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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32 views

How to check accuracy of SABRE algorithm?

I'm studying the qubit mapping algorithm called SABRE. SABRE is an algorithm for solving qubit mapping problem effectively. It uses multiple SWAP gates to execute quantum circuit on real quantum ...
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Coding with Qiskit S2 Ep4 & Ep5 [closed]

Not sure anyone has some advice on the following: S2 Ep4: a) I have issues with installing pyscf, as the error said something on tar file in some folder, and not in some other folder. Causing the ...
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How to construct a controlled $V$ gate in qiskit?

I have come across most of the quantum circuit which contains gate such as controlled $V$ and $V^{\dagger}$ but I dont know how to code it in Qiskit.
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Extract the Crosstalk noise of a circuit in Qiskit

I'm new to Quantum Computing. How to extract the cross-talk noise of a quantum circuit using qiskit? Can someone provide an example code for this?
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Are job IDs unique across backends?

Are job IDs unique across backends, or is it possible that two jobs on two different backends have the same job ID? I'd like to use the job ID as primary key in a database. Thanks in advance!
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How to get measurement result on Qiskit

I want to get measurement result from my circuit output, like '00', '01', '10', or '11' because want to process it further classically. Any suggestion? We can see the highest probability '01'. How I ...
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Why qiskit transpiler makes different results everytime? (Non-deterministic)

I tried to do qubit mapping called 'SABRE' and execute transpiled quantum circuit. I use FakeTokyo backend which has some noise because it is mock version of IBMQ 20-Tokyo. I know using this backend ...
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1answer
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IBMQ.load_account() is failing

When I try IBMQ.load_account or IBMQ.delete_account gives an error in the ubuntu machine and the error is, ...
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Issues in calculating exact runtime on ibmq_16_melbourne

I am working on calculating the exact runtime of a quantum circuit on the ibmq_16_melbourne device. I am using the API ...
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Grover's algorithm outputting random/incorrect results

I am sorry if this question is trivial, I am relatively new to QC. Here is my grover's circuit, as you can see it is displaying that it has a 100% probability of measuring 100 however when placed ...
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Implementation of the Phase Estimation algorithm

I've been working on implementing quantum phase estimation in Qiskit for a $2^n \times 2^n$ Hamiltonian as part of my bachelor project, I'm using Trotterization as my Hamiltonian simulation of choice ...
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Cascade/Feedforward quantum circuits

I would like to know if it is possible implement the following situation in Qiskit (either using the simulators or real quantum computers). Consider this illustrative toy example: The arrows ...
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1answer
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Understanding Grover’s Oracle for 3-SAT

First of all I'm very new to the quantum computing world so this might seem trivial to you, but it's a hump I was unable to get over for days now. So I'm talking about the version that Qiskit has ...
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Transpiling with dynamical decoupling sequence

I am testing circuits which contain mid-circuit reset operations, using Qiskit and IBM Quantum hardware. For 2 qubit simulations, I have a reset operation on one of the qubits and would like to test ...
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Is there an efficient way to create entangled states using Qiskit?

I am trying to implement Grover's search using Qiskit. And I would like to create entangled states so I could search for the index of a specific value in a list. For example, if the third element in ...
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62 views

How to find the expectation value of several circuits using Qiskit aqua operator logic?

I am using the method from this SE answer to calculate the expectation value using qiskit aqua operator logic which works well for a single circuit. Here is a simplified code snippet to demonstrate ...
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Transpilation on restricted topology does not yield an equivalent circuit in Qiskit

Here is an MWE: a simple circuit on three qubits with a CNOT acting on qubits 0 and 2. The coupling map prohibits a two-qubit gate between qubits 0 and 2 and so qubit 1 must get involved. ...
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Qiskit: total number of parameters after composing parametrized circuits

I'm trying to use the .compose() method to join two parametrized circuits, specifically TwoLocal instances from the ...
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Are inconsistent results between different VQE runs justified?

I made this post a while ago, where I learned I could use qiskit's VQE to calculate (or approximate) the Transverse Field Ising Hamiltonian and other similar Hamiltonians. After working with my code ...
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1answer
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When will Qiskit Runtime be available to all users?

IBM's Qiskit Runtime was recently made available to a select group of users. Have they announced when it will be available to all users or when they might open it back up to a second round of new ...
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Qiskit: set_frequency workaround in PulseSimulator

I am trying to run exercise 4 from the recent IBM Quantum Challenge using a PulseSimulator since the device used in the challenge is not available for public use. A snippet of what I am trying to run ...
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1answer
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IF statement in OpenQASM2.0 on IBM Quantum Experience — error

I have written the following toy .qasm file, which has some adaptive measurements: ...
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1answer
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How do I identify a VQE job run in real hardware?

