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.

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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 ...
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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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Why in quatum coin toss, when starting from state $|1\rangle$, we get $|-\rangle$?

I was reading qiskit's text book, there I found that for a Double quantum coin toss, we have negative probability amplitude for $|1\rangle$ state when we starts from $|1\rangle$ state. Link : https://...
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Is there a function in Qiskit to measure tensor products of Pauli operators?

Is there a function in Qiskit similar to this function in Q# which measures strings of Pauli operators applied to different qubits?
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Mitigating Noise and teleportation

Is it possible to use the mitigation process on a teleportation circuit? Sorry, i'm still starting, if someone can get me out of this doubt, I would appreciate it. The circuit I'm trying to make this ...
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Applying quantum operation based on random decision

I want to run a circuit on an IBM quantum computer, and this circuit involves gates that are either applied or not based on a (classical) random decision. As a minimal example, imagine a circuit with ...
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How to run qiskit transpile in parallel in window?

I want to execute qiskit transpile function in parallel. My experiment environment Os is Window and Qiskit version is 0.29.1. I already asked one question here, and I also changed file configuration <...
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Does Qiskit transpiler execute multiple circuits in parallel? [closed]

I have something to ask about Qiskit's transpiler. Before that, please check this document. ...
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Expected outcome of adding two PauliOp

first of all, I would probably report this as a bug if I was confident enough in my QC abilities. As it stands, I've just started out, so I'm phrasing it as a question. From what I can tell, adding ...
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Exacting specific results in running a list of tomography circuit

I run a test on tomography of two circuits like this: ...
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1answer
55 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,...
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1answer
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Is there a faster way to do real-time error mitigation in qiskit?

I'm working on the readout error mitigation on a set of results obtained from different quantum circuits. The method I want to apply is to generate the confusion matrix for each quantum circuit (as ...
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qiskit transpile initial_layout determination

So, I am fairly new to Qiskit, and I've been following Qiskit textbook recently. In the chapter 7, where the QC lab exercises are located, in the first lab when working on the real hardware it is ...
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Is noise the only reason that makes the results of Quantum Support Vector Machine (QSVM) and Classical SVM differ, when we use a large dataset?

When I used and tested out the Quantum Support Vector Machine for just 120 samples of a large dataset (Training - 100 and Testing - 20). Its kernel classification results were quite close to the ...
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How to run a qasm file on IBMQ device?

I can find many qasm examples. How can I run them on different IBMQ devices?
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1answer
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Qiskit: How did they use Haar measure in random_statevector?

I have read this article to understand sampling state vectors from Haar measure: Understanding the Haar Measure. Qiskit uses Haar measure to sample state vectors, but when I looked at the source code ...
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1answer
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Qiskit IBMQ.load_account fails on version 0.20.0

So when trying to load my account I get this error: ...
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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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1answer
37 views

Applying $R^{'\dagger}_{xz}$ in gate teleportation

In figure 4 of the paper Quantum Teleportation is a Universal Computational Primitive, the authors show a circuit for applying a unitary $U$ fault-tolerantly via teleportation. I'll paste the figure ...
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1answer
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Qiskit's QFT not returning the expected state

I'm currently going through the lab problems for the Qiskit course here. I'm trying to finish lab set number 3 on QPE but I can't seem to get the desired output, even from the solution notebook. I'm ...
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Where I can read about protein folding on quantum computers with simple examples?

Where I can read about protein folding on quantum computer (Qiskit will be ideal variant) with simple examples? Thanks
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1answer
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Compute measurement values of observables by Qiskit

Is there a way to get certain measurement results by variational quantum eigensolver in qiskit? More specifically, I want to get measurement results for certain operators, like $\langle a^\dagger_ia_j\...
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1answer
141 views

Can I partially collapse the wavefunction in Qiskit?

I'm trying to do something similar to this question, where I want to partially measure the system before getting the output. In particular, say I have 4 qubits. I want to measure two of them, and then ...
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2answers
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qiskit: IQFT acting on subsystem of reversed-ordered qubits state

I have a state psi as an ndarray of shape (2 ** 3,) s.t. psi[0]= amplitude of 000 ...
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Callback in VQC does not return correct float value for objective function evaluation

The callback for the VQC class is defined as: callback (Optional[Callable[[ndarray, float], None]]) – a reference to a user’s callback function that has two ...
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Hi My Dears, I was working on the Quadratic Equation Solution Technique Using Quantum? [closed]

I was working on the Quadratic Equation Solution Technique Using Quantum ? But it seems to me that there might be no Quantum Benefit for it. If anyone can kindly code this in a cleaver way , Please do ...
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1answer
799 views

Updating qiskit doesn't update qiskit version from Spyder

I installed qiskit using directions at https://qiskit.org/documentation/install.html I also have ...
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1answer
62 views

Error when running a VQE circuit in IBMQ backends

I want to run a VQE circuit of 4 qubits for a simple Hamiltonian with Qiskit. The circuit run smoothly in simulators. However, when I try to implement it on real IBM' quantum computers it gives me the ...
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Can boson sampling be simulated in Qiskit?

