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.
1,258
questions
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Variational quantum eigensolver in qiskit
I have implemented a hybrid quantum NN on a dataset to perform classification. Now I want to apply quantum PCA to my dataset to find the eigenvalues. After going through a few qiskit tutorials, I ...
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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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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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4
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2answers
66 views
Phase Oracle in Qiskit Solving Satisfiability Problems using Grover's Algorithm Section
In Qiksit Textbook, there is a section on solving satisfiability problems using Grover's Algorithm. For the 3SAT instance
they construct the following phase oracle:
Is there any reasoning behind ...
3
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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 ...
3
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1answer
110 views
Replace Gate with Known Identity in Quantum Circuit
I have a quantum circuit with 3 two-qubits gates XX, YY, and ZZ (as defined in the qiskit circuit library) with arbitrary angles on each gate. I'd like to replace the YY and ZZ gates with XXs. I know ...
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1answer
51 views
How could I choose cost function in Qiskit TwoLayerQNN?
So here is the problem, I've found that in a TwoLayerQNN, the backward gradient is only to minimize the expectation of observable I've chosen. But I'm not going to minimize the predict of the input, ...
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1answer
57 views
Bell state measurement IBM circuit composer
This is my first post in this forum so it is likely that I'll make some rookie mistakes here. In the simple Bell state circuit in IBM circuit composer
we measure the first qubit and for this seed we ...
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0answers
35 views
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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2answers
457 views
Can I initialize only one qubit in a 4-qubit circuit?
I wonder if there's a way we can initialize the quantum state only for part of the qubits in a quantum circuit. Say if I have a quantum circuit defined as ...
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1answer
46 views
Qiskit does not interpret qasm string as 3.0?
I am trying to get my first openqasm3.0 program and I am getting error messages that I cannot interpret.
Here is my program:
...
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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
116 views
Qiskit Implementation of Grover's Algorithm to search a list
Suppose I have a list of numbers from 0 to 32, that is $ [0,1,2....31, 32].$ I want to find a number $n$ in this list such that it satisfies a property, say $n$ is prime. How would I translate this to ...
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49 views
Understanding Qiskit 0.32 's $\texttt{AmplificationProblem()}$ behaviour
This is related to my previous question.
To apply amplitude amplification in Qiskit, one needs to use AmplificationProblem() or ...
2
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0answers
35 views
How to return phase angles as seen in IBMQ composer using qiskit?
I recently transitioned from using the IBMQ composer and am using qiskit in the IBM lab. To start, I wanted to learn how to reproduce the computational basis states, probabilities and phase angles as ...
4
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1answer
38 views
What is the method to create arbitrary controlled circuits in Qiskit?
I am working on an implementation of an algorithm which uses ampitude estimation and amplification as a subroutine but we are not using qiskit but QuEST. QuEST doesn't have any direct method to ...
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1answer
45 views
queueinfo() module in Qiskit
I want to know how to use queueinfo() module in IBM Qiskit. When I type job.QueueInfo(), it says "QueueInfo" is not defined. How to import it? I'm trying to use queueinfo() to know the time ...
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2answers
66 views
Setting the $\texttt{state_preparation}$ for $\texttt{AmplificationProblem()}$ in the scope of Grover's algorithm
I am having trouble setting the state_preparation parameter of AmplificationProblem() from ...
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1answer
35 views
Is it possible to set quantum volume in IBM Quantum simulator?
A quantum volume serves as a metric of a quantum processor quality. So far, IBM Quantum provides processors with quantum volume up to 128. Freely accessbile processors have QV up to 32. A user using ...
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1answer
46 views
For the circuit below, could anyone explain the results I get?
This was sent to qasm_simulator, and the results look like:
It seems qasm has added classical bits but why there are gates on the right side of the line. What do they mean?
Also, what does the result ...
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1answer
37 views
In "from qiskit import *" , how can I check the entire spectrum of imports available [closed]
In some codes, I have seen "from qiskit import QuantumCircuit, aer, execute". Some say "From qiskit import *".
This is python related, I understand, but with respect to Quantum ...
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33 views
I am a beginner and therefore, these three H terms are confusing. "Hemitian", "Hamiltonian", and "Hilbert"
I am a beginner and therefore, these three H terms are confusing. "Hemitian", "Hamiltonian", and "Hilbert". Could someone give proper context and explain these terms . ...
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1answer
52 views
What is the difference between the two entanglement circuits?
For a three qubits system to be in an entanglement(GHZ) state, the circuit can be built as per Qiskit,
Here, the control bit of the second X gate is on q0. what if the control bit is shifted to q1. ...
2
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1answer
92 views
What is the difference between Qiskit Terra, Aer, Ignis and Aqua?
I am going through the Qiskit tutorials and they have an article on each of the above 4. however, As a beginner, I am not very clear. Could anyone share some insights on these?
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1answer
57 views
Hamiltonian of Qiskit QFT is not hermitian
I am trying to generate the Hamiltonian of a quantum Fourier transform by taking the log of the corresponding unitary using qiskit and scipy.
I don't find a hermitian matrix. Why?
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2
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1answer
152 views
Coupling maps in quantum computation
Perhaps a bit naive question from my side, but I could not find any satisfactory answer elsewhere:
What exactly are the coupling maps in quantum computation and, more particularly, how do those maps ...
