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.

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What is the current qubit reset mechanism on IBM Quantum devices before running a new circuit?

What is the current qubit reset mechanism on IBM Quantum devices before running a new circuit? One could either wait long enough (as much as 2 ms perhaps) in order to ensure that all qubits decay to ...
Radu M.'s user avatar
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Qiskit unitary_simulator seems not to be working

I'm trying to generate the unitary transformation matrix for a very simple circuit (below): ...
Gustavo Mirapalheta's user avatar
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85 views

Problem with SwitchCase in qiskit while using general unitary gate

I am trying to run a circuit using SwithCase Op on one of the 127 qubits backends. My code is the following: ...
Navid Elyasi's user avatar
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17 views

Clarification on the Meaning of Pulse Amplitude in Qiskit Pulse

I'm unclear about the meaning of the pulse amplitude mentioned in the IBM Quantum's Qiskit Pulse documentation. Does the pulse amplitude here refer to the physical amplitude (intensity) of the ...
tare_'s user avatar
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Unitary Matrix for Quantum Random Walk

I am re-working a project which aims to implement a very simple version of a quantum random walk. It actually is a simplified binary random walk on a cyclic graph. The idea is depicted in the ...
zuluratman's user avatar
2 votes
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QPE algorithm to the Hubbard Model

I'm trying to perform the Eigenvalue Estimation algorithm to the Hubbard model with two sites, one spin-up fermion and one spin-down fermion, with Qiskit. Given the Hamiltonian: $\hat{H}=u\sum_{i=1}^N\...
Quantum Lele's user avatar
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1 answer
114 views

Is there any library to create a uniformly random unitary matrix?

Is there any library to create a random special unitary $SU(N)$ that generates from Haar distribution? I understand in PennyLane there is qml.SpecialUnitary ...
Sudhir Kumar's user avatar
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31 views

How to read the code on a partial NOT gate

In the code I am analyzing, I found the following code being: frac = 1/(num+1) qc.u(frac*math.pi,0,0,q[position]) Where I can insert any number integer to the ...
Noodle Master's user avatar
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how to get complete memory stats for a qiskit circuit

I am interested in running several qiskit circuits on multiple GPUs and record their memory usage. My issue is when circuit runs successfully I am unable to get exact amount of memory it took during ...
aneela's user avatar
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procedure for making a probability distribution into a quantum circuit

I found this article on loading a probability distribution into a quantum circuit, the Grover-Rudolph scheme: https://arxiv.org/pdf/quant-ph/0208112.pdf I understand the idea of progressively dividing ...
kerrwe's user avatar
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Reducing the text content inside a custom quantum gate in Qiskit

I have prepared a parameterized custom quantum gate in qiskit by converting a quantum circuit into a gate through QuantumCircuit.to_gate(). However, the text ...
user9043261's user avatar
1 vote
1 answer
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Implementation of classical control of multi-qubits gates multiple times

I am implementing classical control of gates multiple times. There is no issue if the gate is a local gate, such as an $X$ gate. However, it seems that if I append the control multi-qubits gates more ...
JiQing's user avatar
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Is there an "in place" Toffoli gate?

I am trying to implement the multiplication of a scalar in $\mathbb{Z}_2$ and a polynomial in $GF(2^n)$ in Qiskit. One naive method of implementation that I can think of is: ...
Ash Ketchum's user avatar
1 vote
1 answer
77 views

Need help regarding building a custom VQE

I want to write code for a custom Variational Quantum Eigensolver (VQE) capable of computing eigenvalue(s) for non-Hermitian systems, based on this paper. I have formulated a cost function (provided ...
Bravyi's user avatar
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2 votes
1 answer
145 views

Multi-control multi-target gate

I'm using qiskit for simulation. Suppose, I have 6 qubits with indices [0, 1, 2, 3, 4, 5] and I have an operator $U$ of size $4 \times 4$, such that it operates on ...
Марина Лисниченко's user avatar
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67 views

Why there's an issue when a quantum gate is controlled in the same time by 0 on a qubit and 1 or 0 with a classical bit on Qiskit?

