Unanswered Questions
16
votes
0answers
246 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 $B$ ...
8
votes
2answers
160 views
Does quantum computing threaten blockchain?
As per Wikipedia, blockchains are a way to maintain "a continuously growing list of records, called blocks, which are linked and secured using cryptography [... and] inherently resistant to ...
7
votes
1answer
70 views
Grover's algorithm: what to input to Oracle?
I am confused about what to input to Oracle in Grover's algorithm.
Don't we need to input what we are looking for and where to find what we are looking for to Oracle, in addition to the ...
7
votes
0answers
56 views
Why does the efficiency of Ekert 91 Protocol is 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 ...
6
votes
0answers
51 views
Visualization of Quantum Circuits when using IBM QISKit
I have followed the installation steps, regarding QISKit working environment. For circuit visualization, I've installed latex as in addition to poppler to convert from PDF to images. Afterwards, I ...
6
votes
0answers
25 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
29 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
86 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 ...
6
votes
0answers
66 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 ...
6
votes
0answers
65 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
1answer
124 views
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)...
5
votes
1answer
80 views
What do “$i$-th basic network”, “quantum multiplexers” and “quantum parallelism” mean in this context? How are they beneficial?
I have been reading the paper A quantum-implementable neural network model (Chen et al., 2017) for a few days now, but failed to understand how exactly their algorithm offers a speedup over the ...
5
votes
0answers
35 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 ...
5
votes
0answers
58 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 ...
4
votes
0answers
20 views
Are bucket-brigate (q)RAM architectures also advantageous in the classical case?
One of the main ideas introduced in Giovannetti et al. 2007
(0708.1879) is the so-called bucket-brigade (q)RAM architecture.
The authors state (first paragraph, second column, first page, in v2) ...