2
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1answer
84 views
Qiskit - Simpler way to create a Hamiltonian
I am looking for an efficient way to create a Hamiltonian in Qiskit.
Following are my desired input and outputs
input: 'ZZI'
output: Z^Z^I, where Z and I are operators.
Here is how I am doing it ...
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1answer
57 views
Tweak the parameter `p` of QAOA in qiskit
I am solving a QUBO using QAOA. It works flawlessly with default parameters for smaller instances of the problem, but my RAM is saturated when I try to solve a problem of size 15. I suspect this can ...
2
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1answer
80 views
Reading a classical register in OPENQASM
The IBM OpenQASM program below clones a state selected from an orthogonal pair. It seems to work but there is a mystery. I declare the classical register as an array c[1] but when I try to test its ...
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1answer
58 views
Binary classification using a very simple Neural Net with Qiskit and Pennylane
I implemented a simple Neural Net with Pennylane and Qiskit for classifying two half moons: notebook for two half moons (GitHub). It works somehow (not overwhelmingly by any means):
I tried running ...
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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 ...
2
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1answer
54 views
Which observable $M$ provides the Absolute Average of a statevector?
My question should be fairly simple, though I did not find an answer to it here or anywhere else.
I have been working on an algorithm which, similarly to the HHL algorithm, provides a state $|x\rangle$...
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1answer
31 views
Simulating readout errors on aer simulator
I'm trying to simulate quantum experiments using a customized noise model. Here's my code:
...
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28 views
Qiskit- Building an oracle to test on Qiskit's Grover
I want to build an oracle with multiple state solutions.
For example:
For n=4 qubits, I want the state solutions to be 1111, 1101, 1110 and 1100.
So, as you can see, in all solutions, there are two ...
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0answers
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Plots of the result for the qiskit HHL tutorial
Could anyone make explicit the code which gives the two plots at the end of the HHL tutorial. They show the results of the jobs on a real IBM quantum device.
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0answers
45 views
Getting the density matrix of a noisy state in Qiskit
Currently, it seems that qiskit can only compute the density matrix for a pure state. On the other hand, for noisy state, the known way to deal with it is to do sampling, which can induce great cost. ...
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2answers
273 views
Is the SWAP gate a Clifford Gate? How would I express it using the Clifford Gate generators?
By my calculations, it looks like the SWAP gate is a Clifford Gate. See the following table:
I follow the same method as in this paper for showing a gate is a Clifford Gate. I got the above table by ...
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38 views
Using opflow, CircuitStateFn and CircuitSampler, is there any way to submit the expectation values for multiple, distinct states in the same IBMQ job
I am trying to find the expectation of a Hamiltonian w.r.t different states. I am creating my states using CircuitStateFn. Then, I am using ListOp() of CircuitStateFn. But this is giving me an error - ...
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2answers
80 views
How to multiply two vectors (kets) in qiskit?
Hi does anyone know how i could write a program to get the product of something like |1>|0>|0>?
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66 views
Ground state compute issue by qiskit
I use the following code to calculate the ground state for the LiH molecule in an active space. I come across two problems. The first is I found that the Hartree Fock state gave energy that is far ...
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69 views
Evaluating the derivative of a Quantum Circuit
After this post this weekend which got an excellent response, I've been trying to get into the solution that is given by the paper and applying it to my circuit. My original circuit is far bigger and ...
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1answer
66 views
How does qiskit's CircuitQNN calculate the gradients of circuits?
I'm trying to understand how the gradients are calculated for any given circuit using qiskits CircuitQNN and ...
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0answers
27 views
Measuring with a certain probability in Qiskit
I have the following quantum operation on two qubits:
$$ \mathcal{E}(\rho) = p \mathcal{T} \circ \mathcal{U}(\rho) + (1-p) \mathcal{U}(\rho) $$
where $p$ is some probability, $\mathcal{U}$ is some ...
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33 views
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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24 views
In the HHL algorithm, does the controlled unitary depend on the Hermitian matrix coefficients?
In HHL algorithm, does the controlled unitary (Hamiltonian simulation part of Quantum phase estimation) depend on Hermitian matrix coefficients and how?
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2answers
60 views
Create your own n-qubit quantum gate in Qiskit
I need to create the 2-qubit gates that are not supported by Qiskit (Ex: Controlled - F gate). Is there any way to create a class/object and use it as other basic gates?
Example:
...
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0answers
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How to convert code from QISKIT to QuEST using QASM
I have been working on this project which requires a lot of qubits. Originally we have made the whole project in QISKIT as we have been using it for a long time. But the maximum number of qubits that ...
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1answer
47 views
Parallelizing Qiskit not working
I hope this is the right place to ask this kind of question. I'm using the Aer simulator in Qiskit to analyze the state vector of some circuits. My program is very parallelizable, but when I try to ...
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1answer
68 views
Why Grover's search return even distribution with half solution
The image below is the result of finding 4 correct answers from 8 candidates using qiskit. The 4 correct answers I set were 000, 001, 010, 011, but the graph shows the probability is incorrect (the ...
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1answer
92 views
Is there a quantum circuit builder package that allows you to import/export a circuit as a JSON?
I've done a superficial search in each of the qiskit, cirq, and braket open source repositories for such a feature, but can't find any explicit examples of this functionality. I'm wondering if anyone ...
