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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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 ...
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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 ...
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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.
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Parallelize estimation of expectation values in Qiskit
Edit
I tried using python multiprocessing library. The result with 8 cores isn't always faster than the original script that uses only one core. How can i improve the algorithm?
Suppose i've a matrix ...
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In Qiskit, no state vector after measure and reset
The code below doesn't work. I am looking for a workaround.
OK, I can save the state vector as numpy array, recreate the whole circuit and initialize it thanks to this array. It works, but any simpler ...
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Passing a book-keeping parameter to Qiskit Ibm Runtime Estimator
I have a Qiskit.QuantumCircuit object circ which prepares the state $| \Psi \rangle$, and a ...
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Access individual qubits of a quantum circuit in qiskit by qubit name
I am very new to quantum computing and only recently started learning Qiskit, so the question may sound a bit silly.
Essentially, when I create a QuantumCircuit ...
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QISKIT Metal Saves Error Generating Python Code
Background
I'm testing out the ability of the Metal GUI to save a simple circuit but it keeps generating code that gives rise to various errors. In the below code for example generates an error show ...
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Is qiskit.pulse.SamplePulse deprecated?
I'm currently following along the book "Learn Quantum Computing with Python and IBM Quantum Experience" by Rodert Loredo and I am at chapter 8 - Generating pulse schedules on hardware. The ...
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What is the difference between shot and iteration of the quantum circuit?
Hi this question is stem from What is meant with "shot" in quantum computation?.
If we just look for the distribution of the result, is there any theoretical difference between method 1 and ...
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How to deal with unused qubits in application specific quantum chips?
Background
I am a complete novice to quantum hardware but am trying to give myself an introduction to Qiskit Metal. I have set myself the challenge of designing a custom quantum chip for the Bernstein-...
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Quantum Annealing on IBMQ using Qiskit-Pulse
Qiskit-Pulse is the analog level control SDK of IBMQ hardware. Is it possible to implement an adiabatic annealing protocol/algorithm on IBMQ hardware using Qiskit-Pulse?
Not asking about QAOA, which I ...
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Is there a way to perform Zero Noise Extrapolation with qiskit without using the runtime service?
Qiskit Runtime is capable of performing Zero Noise Extrapolation (ZNE) using the Estimator primitive. However, due to memory restrictions on IBM cloud, I would like ...
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Frequency of qubits in qiskit simulators
I am trying to study the effect of dynamical decoupling sequences (Hahn Echo and CPMG) using qiskit's qasm_simulator with an added noise model from ...
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Outputing classification probability from the Qiskit VQC
I am new to Qiskit. For the last few days, I have been trying to train my first VQC to do some classification task. Now the VQC is successfully running but it could only output a label whenever I ask ...
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Measuring a single-qubit PauliZ using Qiskit's EstimatorQNN
I am currently working with the EstimatorQNN from Qiskit to construct a Quantum Neural Network using a custom Parametrized Quantum Circuit. But I want to change the ...
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Netlist of the transpiled circuit in Qiskit
I am new to running quantum circuits in Qiskit. In the IBM quantum learning lab, I transpiled a simple 4-qubit quantum circuit using a 7-qubit IBM quantum computer. I received a tranpiled circuit ...
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Increasing memory usage of simulation of quantum circuits in a "for" loop
I have the following code:
...
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Estimating $\pi$ using Quantum Computing - why does it work only in simulator?
I followed the steps from the Qiskit tutorial on YouTube titled "How can I estimate Pi using a quantum computer? - 1 Minute Qiskit"
The code uses Qiskit and apparently works successfully ...
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Are there libraries based on qiskit that can trace over unentangled qubits?
Suppose I have a QuantumCircuit object qc, which contains some unentangled qubits, and a Hamiltonian whose expectation value I ...
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Adding measurement circuits to the singlet state circuit and want to create single circuit
I am trying to add the measurement of Alice and bob's circuit to the singlet circuit. Actually, I am trying to build the e91 protocol. But it is giving me an error like this.
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Simulator able to run SwitchCase in qiskit?
I am trying to run my circuit which is the following on a simulator. However, when I want to execute this on almost all the simulators the following error pops up:
"The control-flow construct '...
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Is there a publicly available compiler for OpenQasm3?
Today (Nov 2023) using OpenQasm3 in the IBM ecosystem can only be done by exporting OpenQasm3 programs to python QuantumCircuit object via qiskit.qasm3.load and qiskit.qasm3.loads or by exporting ...
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Mapping a QUBO onto an observable for use with Qiskit QAOA
Background
I am attempting to understand the post-aqua way that external qiskit libraries are supposed to be used for solving QUBOs. To do so I am trying to work with the toy problem of minimizing $f(...
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Conditioned gates with multiple classical bits
Consider a circuit where you have 6 qubits and apply some gates. Then, you measure qubits 1 , 2 , 3 with results $c_1 , c_2 , c_3$. Next you apply $X^{c_1}$ on the 4-th qubit, $X^{c_1 + c_2}$ on the 5-...
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qiskit QAOA on Aer GPU giving errors
I am trying to run Qiskit QAOA algorithm on using aer simulator and device GPU. But I am not sure how to give this backend in the QAOA algorithm structure.
