Questions tagged [qiskit]
Qiskit is an open source SDK for working with quantum computers at the level of pulses, circuits and application modules. If appropriate, also use the [programming] tag. Please include the version of Qiskit you use when using this tag.
476
questions with no upvoted or accepted answers
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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,...
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243
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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 ...
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How can I run a VQE on one of IBMQ's Quantum Computers
I have implemented a VQE based on Qiskit's VQE function and want to run that on an actual quantum computer. My understanding was, that an IBMQ backend can be passed into the function as a Quantum ...
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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 ...
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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 ...
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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. ...
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586
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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 ...
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596
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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 ...
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156
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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 ...
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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 $\...
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Difference between Qiskit and Openfermion two body integrals
I am struggling with understanding the differences between OpenFermion and Qiskit libraries when it comes to Molecular Data, two body integrals.
For example, I am working with the following ...
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Performing Binary Operations on Classical Bits
I am trying to prepare the n-qubits GHZ state using LOCC on Qiskit. The implementation uses the result of some mid-circuit measurements for later operations. I am now using something like
...
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Qiskit QAOA optimization does not work when setting simulation seed in AerSampler
I am using Qiskit's QAOA for optimization and I would like to extract the probabilities distribution obtained in the optimization loop when running the circuit with the optimal parameters set. To do ...
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191
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The error with Estimator primitive due to the qiskit version
The code that I follow is from this tutorial.
But there are some errors due to the version of qiskit on the Estimator primitive
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93
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HHL for the pseudoinverse in Qiskit
The HHL algorithm can be modified to compute the pseudoinverse of $A$ as is shown here and here. Is there anyway to do this in Qiskit without coding the entire thing manually?
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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
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Qiskit: efficient way to create bound circuits?
I am running an optimization problem whose objective function $F(a)$ requires measuring N variational circuits $V_i(a)$ at each evaluation.
So, roughly, I have created N parametric circuits and I do:
<...
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Qiskit NoiseModel.from_backend gives wrong gate error
According to the Qiskit documentation, a gate error is simulated by a thermal relaxation channel followed by a depolarisation channel, where the parameter of the depolarisation channel is adjusted so ...
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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 ...
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How to calculate Quantum Discord for two qubit system using Qutip?
Quantum discord of a bipartite system can be determined as:
$${D_A}({\rho _{AB}}) = I({\rho _{AB}}) - {J_A}({\rho _{AB}}),$$
The subscript of $A$ denotes that the measurement has been performed on the ...
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Predator–prey theory
We have a project where we are supposed to simulate the predator–prey theory in qiskit. Can anyone help or suggest of any ways to start from somewhere because we are kinda lost.
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How to implement a gate that generate a uniform superposition of all permutation of element
I'm looking for a quantum circuit that permits generating a uniform superposition of all possible permutations for example if we have as input $|0123\rangle$ the output will be the uniform ...
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Why does running a pulse schedule for Bell circuit give incorrect counts?
As part of another project I need to be able to run a custom pulse schedule for a bell ciruit and measure the counts. However I am having a problem where running the scheduled circuit is giving counts ...
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What is the most efficient method to update the binary encoded values inside a quantum state?
We're implementing a QML algorithm in which we have to update the value stored inside a quantum state which is strictly unknown to us, by multiplying it with a real number classically stored with us. ...
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Does one measurement affect the following measurement errors in mid-circuit measurement?
Suppose I have a quantum circuit with a few measurements (say $N$) on a single qubit. Before all the measurements, I generated calibration circuits and the 2 by 2 calibration matrix for that qubit of ...
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Why the pulse scheduler produces a different output from the original circuit?
As part of a larger code, I have to convert a quantum circuit into a Pulse scheduler. The problem is that the scheduler output is incompatible with the circuit output. In particular, the difference ...
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Can the ancilla for Qiskit's mcx with mode="recursion" be dirty?
I think their implementation is close to the one from here which does use a dirty ancilla, but I just want to make sure
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4
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83
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Computing specific observable for a Clifford circuit
Given a clifford circuit, how can I simulate it efficiently to get the 2-RDM (reduced density matrix) $D^2=\langle a_i^\dagger a_j^\dagger a_k a_l\rangle$ in the presence of deplorizing error? The ...
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Is it possible to construct a QuantumCircuit object which only shows the 5 qubits and the classical bit where I store the measurement outcome?
I have a 5-qubit circuit on Qiskit, which applies some unitary. Then I have a second circuit which basically measures whether all the qubits are 1, and it does so through a 5-CNOT on an ancilla qubit, ...
