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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Is the error rate of IBMQ devices full-scale (% FS) or on percentage of reading (% RD)?

The error rates that I found on the calibration files are given in percentage, but I couldn't find whether it is calculated on full-scale (% FS) or on percentage of reading (% RD). If I do $20000$ ...
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1answer
58 views

Visualize full UCC circuit in qiskit

I am experimenting with the UCC module in qiskit nature. From pyscf, I got 1-body and 2-body integrals (I need to use custom integrals) and thus created a mapped ...
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1answer
31 views

Error Model on id gate, is not giving any error

I am trying to play with NoiseModel of qiskit, and I noticed that error on id gate is not giving any error results, while error ...
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31 views

Quantum Teleportation Algorithm Always Ends in State $|0\rangle$

I'm trying to put together a demo using the Quantum Teleportation example provided by qiskit. The quantum circuit runs as intended when it's initialized to the state $|0\rangle$, and the measured ...
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1answer
23 views

Is the blackbox already a reversible operator, or are we the ones that convert it into one?

I've been studying quantum computing for a little while now (I'm still very new to it), and I'm now studying algorithms (Deutsch's and Simon's). But I'm having some trouble understanding what exactly ...
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1answer
168 views

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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37 views

How to get information about 'qubit location' or 'variable of qubit location' in qiskit docs?

I have something problem with using qiskit. I searched several qiskit docs to get 'qubit location' or 'variables' that represent qubit. I searched three documents below. ...
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1answer
49 views

Representing Qubit Operator in Circuit

I am trying to represent a quantum circuit schematically with some operators in QISKIT. I know I can create some operator with Operator() in quantum_info from a ...
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3answers
1k views

Can't draw figures with Qiskit in Visual Studio

I'm using Qiskit in Visual Studio 2019. I want to draw quantum circuits, but it only shows their sizes with text instead of figures. The output on the interactive window is like this. ...
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About the Qiskit draw function

Where does Qiskit put the rendered figure created by circuit.draw(output='mpl')?
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1answer
59 views

How to construct a parameterised UCCSD ansatz?

I want to try the UCC ansatz for problems other than quantum chemistry. For that I want to 'extract' the UCC ansatz (say from Qiskit) and supply it to my own VQE: I need a parameterised circuit where ...
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1answer
31 views

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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1answer
91 views

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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39 views

Retrieve image from Histogram data of Qiskit

I am trying to understand the quantum image processing. Please refer the link- https://qiskit.org/textbook/ch-applications/image-processing-frqi-neqr.html. I am not able to understand how to process ...
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2answers
93 views

Is there a function in qiskit that allows me to insert quantum gates at certain indices of a circuit?

Here's my quantum circuit with mid-circuit measurements: ...
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2answers
84 views

Why aren’t repetition codes used to encode qubits in superposition states?

I just finished reading the section of the qiskit textbook on quantum error correction using repetition codes(https://qiskit.org/textbook/ch-quantum-hardware/error-correction-repetition-code.html) and ...
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633 views

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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1answer
71 views

QUBO defined in Qiskit/DOcplex: how to solve it using Pennylane?

I have a complex Integer Linear Programming model defined in DOcplex/Qiskit representing a combinatorial optimization problem. Using the Qiskit utils, it is possible to covert it to either an Ising ...
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89 views

Given this code fragment, what is the probability that a measurement would result in $|0\rangle$?

Trying to understand below probability how it occured? qc = QuantumCircuit(1) qc.ry(3 * math.pi/4, 0) A. 0.8536 B. 0.5 C. 0.1464 D. 1.0 And the answer is C. But I ...
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36 views

Quantum GAN implementation

Can anyone provide a good link to understand how to implement qgan using pytorch in qiskit. Trying to understand this ( https://qiskit.org/documentation/machine-learning/tutorials/...
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1answer
26 views

combine_results() attribute error

When I tried to execute the below program, The attribute error hits me every time, which is; name 'combine_result' is not defined What is the problem here? Did I miss a module? ...
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1answer
74 views

Quantum SVM with large feature set

I am trying to practice QSVM from the following tutorial Introduction into Quantum Support Vector Machines The author has used 2 feature_dimension with 2 component PCA ...
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1answer
80 views

How does the ZZ Feature Map influence the measurement?

I've been look at this Notebook from qiskit and trying to understand whats happening, but can't quite figure it out. From my understanding, rotations around the Z ...
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1answer
26 views

Kernel ridge regression with qiskit's FeatureMap shows nonlinear patterns outside [0,1] range

I'm implementing a kernel ridge regressor using qiskit's FeatureMap and QuantumKernel to compute the alpha parameters of the solution. If I try to fit my model with non-normalized features I obtain ...
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1answer
43 views

Quantum Image Processing Application

I have been reading about Quantum Wavelet transform and finding some problems. One of its application is that image is given as input and same image is retrieved as output with reduced size(Please ...
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1answer
72 views

Qiskit simulation not taking in the basis gates listed in pass manager

I was trying to simulate some circuits using the QASM simulator via IBM Quantum Computing Lab online. ...
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1answer
53 views

How to construct a Hamiltonian containing Pauli string by qiskit?

