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1500 questions
7
votes
2 answers
Which qiskit backend is faster in execution of the quantum circuit prepared?
I have a quantum circuit of 40 qubits with mutliple gate operations being applied to many of the qubits. Currently I am using qasm simulator which for shots=1 took 10 hour of time. Is there any other backend which can execute my circuit faster or is…
Binshumesh sachan
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7
votes
2 answers
What is the physical intuition behind taking the partial trace of a state?
I want to confirm my understanding of a partial trace.
Essentially, we have a system that $H_a \otimes H_b$. When we trace out system $b$, what we are doing is basically reducing the system down to as if we had just measured system $a$. Essentially,…
snickers_stickers
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7
votes
3 answers
Are entangled and Bell states the same thing?
I am a little confused whether the entangled state and Bell state are the same thing? If they have a bit of contrast, what is the difference between them?
P.Chian
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7
votes
2 answers
How do I get the names of all currently available IBMQ devices?
How do I get the names of all currently available IBMQ devices?
Holger
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7
votes
1 answer
How can a D-Wave style Annealing QPU help sampling?
This question is a follow-up on this one, with the hope of getting more specific clues, and was motivated by this answer by user Rob.
Also please note this posts that handle the topic of QA in much more…
fr_andres
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7
votes
2 answers
How can one argue that the $S$-gate is Clifford while $T$-gate is not?
How can one argue that $S$-gate is Clifford while $T$-gate is not?
heromano
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7
votes
3 answers
Partial Cyclic Permutation with only Toffoli and CNOT gates?
I have been trying to solve this puzzle of constructing this transformation from CNOT and Toffoli gates as mentioned in NC page 193 (Ex 4.27)
Here is what I have done:
First observation is it has 8 rows and columns, so it is showing the table for…
user27286
- 955
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7
votes
1 answer
More efficient implementation of $4$-qubit gate
While working on an error detection algorithm, I stumbled upon the problem of simplifying the following implementation
Here, the $S$ gate is defined by
$$S=\left(
\begin{array}{cc}
\frac{\sqrt{3}}{2} & -\frac{1}{2} e^{\frac{i \pi }{3}} \\
…
QC_QAOA
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7
votes
1 answer
what matrix operations have better known time complexity on a quantum computer?
I'm exploring quantum computers for a semester project. I'm mainly interested in making faster matrix calculations than a regular computer.
I was wondering what arithmetic operations (irrespective of how simple or complex they are) are faster on a…
adiboi
- 71
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7
votes
1 answer
How do we find the stabilizer generators for the three-qubit bit-flip code spanned by $|000\rangle$ and $|111\rangle$?
In Nielsen & Chuang's book "Quantum Computation and Quantum Information" section 10.5.6, page 467 there is the following statement
Consider the familiar three-qubit bit-flip code spanned by the states $|000\rangle$ and $|111\rangle$,…
user27286
- 955
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7
votes
1 answer
Does the no-hiding theorem suggest that quantum information is never destroyed?
According to Wikipedia:
The no-hiding theorem proves that if information is lost from a system via decoherence, then it moves to the subspace of the environment and it cannot remain in the correlation between the system and the environment. This is…
Nick ODell
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7
votes
1 answer
Q# Simulation Behavior
I am attempting to run a series of tests on a Q# program I'm running on the local simulator, but I'm not seeing any way to use >1 shot and collect the results of those shots at once, as in essentially every other quantum language/system I've seen.…
Xavier McCaig
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7
votes
4 answers
What makes representing qubits in a 3D real vector space possible?
Qubits exist in a 2D complex vector space, but we can represent qubits on the Bloch sphere as a 3D real vector space. Mathematically, what makes this possible – why don't we need 4 real dimensions?
Marc Bacvanski
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7
votes
0 answers
Run VQE for parametrized quantum circuit with ancilla qubits
Let's say we have the following circuit (picture and code shown below), and now the $q_0$ is an ancilla qubit. If the system of interest has only two qubits, Is there a way to use only $q_{1,2}$ as my ansatz and plug it into the built-in VQE in…
fagd
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7
votes
2 answers
What kind of boolean functions are faster to compute on qc?
Deutsch-Jozsa algorithm can compute if some function $f : \{0,1\}^n \rightarrow \{0,1\} $ is constant. This goes exponentially faster than on classical computers.
If we consider the set of all boolean functions $f : \{0,1\}^n \rightarrow \{0,1\} $…
user3680510
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