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Unanswered Questions

573 questions with no upvoted or accepted answers
8 votes
1 answer
410 views

Enforcing a particular layout mapping in Qiskit

I would like to ask how to set a particular layout during transpiling. I guess that the layout can be set by the initial_layout parameter in the transpiler. However,...
7 votes
0 answers
210 views

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 ...
6 votes
0 answers
278 views

Quantum State Tomography Implementation in IBMQ

I am working to understand quantum state tomography, specifically using the algorithm presented in PRL 108, 070502. This paper is referenced in IBMQ implementations of QST, both in old deprecated ...
6 votes
0 answers
132 views

Writing circuits in Qiskit using only Clifford and T gates

Is there a way in Qiskit to write my circuit using only Clifford and T gates (CX, S, H, T and I think also $S^\dagger$ and $T^\dagger$)? With the function compile (with aer simulator) it gives me some ...
6 votes
0 answers
141 views

Bell State 11 not working for parity curve

I am currently writing a script to automate the creation of parity curves for a 2 qubit bell state and then calculate fidelity and proving entanglement from that (inspired by this paper). It was going ...
5 votes
0 answers
271 views

How to get the compiled circuits and measurements from a Qiskit Runtime job

I have not been able to find any way to retrieve the compiled circuits and the measurement counts used for a Qiskit Runtime job. This page describes the various error suppression mechanisms available. ...
5 votes
0 answers
662 views

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 ...
5 votes
0 answers
132 views

Which improvements can we expect in Quantum Error Correction?

According to this article: The surface code is currently the most widely pursued quantum error correction scheme (Emphasis mine). It is also said: However, there are drawbacks to the surface code, ...
5 votes
1 answer
718 views

Two qubit gate decomposition using Qiskit

I am writing some python code to be able to optimise the total error in two qubit gate decomposition. I am using the Qiskit module qiskit.quantum_info.synthesis.two_qubit_decompose My question relates ...
5 votes
0 answers
725 views

OpenFermion to Qiskit

Is there a direct way to go from an object generated in OpenFermion to objects usable in Qiskit? I can't find anything about any plugin. It's not too hard to translate into pyQuil and then to Qiskit ...
5 votes
0 answers
160 views

Results from looped experiments on IBM Q different than individual experiments

I'm experiencing an issue while using Qiskit where the counts from a job return vastly different values when ran in a loop or as an array of circuits as opposed to single experiments when run by ...
5 votes
0 answers
157 views

How can I express controlled unitary operation in QPE of this implementation of HHL?

I have found this implementation of HHL, and I don't understand why the controlled unitary operation is expressed in the form of $\exp(i t_0 A/2)$ and $\exp(i t_0 A/4)$. The rotation of $\pi$ and $\...
4 votes
0 answers
60 views

Evaluating expectation values of operators using StateVector and MPS in Qiskit 1.0

Assume one has a QuantumCircuit object and a list of SparsePauliOp. How do I calculate their expectation values using the MPS ...
4 votes
0 answers
94 views

Quantum Phase Estimation for Chemical Hamiltonian

I am working on implementing QPE for calculating the ground state energy of a small molecule like H2 or HeH+. I've written some code that is getting results within about 10% accuracy, but I'm not ...
4 votes
0 answers
68 views

Failed to load program into HAL component

I'm getting this error message when I execute my qiskit code on one of the available quantum computers of IBM: ...

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