Here is ...
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Improve accuracy of fake backends while remaining realistic
If I run the code
backend = FakeLima()
nm = NoiseModel.from_backend(backend)
print(nm.__dict__.keys())
I get the following output:
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If_test() - Dynamic Circuits in qiskit
I am trying to run a dynamic circuit by having mid-measurement in my code as follows:
...
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How to explain the output as $|-\rangle$
I am a complete newbie to quantum computing and qiskit. I am trying to implement $H$ gate in Measurement-Based QC architecture based on a paper "Qiskit As a Simulation Platform for
Measurement-...
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Why doesn´t Grover's Algorithm work for my Qiskit circuit?
I built a circuit in Qiskit with two GHZ states. In the beginning, I created the superposition $\sim\bigg(|0000\rangle+|0101\rangle+|1010\rangle+|1111\rangle\bigg)$ with two $H$s, and two $CNOT$s.
Now,...
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Understanding the Role of Qiskit's VQE Code in Light of Pre-calculated Zero-Point Vibrational Energy in Gaussian Files
In the context of quantum computational chemistry, the Qiskit VQE (Variational Quantum Eigensolver) code is often used to calculate the vibrational energies of molecules, including the zero-point ...
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How is a linear combination of pauli operators applied to a quantum circuit in qiskit?
Consider a quantum circuit of 2 qubit:
quantumcircuit = QuantumCircuit(2)
If one wishes to apply a Pauli-X operator to the first qubit, one writes:
...
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How to measure in $\sigma_x$ basis in Qiskit? [duplicate]
As we know, Qiskit can give us the results of our measurements in computational or, better to say, $\sigma_z$ basis. However, I am courageous about measuring the qubit in, for instance, $\sigma_x$ ...
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QISKIT: ValueError: too many subscripts in einsum DensityMatrix()
I am trying to compute the entanglement entropy of a partition of a quantum system on qiskit. To do this, I call the function DensityMatrix(). If I go above 10 sites (e.g. 12), I get an error like:
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What does U mean in pulse schedules for superconducting quantum computers?
What does U channel mean in pulse schedules for superconducting devices? In the image you can see the schedule for a CX gate.
I assume D stands for the drive channels. What does U mean, is it perhaps ...
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How to do modular exponentiation in qiskit with gates?
I understand the following code on why the specific swaps take place, but when I try to replicate it with $N=35$, I get confused.
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How to fix two flip-bit errors in a 3 qubit input
Aware of how a 1-bit flip can be fixed for 3-qubit input by having 2 Ancilla bits, encoding, and using the Toffoli gate to fix the error and decode. How can this idea be extended for a 2-bit flip (...
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Inverse Quantum Fourier Transformation
I have the exercise to implement the Inverse QFT with Qiskit for any number of qubits without the swapping part. I tried to implement something like this for any $n$.
Now I got this code but it doesn'...
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Implementation of Quantum Random Projection
I want to implement quantum version of Random Projection Dimensionality Reduction Technique on a dataset. Even after using the latest version of Qiskit, it gives the following error:
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PulseSchedule jobs not getting submitted on Pulse enabled machines on IBM Quantum
There was a recent migration, referring the below document:
https://qiskit.org/ecosystem/ibm-provider/tutorials/Migration_Guide_from_qiskit-ibmq-provider.html
Before this migration, I was using IBMQ ...
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ZNE for mitigating errors in probability distribution results
Can ZNE be applied to mitigate errors for getting the probability distribution in the computational basis rather than mitigating errors for calculation of expectation values?
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Phase shift on qiskit quantum teleportation simulation
I wonder in Qiskit why the phase shift occurred in my simulation and how I can turn it off.
I posted another question regarding the same simulation here, and while I tried to solve this on my own, I ...
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Retrieving job result attributes in Qiskit
I am trying to optimize a Hamiltonian using QAOA in IBM Qiskit.
I used the following 'minimize' function to get my result. (I am not including the whole code because it will get unnecessarily long).
<...
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What is the mathematical rationale for the decompose() function of qiskit?
The decompose() function decomposes the encapsulated quantum module into sets of elementary quantum gates. But what is the math behind its operation? For example how is a diag[1,1,1,1,1-1,1,1,1,1] ...
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Get parameters of a CU gate for implementing an erroneous CX gate with fidelity = 0.81
Let's say the definition of an erroneous CNOT gate is given as - CNOT is a 2-qubit quantum gate when the control qubit is at state 0, applies identity operation on the target qubit, when the control ...
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I have two Choi matrix I suspect be equivalent. Can I manipulate them?
I am performing a process tomography over a protocol I suspect to be equivalent to the $CS$ gate.
To compare basic operators I usually compute the Choi matrix of the target gate -- which in this case ...
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Is Qiskit's Estimator Primitive running PauliStrings in Parallel?
I am trying to run the following code:
...
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Using "extern" functions in OpenQASM3
I am trying to understand on how to use "extern" functions in OpenQASM3 using Qiskit and the quantum devices from IBM. Judging from the link here (November 2023): https://docs.quantum-...
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