Unanswered Questions
69 questions with no upvoted or accepted answers
5
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Add noise_model when using 'ibmq_qasm_simulator' backend and provider.runtime.run() function
I am trying to test some qiskit code that employs readout-error mitigation using the ibmq_qasm_simulator backend and Qiskit Runtime. I am getting the backend as ...
- 51
4
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0
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191
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Apply a single-qubit channel between in between two circuits in Qiskit
Suppose, you have two parts of a circuit in Qiskit, qc1 and qc2 on any number of qubits such that the entire circuit is given by
...
- 959
4
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0
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615
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How is Pauli twirling applied to a noisy gate in practice?
My understanding of Pauli Twirling mainly comes from this paper. Please, correct me if I am wrong in any part of my explanation.
General idea of Pauli twirling
The idea of Pauli Twirling is the ...
glS♦
- 26.9k
4
votes
0
answers
35
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How does it work QasmSimulator with the option "density matrix"?
I am making some simulations on IBM Quantum Lab and as backend I tried to use QasmSimulator(method = "density_matrix") in order to simulate noise. I wanted to know how this method works in ...
4
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0
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131
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Does noise model in qiskit impact the optimized parameters for QAOA?
I have read this paper about the effects of quantum noise on QAOA.
In the conclusion, it says: QAOA is a noise-tolerant algorithm, quantum noise does not change the QAOA quantum circuit parameter ...
- 1,423
4
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0
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111
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What types of noise are there?
I know this does vary to some extent from implementation to implementation, but I'm looking for broad 'classes' of noise.
For example, I know a very common source of noise/error is the environment - ...
- 3,469
4
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0
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480
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Implementing a depolarizing channel for 2 qubits on IBM Q
I am trying to use IBM Q to perform the following depolarizing channel on a state of 2 qubits $\rho=|\psi \rangle \langle \psi |$:
$$\rho \to (1-\lambda)\rho + \frac{\lambda}{4}I$$
This is within ...
- 313
3
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Examples of temperature-dependent quantum channels
I am looking for examples of instances or families of quantum channels that arise out of an interaction of a quantum system with an environment having some temperature. For instance, the generalized ...
- 7,646
3
votes
2
answers
515
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Readout Error in Qiskit: What is a reasonable model?
The Readout Error in Qiskit is described here: https://qiskit.org/documentation/stubs/qiskit.providers.aer.noise.ReadoutError.html
Although it is easy to obtain such an error for 1-qubit for IBMs ...
CommunityBot
- 1
3
votes
1
answer
239
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What are the possible gates that I can use to vary input states before CNOT?
We know that the noise of the $\text{CNOT}$ gate varies depending on the input state before it.
What are the gates that I can put in the place of the 4 identity gates above to change the input state ...
CommunityBot
- 1
3
votes
0
answers
166
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Why are two qubits gates more noisy?
I would like to understand why two qubit gates are generally more noisy.
If I am interested in single qubit gates, I can have an effective modelling as a master equation:
$$\dot{\rho}=\frac{1}{i \...
- 1,962
3
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0
answers
131
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What are reasonable noise/dephasing parameters for QuEST to emulate state-of-the-art quantum computers?
The QuEST code allows for simulation of quantum computers taking dephasing and depolarizing noise into account via one and two qubit dephasing and depolarization. What are realistic parameters for ...
- 17.8k
3
votes
0
answers
88
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What do you specify when you physically apply a unitary?
In the Environment and Quantum Operations in Nielsen and Chuang, section 8.2.2, they say that when you apply a unitary on a state, you expect the output as the just the state transformed by the ...
- 1,641
3
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62
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Does self-induced collapse limit the size of a quantum computer?
This question is related to this question, but I'm specifically interested in self-induced collapse. Suppose that the size of a quantum system alone somehow leads to a projection of the state (a "...
- 17.8k
2
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answers
44
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Is there a standard approach to measure T2 time?
I saw that different ion trap quantum computer manufacturers have given their own T2 (dephasing) times, but it is not clear whether they are obtained by the same test steps.
My question is: Is there a ...
- 14.9k