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.
1,042
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From Qubo Hamiltonian to Ising Hamiltonian
I would like to convert my qubit hamiltonian fom the HeH+ system that I have obtained using Qiskit to an Ising or QUBO model. I have seen multiples examples from QUBO to Qubit Hamiltonian but on the ...
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1answer
36 views
what should we add to complete the program
In the following code, what should replace #Your code here, if we want to create the quantum state $\frac{1}{\sqrt{2}}(|0\rangle - |1\rangle)$?
(Hint: Think about ...
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30 views
How do you debug the following code?
This is code provided by user47787 in response to my previous question: How to use backend.run() with a constant pulse shape in order to get the results of a measurement? When I run the following code,...
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1answer
86 views
Qiskit CNOT-gate matrix mixup?
In the qiskit textbook chapter 1.3.1 "The CNOT-Gate" it says that the matrix representation on the right is the own corresponding to the circuit shown above, with q_0 being the control and ...
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1answer
26 views
How to use backend.run() with a constant pulse shape in order to get the results of a measurement?
I have formed a constant pulse and then I ran a measurement on the pulse. Now, I want to run a job to access the results of the measurement. Attached is a picture of the pulse and measurement. Now, at ...
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35 views
Applying a projector or a general nonunitary gate in the middle of a circuit using qiskit
Is there a way to implement a projector gate in a middle of a circuit?. For instance, assuming I have a Bell state $|00\rangle+|11\rangle$, I'd like to apply a projector on the first qubit onto state $...
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1answer
54 views
How do you change the backend.run() command?
This is code from Chapter 6.1 of the qiskit textbook, which shows a job being run. How would you change the first line of the backend.run() command, the schedules parameter, in order to use it for a ...
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1answer
33 views
Integer factorization using Shor's Alorithm
I have question about Shor's algorithm, from I know it's for factorize an integer and can factorize big number with ease. I using Qiskit to try make a simple factorization program (with local ...
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1answer
37 views
Faster pulse generation in Qiskit
I need to be able to generate very quickly pulse schedules to submit them on quantum chips.
For the moment I am generating instances of QuantumCircuit:
...
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0answers
32 views
Transform Fermionic operators to quantum circuit in qiskit
I am trying to realize a modified version of the UCCSD algorithm, which consists of combining multiple fermionic opeators to form a unitary tranformation U to act ...
2
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1answer
52 views
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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1answer
30 views
Matplotlib graphs are being duplicated each time
Simple UI question. I have installed qiskit according to the instruction and try to implement some basic operations. I have the issue that anything I plot appears twice. I am not sure why this is ...
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1answer
40 views
Pack Header Error when using QAOAProgram [closed]
I want to use QAOAProgram from Qiskit in the following way:
...
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0answers
20 views
How would you measure an X gate with qiskit.pulse.builder.measure?
I am using this link: https://qiskit.org/documentation/stubs/qiskit.pulse.builder.measure.html for reference. How would you use the measure command in order for an X gate to be measured within the ...
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1answer
26 views
What are the runtimes of the different modes of qiskit's mcx?
Qiskit's mcx has four different modes:
'noancilla': Requires 0 ancilla qubits.
'recursion': Requires 1 ancilla qubit if more than 4 controls are used, otherwise 0.
'v-chain': Requires 2 less ancillas ...
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1answer
33 views
I have a questions about the represented values in the chapter “Advanced single bit gates”
I don't understand what are the values of this table at the very end is representing.
My question:
Does decimal values in the table represent Frequency divided by shots?
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52 views
Thoughts in coding large and repetitive/non-repetitive quantum circuits?
Just out of curiosity, are there advances or directions on how to write a program (e.g. in qiskit) for a large number of qubits? Assuming that the number of gates ...
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1answer
27 views
Active space chosen for VQE in qiskit
I encountered a problem when learning from the qiskit tutorial about solving electronic structure problem with VQE. Under the "Running VQE on a Statevector Simulator" part, the code provided ...
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1answer
52 views
How is the state preparation Unitary in initialize selected?
Normally, in order to prepare the Bell state $\frac{1}{\sqrt{2}}(|00\rangle+|11\rangle)$, we can simply make a circuit with a Hadamard gate on $|0\rangle$ followed by a CNOT gate on $|1\rangle$. ...
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1answer
32 views
About qiskit's error mitigation
In qiskit, the error correction using least squares is apparently in qiskit-ignis/qiskit/ignis/mitigation/measurement/filters.py, source code from github and reads:
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1answer
34 views
How to Report an error in the Qiskit Textbook?
In the Qiskit Textbook in Chapter "Introduction to Quantum Computing -> Entangled states -> The CX gate revisited" the following sentence might be wrong:
If we do the CX now, we will ...
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1answer
29 views
How to perform a plot histogram for a circuit?
I have created a circuit and I don't know how to plot a histogram. I tried to plot a histogram but it gives me output for 0000 case only, how to get to know the probability for all of the cases. The ...
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0answers
24 views
Managing memory while running a high depth circuit simulation (amplitude amplification) using Qiskit
I am running an instance of amplitude amplification using Qiskit (v 26) on Google Colab.
The circuit is approximately 17 qubits in space and $O(ck)$ in depth where $k \in \left \{1,2,3....,22 \right \...
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0answers
32 views
How do you verify the output of an X Gate within the Pulse gates framework?
I have found out how to create an X gate for a constant pulse within the Pulse gates framework found on this link: https://qiskit.org/documentation/tutorials/circuits_advanced/05_pulse_gates.html
My ...
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58 views
“503: Server Unavailable. Your server appears to be down. Try restarting it from the hub”. Help
This message is popping continuously for 2 days in my IBM Quantum lab. I have tried logging out and in again, restarting the browser, changing the internet connection, and changing the device but this ...