I am running a VQEUCCFactory for H2 on a real hardware device. ...
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Qiskit - lesson 3 - with Abe

Coding for Qiskit I watched this video: https://www.youtube.com/watch?v=RrUTwq5jKM4 Using Mac OS Big Sur Using Jupyter 2.0.8 Using Python 3.8 The below code did not work and therefore installed ...
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1answer
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Quantum circuit for the ZZ feature map

Havlicek et al. propose a feature map for embedding $n$-dimensional classical data on $n$ qubits: $U_{\phi(x)}H^{\otimes n}$, where $$ U_{\phi(x)} = \exp (i \sum_{S \subseteq [n]} \phi_S(x) \prod_{i \...
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Transpilation into custom gate set in qiskit

In qiskit, I can transpile a given circuit into a some predefined gate set as follows (just an example) ...
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How to load time-series stock data into quantum amplitude estimation

Now I got some time-series data as showing example below: I have spent a period of time realizing the QAE from qiskit, and I found that the tutorial used uncertainty model to reproduce data, while I ...
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Use one_body_integrals to know which orbitals to freeze in ElectronicStructureProblem

In exercise 5 of the this year's IBM Quantum Challenge, you need to use the FreezeCoreTransformer (along two_qubit_reduction and ...
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1answer
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quantum label classification using qiskit

I am generating points for classification. Some will be above the main diagonal, while others will be below (blue or red). ...
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Superposition of a subset of integers

I am trying to do the superposition of a subset of integers using qiskit. For instance: $|13\rangle + |14\rangle + ... |N\rangle$ (uniform superposition) without the part $|0\rangle + |1\rangle + ... +...
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Guide for Qiskit's Measurement Error Mitigation?

I'm reading about error correction mainly in the Qiskit Measurement error mitigation chapter contains what it seems and easy way to "clean up" the noise obtained in the IBM (or NISQ) devices....
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Qiskit: Get approximate execution time

The IBMQ web interface shows both queue position and an approximate execution time for every pending job (see image below). Is there a way to retrieve this information via Qiskit? I know that ...
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Apply readout error mitigation to mid-circuit measurement

I'm trying to construct a quantum circuit with 3 mid-circuit measurements, here's an example: ...
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1answer
57 views

QPE Circuit test on Quantum Computer ('ibmq_16_melbourne')

After several atempts, I cannot mitigate the error when running the code on a NISQ, via the qiskit library (more specifically on the 'ibmq_16_melbourne'). I've already mapped the connected qubits and ...
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1answer
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How does the pulse.Shiftphase instruction in Qiskit Pulse work? [closed]

I have some questions regarding the mechanism of Qiskit pulse.ShiftPhase instruction: Does it work like a Phase Shift $P(\theta)=\begin{bmatrix} 1 & 0 \\0 &...
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1answer
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(solved(?)) Quantum circuit in a loop increasing qubit ids throughout despite attempts to reset

I have a parameterized circuit attempting to classify a set of features for various samples. I need to reencode the features per sample, but through the epochs, the computations slow down considerably ...
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1answer
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How to map an arbitrary Fermionic operator to Spins (Qubits)?

There are several Tutorials from Qiskit demonstrating the use of PySCF driver. Usually, it takes as input the geometric structure of the molecule -> second quantised-operators -> JW or Parity ...
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What is the kernel used in the IBM Qiskit's source code?

I want to redefine the QSVM code for a different kernel. But what is the kernel actually used in the IBM Qiskit's source code? And where is it defined, exactly. QSVM on Qiskit.
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Decomposition of gate $R_{y}$ into specific basis

How can I decompose gate $R_{y}(\theta)$ into gate $R_{x}(\alpha)$ and gate $R_{z}(\beta)$. And how to perform it on Qiskit, is there any function to do it.
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Is there a way to within a quantum circuit work out if a qubit is in a superposition or not?

Preferably using the gates found in QASM/Qiskit and the qubit stays in the superposition and no measurement is made, i.e. the output of if it is in a superposition or not is a binary answer in another ...
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1answer
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Implementing quDit algorithms in Qiskit using quBit

How do you implement any $d$-dimensional qudit circuit in qiskit using qubits to simulate on an actual quantum computer?
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1answer
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What explains my anomalously scaled up VQE?

I am trying to implement VQE from the Qiskit to obtain the ground state of a very specific Hamiltonian that has been generated via a docplex minimized quadratic ...
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1answer
76 views

Does Qiskit Statevector has actual speed up for Grover Search?

From Qiskit document, the Statevector can be used to specify the oracle of Grover Search. After seeing the source code of the operators, it seems a statevector is converted to a rank-1 projector ...
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Setting initial state in Qiskit unitary simulator

I'm getting started in IBM quantum lab for quantum computing. My task is to put quantum state $|0\rangle$ on the 1st qubit and state $|1\rangle$ on second one. I tried using this method to initialize ...
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210 views

Differentiable Programming of Quantum Computers

Recently, I have tried PennyLane and TensorFlow Quantum. These platforms are said to provide differentiable programming of quantum computers but I can't understand it clearly though. I have searched ...
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118 views

How to create the equivalent of the Qiskit rxx gate in Pennylane?

How can I create the Pennylane equivalent of: from qiskit import QuantumCircuit circ = QuantumCircuit(2, 2) circ.rxx(theta=0.3, qubit1=0, qubit2=1)
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What is the significance of the phase angle? [duplicate]

I've the following circuit which gives an output of 1 with a phase angle of 3π/4. When we measure the circuit all we get is the ...
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2answers
85 views

Qiskit Pulse Notebook

When I downloaded the source code from Qiskit Notebook Accessing Higher Energy States and tried to execute it, the output and graph seem wrong in the step finding the frequency step which leads to the ...
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1answer
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QAOA not returning solution for simple clustering problem

I am following University's of toronto QML course and there's a section where QAOA is applied to cluster a set of vectors by mapping the clustering problem into a Maxcut problem. Unfortunately qiskit'...
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Things that I can compare between QDK and Qiskit

I am planning to write an article which compares QDK and Qiskit Mainly talking about the different interfaces, and difference in running few algorithms What all parameters should I compare and take ...

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