I'm doing a project for an internship related to quantum computing and I was trying to do this operation on Qiskit lab: ...
Thomas's user avatar
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mpirun qiskit code doesn't return parallel processing

I am trying to create MPI cluster and run qiskit code on two nodes each with a single GPU installed. Till now I have installed MPI4PY and qiskit-aer-gpu on each node and ran a test script which is do ...
aneela's user avatar
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Expectation value of a given observable computed manually using qiskit.Sampler is different as with qiskit.Estimator

I am trying to calculate the expectation value of a given observable for a certain state $\psi$ using qiskit primitives Sampler (using Sampler requires some further calculations) and Estimator. I ...
ScientiaNatura's user avatar
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1 answer
32 views

Use qiskit-experiments StateTomographyAnalysis on data previously recorded without qiskit

I would like to use the analysis capabilities of qiskit, i.e. StateTomographyAnalysis of qiskit_experiments on data that were previously measured on a system not ...
Anedar's user avatar
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0 answers
42 views

Error: IBMJobFailureError: 'Job failed: Error while executing OpenQASM 3 circuit

I am running my circuit on ibm_osaka backend and it always brings me up this error: IBMJobFailureError: 'Job failed: Error while executing OpenQASM 3 circuit.' Does anyone know what is the cause of ...
Navid Elyasi's user avatar
1 vote
0 answers
49 views

How to use GPU with qiskit as default and then use parallel GPU setup in distributed computing?

I have a GTX 1600 GPU on my computer and I am confused on how to use cuQuantum, Tensorflow or torch etc to enable GPU for qiskit. Further, one of my friends also have a GPU, we want to use both GPUs ...
Syed Shahmir Kazmi's user avatar
1 vote
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Error code 1217, Message: Reduce time between submitting subsequent jobs in a session

I tried running a piece of Qiskit code to minimize a Hamiltonian using QAOA. I tried running the same piece of code that I had used earlier in the IBM Quantum system 'ibm_nairobi' which gave me the ...
Jane's user avatar
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2 votes
1 answer
63 views

Why are keys in the quasidistribution larger than the maximum number allowed by the number of qubits?

I use the IBM' Qiskit Runtime Sampler on a 4 qubits circuit. ...
Maurice Clerc's user avatar
1 vote
1 answer
578 views

No module named 'qiskit.algorithms.linear_solvers'

I am trying to execute HHL algorithm. I referred to the code from https://quantumpedia.uk/quantum-algorithm-4-hhl-algorithm-for-linear-systems-of-equations-40619daec41d. I tried implementing all the ...
quantipai's user avatar
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Interpreting Complex Number Results in Quantum State Discrimination

I have a question regarding the explanation in qiskit pulse. The results are displayed as in the figure, with the following code: ...
tare_'s user avatar
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1 vote
1 answer
30 views

Qiskit ground state solver error

I followed the ground state Eigensolver tutorial in the qiskit document, I got the following error. Is there a solution? My version of qiskit is 0.44.2 and here is the link to that tutorial. https://...
elsh456's user avatar
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Interleaved Randomized Benchmarking experiment with custom PassManager

I have a custom PassManager, which calibrates a few gates in the circuit in the transpiler pass. I want to conduct an Interleaved Randomized Benchmarking experiment ...
Amey Meher's user avatar
4 votes
1 answer
268 views

Qiskit reverse_bits is not equivalent to swapping qubits

For three qubits, I thought swapping the first and third qubit is equivalent to vertically flipping the circuit. However, performing one and then the other in Qiskit returns two different operators, ...
Dylan VanAllen's user avatar
3 votes
0 answers
50 views

Updating qiskit.chemistry.core.Hamiltonian to qiskit-nature Framework

I recently saw a piece of code that computes molecular bond energy with respect to bond length. I am trying to update the code to the newer qiskit framework (I'm running qiskit 0.45.1 and ...
ScientiaNatura's user avatar
1 vote
0 answers
54 views

How to measure different pauli matrices? [duplicate]

I have a system of two qubit interacting and I would like to do 4 measurement, qubit A and qubit B before interaction and qubit A and B after the interaction, now i would like to measure different ...
nicco's user avatar
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Maximum values for frequency and amplitude in Qiskit pulses on IBM devices

Where can I find information about the maximum frequency and maximum amplitude for Qiskit pulses on various IBM quantum computers? Note: it looks like information about frequency range can be found in ...
Radu M.'s user avatar
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2 votes
1 answer
352 views

Running circuits back to back in Qiskit

I am running two circuits on IBMQ back to back like this: ...
Radu M.'s user avatar
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0 votes
0 answers
53 views

QiskitError Cannot convert condition in circuit with multiple classical registers to instruction

I got a qiskit error 'Cannot convert condition in circuit with multiple classical registers to instruction' when I used multiple individual classical registers, such as ...
taketoshi kinoshita's user avatar
0 votes
0 answers
114 views

