Unanswered Questions
102 questions with no upvoted or accepted answers
12
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0
answers
134
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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 ...
glS♦
- 26.9k
8
votes
0
answers
295
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What is a gate-level circuit used in the 2022 Jafferis et al. experiment on Sycamore?
A recently published Nature paper of Jafferis et al. describes an experiment with a handful of qubits performed on Google's Sycamore processor to explore the SYK model in the context of AdS/CFT and ...
- 14.4k
8
votes
0
answers
136
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Qubit fidelity of DWAVE device
Since DWAVE quantum device is constructed using superconducting flux qubits, each qubit cannot be produced identically so that the fidelity of the qubit must be different. DWAVE only provides the ...
- 397
8
votes
2
answers
749
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What design considerations set the frequency bounds for superconducting qubits?
Superconducting qubits generally have frequencies within the range of 4 - 8 GHz. What design considerations give the upper and lower bounds for what is a feasible design. I.e, why can't they be higher ...
CommunityBot
- 1
8
votes
0
answers
319
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What are the main obstacles to overcome to build silicon-photonic quantum computers?
In superconducting quantum computers, we use mostly superconducting qubits or trapped ions. However, those systems are quite large because their environment either requires near absolute zero ...
- 17.8k
8
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0
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382
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In D-Wave's universal quantum computer, why does the YY term have to be driven along with the linear X term?
D-Wave has a new prototype annealer that uses a Hamiltonian which, if there was enough qubits and sufficient control, would be able to simulate any universal circuit-based quantum computer with at ...
6
votes
0
answers
144
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Does Randomized Benchmarking characterize decoherence error?
In my understanding, Randomized Benchmarking (RB) generates a sequence of Clifford gates with different lengths and then characterizes the average error. Since RB is not sensitive to SPAM error, it ...
- 1,423
5
votes
0
answers
188
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How do we realise photonic gates?
I am interested in photonic computing, and I am curious how the gates work. I once saw a picture of a photonic CNOT gate that used just mirrors and polarizers. I have not been able to find any ...
glS♦
- 26.9k
5
votes
0
answers
94
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Are single photons necessary for this quantum autoencoder implementation?
The following diagram is from Experimental Realization of a Quantum Autoencoder: The Compression of Qutrits via Machine Learning
How this setup works:
What will be obtained from this set up is the ...
- 437
5
votes
0
answers
82
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Is the theory of decoherence general or specific to the physical implementation?
I’m looking for the theoretical calculations of charge and transmon qubit decoherence specifically, but at a high level I'm wondering how decoherence is approached generally.
I’ve seen explanations ...
- 17.8k
5
votes
0
answers
195
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Quantum Belief Propagation decoding
I have been reading about a family of quantum error correction codes called Quantum Turbo Codes, which are the quantum analog of the well-known classical Turbo codes. This codes were introduced in ...
4
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0
answers
74
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When is a quantum algorithm considered to have a significantly superior performance over another quantum algorithm?
Suppose we have two heuristic quantum algorithms $A$ and $B$ that attempt to solve a certain class of optimization problems. Let's suppose that the benchmarking metric is Time To Solution (TTS), which ...
glS♦
- 26.9k
4
votes
0
answers
185
views
Probability of error in BB84 if Eve is using Breidbart's basis
I'm taking a course on quantum cryptography and I have a homework to calculate probability of error in BB84.
The task says to assume that Eve uses the Breidbart basis with eigenvectors $$|φ_0⟩ = \cos(...
- 2,396
4
votes
0
answers
265
views
What are currently the best reported qubit error rates per gate operation?
Based on some investigation, I have found the best qubit coherence timescales, in superconducting architectures, to be the order of milliseconds.
https://journals.aps.org/prb/abstract/10.1103/PhysRevB....
- 2,396
4
votes
0
answers
46
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How and how much do fabrication defects affect superconducting qubit coherence time?
I used simulations to calculate T1 time of a transmon qubit, but the result is much longer than the lab data. I suspect it was because simulation does not consider fabrication defects. May I ask if ...
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