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How to design a RF-SQUID qubit by Qiskit Metal?
I am now learning how to use Qiskit Metal to design superconducting circuits. I found that there are only several transmon qubits in the library. Can I design an RF-SQUID qubit by using Qiskit metal?
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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 ...
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Generate certain depth Clifford random circuit by qiskit
To obtain knowledge about the pattern of errors occur in quantum circuits, random Clifford circuits are a good paradigm to use in that these kind of circuits can be efficiently simulated by a ...
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How exactly does the QuantumCircuit.decompose() method work?
From what I can understand from the source code, the circuit is converted into a DAG before the decomposition transpiler is performed onto the DAG circuit.
How does converting to a DAG circuit help us ...
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Extract the Crosstalk noise of a circuit in Qiskit
I'm new to Quantum Computing. How to extract the cross-talk noise of a quantum circuit using qiskit? Can someone provide an example code for this?
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What are the correct eigenvalues to use in controlled rotation in HHL?
I'm studying the HHL algorithm from the qiskit textbook, but I don't understand what $\lambda$ we have to use. If my matrix $A$ has eigenvalues that can be written in a binary representation, then, ...
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How to solve TSP problem with more than 3 nodes in the tutorial of Max-Cut and Traveling Salesman Problem?
I had to try the example of qiskit’s Traveling Salesman Problem with 3 nodes and executing it at IBM backend called simulator_statevector.Can execute and get the result normally.
But when trying to ...
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Transpiler fails after 1000 iterations
I'm transpiling a set of quantum circuits using ibmq_5_yorktown. However, as the number of circuits gets larger, it shows me the following error message:
...
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Implemented QAOA returns wrong result
I try to apply QAOA algorithm to find minimal energy state of the Hamiltonian:
$H_A = \frac{1}{2}\sigma_z^1 + \frac{1}{2}\sigma_z^1\sigma_z^2$
It is expected that with p=2 my variational should ...
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qiskit: Traveling Salesman Problem using QAOA fails for more than 3 cities
I tried to implement the traveling salesman problem (TSP) using QAOA with qiskit. I worked with this qiskit QAOA tutorial and this qiskit minimum eigen optimizer tutorial, where they implement a TSP ...
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Form and effect of the intrinsic Hamiltonian on the IBM machines
I want to understand the form of the intrinsic Hamiltonian of the IBM machines, such as ibmq_16_melbourne, and how this affects the data I get out when waiting ...
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How does batching work in the optimizer loop of the VQC algorithm in Qiskit Aqua?
I've playing around with a binary classification problem with a dataset of size 1000 examples and 5 features. I'm using the VQC algorithm from the Qiskit package the that uses a feature map and a ...
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In Grover, how to implement oracle and amplification using Qiskit?
I found some examples of implementing the oracle when the marked state is $|000\rangle$.
But how can we know what gate we should use inside of the oracle?
Besides, for the part implementation, the ...
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Problem with measurement error mitigation using VQE
I am attempting to mitigate measurement error while running on one of IBM's real devices and am doing so by passing CompleteMeasFitter into ...
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`execute()` hangs and eats memory
Used memory-profiler to check why I get memory spikes in what I though were small circuits. The circuit itself is constructed using ...
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Measuring Coherence Length for T1 and T2 values with IBMQ Experience
So I'm currently working on a little program to measure how long the coherence time of a qubit is. Basically the idea is to initialise a qubit with a X or H gate then stick in a varying amount of ...
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Estimating $\pi$ using Quantum Computing - why does it work only in simulator?
I followed the steps from the Qiskit tutorial on YouTube titled "How can I estimate Pi using a quantum computer? - 1 Minute Qiskit"
The code uses Qiskit and apparently works successfully ...
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qiskit QAOA on Aer GPU giving errors
I am trying to run Qiskit QAOA algorithm on using aer simulator and device GPU. But I am not sure how to give this backend in the QAOA algorithm structure.
Here is ...
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Retrieving job result attributes in Qiskit
I am trying to optimize a Hamiltonian using QAOA in IBM Qiskit.
I used the following 'minimize' function to get my result. (I am not including the whole code because it will get unnecessarily long).
<...
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Quantum error correction circuit from stabilizer codes
I am trying to familiarize myself with QEC codes and their use in quantum communication. Right now, I am trying to implement some more widely known codes in Qiskit. My main problem is I cannot wrap my ...
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4 qubit QFT decomposition in the qiskit textbook
I am reading about the quantum Fourier transform (QFT) in the qiskit textbook, but got stuck at the last part of it which shows a decomposed version of the 4 qubit QFT circuit.
It seems that the ...
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