trying to implement a boosting algorithm akin to XGBoost with a quantum device. The reason is that I want to make use of a quantum device to train weak classifiers. However, as far as I ...
6
votes
0answers
59 views
Devising “structured initial guesses” for random parametrized quantum circuits to avoid getting stuck in a flat plateau
The recent McClean et al. paper Barren plateaus in quantum neural network training landscapes shows that for a wide class of reasonable parameterized quantum circuits, the probability that the ...
6
votes
0answers
49 views
Threshold and practical requirements for initial state preparation?
At the beginning of a quantum computational process we generally want to start in a perfectly known initial state, and evolve from there. This cannot be done perfectly, for fundamental reasons, but I ...
6
votes
0answers
31 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 ...
6
votes
0answers
80 views
Empirical Algorithmics for Near-Term Quantum Computing
In Empirical Algorithmics, researchers aim to understand the performance of algorithms through analyzing their empirical performance. This is quite common in machine learning and optimization. Right ...