There is a Hamiltonian I want to construct by a Python package, which is the following: $$ H = 5.9I + 0.21Z_0 - 6.12 Z_1 - 2.14(X_0X_1 + Y_0Y_1) + 9.6(I-Z_2) - 3.9(X_1X_2 + Y_1Y_2) $$ It is very easy ...
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1answer
24 views

How can I save IBM Quantum API token to local environment?

I have an IBM Quantum account. How can I save the IBM Quantum API token to local environment so that I can access services including real quantum systems, simulators and Qiskit Runtime programs on my ...
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1answer
31 views

How can I retrieve Qiskit Runtime jobs that I have submitted to IBM Quantum?

I have submitted Qiskit Runtime jobs. How can I retrieve the old jobs to check the status and results?
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1answer
32 views

What happens to the elements of the simulated state vector when we set a qubit to $|0\rangle$?

In IBM's Qiskit online simulator, we have the (non-reversible) ability to set a specific qubit to $| 0\rangle$. This is convenient but I'm left confused as to what happens to the elements of the ...
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2answers
71 views

Qubit identities get swapped in IBM Qiskit

Edit: Improved code a bit This is a condensed description of the IBM bug that was a problem here, to make it more clear. The following code compiles to a correct circuit when the measurement is ...
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1answer
37 views

Qiskit Encoding of a Hamiltonian

I am not sure if this is a trivial question and I am just stuck or this is worth posting. I have a Hamiltonian, which is written in terms of Pauli matrices, such as H = 4.5$I$ - 16 $X_1$ - 16 $X_2$ - ...
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1answer
51 views

Which backends implement the if-else operation?

On which backends (Basic, AER, Simulation, IBMQ) is the qiskit.circuit.controlflow.if_else Operation implemented currently? I want to create a circuit depending on qubit states, e.g.: ...
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1answer
68 views

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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49 views

Is it true that $Ry(\pi/2)\sigma_zRy(-\pi/2)=\sigma_x$?

I saw in a qiskit document that said $Ry(\pi/2)\sigma_zRy(-\pi/2)=\sigma_x$ To confirm this I decided to create the matrix representations of these operations and multiply them together to see if I ...
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2answers
130 views

What is the default coupling map for qiskit

When creating a coupling map the parameters can be left empty, but what type of coupling map does this create. In the Qiskit documentation it says By default, the generated coupling has no nodes. ...
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1answer
211 views

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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56 views

How to impliment Projector Control-Not in Qiskit?

I want to impliment Projector Control-Not in Qiskit just like in this , which is a $|0\rangle\langle 0|$ projector found in the paper "Grand Unification of Quantum Algorithm" page 7. Also, ...
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3answers
8k views

How can I implement an n-bit Toffoli gate?

I want to create a Toffoli gate controlled by n qubits, and implement it in QISKit. Can this be done? If so, how?
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2answers
39 views

How to extract a solution to HHL from the full statevector?

I am having a difficult time trying to extract an HHL matrix inversion solution from the full system statevector. I have a 32x32 size matrix A and a 32x1 vector b, and I ran HHL on 13 qubits. HHL ...
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1answer
42 views

'Internal error. Error code 9999' when running job on IBMQ

I'm trying to run a series of circuits in a job and I keep getting this error message which I haven't been able to find the meaning of anywhere in qiskit's documentation, online, etc. The job appears ...
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1answer
31 views

Is it possible for public users to run experiments using Qiskit's surface code?

I'm an undergrad who would like to run some experiments using the surface code. I've been able to use their quantum repetition code (https://qiskit.org/textbook/ch-quantum-hardware/error-correction-...
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1answer
180 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
184 views

Density Matrix of 3 Qubit Quantum Circuit (Qiskit Density Matrix)

If I have a one gate circuit like in the following image: I can calculate the density matrix by following steps: However, I want to do it for the Toffoli gate circuit: and I am confused with the ...
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2answers
25 views

Qiskit's draw method is moves the gates on the qubit wires

Well,it is not very important problem and I actually did what I wanted but I just noticed that when I want to draw circuit, qiskit draw method is not drawing the circuit with the correct order.. I ...
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2answers
159 views

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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1answer
56 views

Bias in the results of superposition measurements on IBMQ Backends, qiskit

Dear people on this forum, I was doing some research, and I created this circuit in qiskit Please bear in mind that I am really new to this field, and I do not retain much knowledge yet. Therefore I ...
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33 views

How does one use the Qiskit CDMKRippleCarryAdder?

How does one use (call from a main program) Qiskit's CDKMRippleCarryAdder in a quantum circuit, or for that matter, any other Qiskit library of a similar nature? ...

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