Adding a phase to a circuit using standard gates

How do I add an arbitrary overall phase to the circuit using standard gates? Yes, I know that the overall phase it irrelevant, yet this is only true until you control the circuit on extra qubits. Yes, ...
mavzolej's user avatar
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Initialize circuit by density matrix (i.e. mixed state) by Cirq, Qiskit, QuTip

I want to do a simulation involving: mid-circuit measurement (i.e. based on the measurement result of some qubits to append further gates on other qubits; e.g., Pauli error correction in entanglement ...
Showhands's user avatar
1 vote
1 answer
58 views

Qiskit result per shot

I want to run a simple circuit with one qubit and a hadamard gate on a Quantum Machine. I want the result of every shot in a list. It works with a simulator and the get_memory function but this ...
EFH's user avatar
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1 vote
1 answer
53 views

How to access collapsed state of your quantum circuit?

I need to be able to see the value of each qubit after measurement. I have a quantum circuit and I am measuring each qubit with measure_all, how do i see their values after this?
kerrwe's user avatar
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0 votes
1 answer
80 views

Equivalent method to `get_counts()` for `Aer_simulator`?

I was working on a quantum circuit and recently switched from using a local AerSimulator to some of the quantum backends provided by IBM. When I used ...
Ash Ketchum's user avatar
0 votes
0 answers
35 views

Initializing an n-qubit quantum circuit with a size 2^n array?

I have a 16 qubit quantum circuit initialized as such: qc.initialize(initial_state, [*range(16)]) where initial_state is a size ...
kerrwe's user avatar
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0 votes
1 answer
45 views

TranspileError occurs when using Simulator Stabilizer

I am writing a small quantum program for supporting polynomial arithmetic, implemented from Space-efficient quantum multiplication of polynomials for binary finite fields with sub-quadratic Toffoli ...
Ash Ketchum's user avatar
1 vote
0 answers
27 views

How to represent the gates and the quibit states in the 'Hello Quantum' iOS game in IBM Quantum Learning graphical simulator

The Hello Quantum ios game developed by IBM has the X, Z, H and CZ gates manipulating a 2 qubit array (im not sure if array is the right word?). I want to know how I can represent the qubit states in ...
chickenj0's user avatar
0 votes
0 answers
12 views

How to convert the normalized units of pulse amplitude od Qiskit Pulse to Hz or something else?

If you have used a Qiskit Pulse then you know that the amlitudes are normalized from 0 to 1. I need to convert this value to Hz or Joules or whatever. This scaling factor also depends on the backend I ...
Meri Harutyunyan's user avatar
0 votes
0 answers
120 views

Qiskit cant run circuit with reset gate with error

In qiskit if i have a reset gate in a circuit. If i want to add noise to the circuit it wont transpile. For example: ...
Narcano's user avatar
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2 votes
0 answers
32 views

Does qiskit make any rounding errors or anything similar, or is it a perfect (but slow) simulation of a quantum computer?

I ran the following circuit to calculate the real part of the Bargmann Invariant of a system of quantum states. The invariant is defined as ...
Srini Thirumalai's user avatar
1 vote
0 answers
61 views

Qiskit experiments state tomography maximum allowed dimension exceeded for pulse gates

I'm trying to run state tomography on a custom pulse gate (currently just a CR(pi/4) pulse) and any attempt to run it on an IBM backend gives a maximum allowed dimension exceeded error. The code runs ...
Max Fawcett's user avatar
1 vote
1 answer
45 views

qiskit statevector ordering issue

I am currently studying Qiskit. I don't understand the two pictures below while studying. When I apply circuit.x(1), the X gate should be applied to the second qubit, resulting in the state |01>. ...
junghyunHa's user avatar
1 vote
0 answers
31 views

Completeness relation of kraus operators not satisfied in Fake backends

With the following code ...
stopper's user avatar
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19 views

Self referencing algorithms for multiplication of binary polynomials

Currently, I am going through the paper "Space-efficient quantum multiplication of polynomials for binary finite fields with sub-quadratic Toffoli gate count" by Iggy van Hoof. Two ...
Ash Ketchum's user avatar
4 votes
1 answer
206 views

Questions on multi-controlled Toffolis and their implementation in Qiskit

Is it possible to decompose an $n$-controlled Toffoli into $O(n)$ CNOTs without extra working qubits? If so, is such an decomposition currently available in Qiskit or any other (preferably Python and ...
mavzolej's user avatar
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1 vote
0 answers
79 views

How can I initialize a classic register in qiskit?

is there a way to initialize a classic register in qiskit? I will go quickly through my problem and then suggest one solution but I am not satisfied with that and ask if there is another solution. ...
Qubii's user avatar
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