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1answer
39 views
Trouble when implement a self designed gradient in qiskit
everyone! I have trouble when implement a self-designed gradient to the VQE algorithm. The following code will pop the 'ListOp' object is not callable exception to the last line of the code when ...
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2answers
78 views
How to build a QAOA Ansatz
I saw there is a qiskit package called "QAOAAnsatz" https://qiskit.org/documentation/stubs/qiskit.circuit.library.QAOAAnsatz.html.
But I didn't find out any tutorial related, so I have no ...
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1answer
49 views
Measuring the accuracy of a circuit output?
I have created a circuit and got the output which matches the truth table but, I'm not understanding the measuring the circuit output in terms of the probabilities, power or error.
This is the circuit ...
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2answers
73 views
How do you map an X gate to a constant pulse?
I was wondering how to map an X gate to a constant pulse shape. This https://qiskit.org/documentation/tutorials/circuits_advanced/05_pulse_gates.html is the link that I am working off. It shows an ...
0
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1answer
59 views
Which Qiskit Aer ideal quantum circuit simulator to use when aer_simulator is no longer available?
Some Qiskit tutorials have aer_simulator in the code and I have noticed that this simulator is no longer available.
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2answers
66 views
Ramdon 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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0answers
29 views
How does Qiskit's VQE encode binary digits into a solution from a given Hamiltonian?
So far I have been working with the VQE on different Hamiltonians that happened to have degeneracies, that is there were always at least two different global minima, because the Hamiltonians I was ...
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2answers
60 views
How to convert the output column vector or matrix into bra ket notation using python?
When using qiskit, we normally get the output inform of column vectors or matrix. But is it possible to convert then into bra ket notation using some python code?
Can someone help me with this?
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1answer
47 views
Custom labelling of randomly generated unitaries in Qiskit
I'm writing a program in Qiskit involving the generation of Haar-random unitaries. Is there a way to label each unitary such that the label appears instead of 'unitary' when I draw the circuit?
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1answer
27 views
Qiskit: rounding with get_statevector does not work?
I am trying to follow some tutorials for Qiskit and came to the point where I wanted to get some statevector containing $1/\sqrt{2}$ with the following line of code:
...
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3answers
73 views
How to describe the evolution of a density matrix using the Choi matrix?
How do I apply the Choi matrix on a Density matrix.
Say my process is a Hadamard gate, and my input state is the ground state on 1 qubit (qubit id 0).
$U = H = \dfrac{1}{\sqrt{2}} \begin{bmatrix}1&...
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1answer
36 views
how can we save a model using qiskit_machine_learning?
How can we save a trained model using Qiskit Machine Learning library?
I've built a VQC classification model and once finished, I'd like to save the different models to be loaded later.
There is a <...
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1answer
41 views
Manual measurement error mitigation returning a negative number of counts
I have a simple 2 qubit circuit which I am trying to protect from errors using the measurement error mitigation technique laid out here:
https://qiskit.org/textbook/ch-quantum-hardware/measurement-...
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52 views
Error when computing the self-designed gradient in qiskit
I had question with the way to define a new kind of gradient to improve the performance of VQE. The gradient formula I used consists of multiply energy (measurement result of the Hamiltonian) with the ...
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0answers
46 views
How to solve a linear equation of qubit operators in qiskit?
I am trying to repeat the results from Peng and Kowalski (Eq 11) which solves the analytical form of an equation consisting of powers of the Hamiltonian (moments):
The $K$-th order PDS formalism is ...
0
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1answer
55 views
Get the inverse of a Hermitian operator for measurement in qiskit
I am using qiksit to measure the Hamiltonian H, which isbasically sum of Pauli strings, say something like 2*X^X+0.5*Z^Y. For ...
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2answers
84 views
How to assemble two quantum circuits whose qubit mapping states are different each other?
I uploaded similar question before, but the answer was not I want. I think I should show you in more detail about my question.
I use SABRE algorithm which can do qubit mapping for executing quantum ...
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0answers
49 views
Qiskit equivalent of get_expectation_value() in ProjectQ
Is there a corresponding function that has the same function as function get_expectation_value() in Project Q?
Get the expectation value of qubit_operator w.r.t. the current wave function ...
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5answers
199 views
How can I get the number of measurements where any specific qubit is equal to 0?
Say I am using a 100 qubit quantum computer, but my circuit is such that I am only interested in the output of a particular qubit. So for example I want to know how many outcomes had a result of 0 on ...
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1answer
77 views
What is the correlation between Toffoli and a more generic rotation shown in qiskit textbook
Can someone help me understand the correlation between the 2 diagrams in the qiskit textbook.
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1answer
41 views
How do you create a square pulse in Qiskit?
I am wondering how to create a square pulse in Qiskit. I am working off this Qiskit documentation but still cannot figure out how to create a square pulse.
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1answer
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Trying to connect IBM Quantum to External API
Is it possible to connect a quantum computer to openlibary.org API? How do I find the public IP address to my quantum instance?
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1answer
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How can I simulate the Avg CNOT Error on IBMQ Backends?
I want to know exactly how to estimate the Avg CNOT Error rate for IBMQ Backends?
For instance, I tried to estimate the Avg CNOT Error rate for Belem Backend; I randomly prepared the 00,01,10,11 ...
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0answers
40 views
Where can we find Qiskit exercises solution/answers?
Where can we find Qiskit Exercises solution/answers, is there any website for it?
Or any alternative way to check our answer/solution?
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1answer
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HLL Algorithm results interpretation
I have the following HLL qiskit implementation and really need some help interpreting the results!
CODE ------------------------------
...