In December 2020, there was this claim of quantum advantage/supremacy by a team of USTC using Gaussian boson sampling. Here is the paper and here is an explanatory news article in Nature. To get an ...
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1answer
84 views

How to calculate the Hartree-Fock energy in Qiskit?

I am wondering how to calculate the Hartree-Fock energy efficiently using Qiskit. For one can get the Hartree-Fock state efficiently in Qiskit, however, it seems that it is not so obvious to get the ...
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How is quantum transpilation scaled?

While thinking about a quantum transpiler's working I had a pretty basic doubt. Say that we are trying to transpile an $n$ qubit circuit where $n > 100$. What transpiler does is that it first tries ...
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How to access/ read $\alpha$ and $\beta$ values of a certain qubit in a multi-qubit system in a for loop?

In order to rotate the qubit state I need first to be able to read the values of $\alpha$ and $\beta$ and based on their values I will apply the Q-Gate for rotating the states of the single Qubits in ...
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Qiskit issues with Apple Silicon?

Edit/summary Everything below this first paragraph is my original question posted several days ago and involves a lot of speculating on a problem I knew less about at the time. The purpose of this ...
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What is the input for the interpret of Quantum Variational Regressors?

I'm trying to implement my first variational regressor using qiskit. I would like to understand how the interpret of a CircuitQNN works. I need to define an interpret that works on the amplitudes of a ...
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1answer
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What is difference between qasm_simulator and ibmq_qasm_simulator?

There are many ways how to simulate a quantum circuit on IBM Q. However, in partiuclar I am interested in a difference between qasm_simulator and ...
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2answers
259 views

Qiskit error on get_backend()

Im trying to use IBM quantum machine instead of qiskit aer simulator with the following command: backend = IBMQ.get_backend('ibmq_16_melbourne', 'ibm-q') It's ...
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3answers
74 views

Saving statevector on more than one location in a quantum circuit in Qiskit

So, I'm fairly new to Qiskit, and I've been playing around and following the tutorials from the Qiskit textbook. However, there is one thing I fail to understand/implement: for a quantum circuit with ...
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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 can I obtain the numerical values of the density matrix elements in a state_city plot in qiskit [migrated]

I have run code following the documentation in the qiskit section on Entanglement Verification, up through the steps: [Earlier material from Entanglement Verification, followed by] ...
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What is an example of numbers that when used for a Gaussian pulse, would result in a rotation about the x axis?

For the playing of a Gaussian pulse, what is an example of numbers that could be plugged in for duration, amp, and sigma that would result in the pulse rotating something about the x axis? Here is the ...
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2answers
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Random accuracy using VQC and Iris dataset

Using the same seed (seed_simulator and seed_transpiler) I get different accuracy when running it several times. In Aqua library (from qiskit.aqua.algorithms import VQC) I solved it adding ...
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1answer
89 views

Measuring tensor products of Pauli operators

Is there a neat way to derive and efficiently implement a measurement circuit for tensor products of arbitrary Pauli operators like $XZZXZ$ in Qiskit ? I tried using the ...
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0answers
55 views

What is the right way to teleport qubits on a real quantum computer?

I've been using the teleportation protocol to teleport qubits and then using Qiskit state tomography for reconstructing my qubits. Using this circuit using open qasm I regularly obtain fidelity 0.9. ...
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Save output, wavefunction file and orbital information in Qiskit

I am going through LiH ground state energy calculation. I would like to know how to save the output file in Qiskit as one would do in classical computing using software like Gaussian or Psi4. Also, ...
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1answer
518 views

How to calculate state fidelity in Qiskit?

I have a circuit with different structures, now I'm trying to calculate the fidelity between those with the original one. How do I calculate the fidelity? I want also to initialize the state vector by ...
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How to connect the area of an envelope with angle of rotation? [closed]

How do you connect the area of the envelope of a wave with the angle of rotation about the x axis when performing a rotation with the qiskit pulse program?
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2answers
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How to Implement a noisy identity gate on qiskit?

I can successfully implement the U gate (single qubit) on qiskit, but when I am trying for the identity operation it is not showing any differences with the ideal one .
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Get the probability amplitudes of the 0 and 1 states of a single qubit in Qiskit considering a system of multiple qubits

I am looking for a method to get the values of $\alpha$ and $\beta$ probability amplitudes of each single qubit in a multiple qubit system. Is that possible? As you can see in the image, I have a 4-...

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