Questions tagged [qiskit]

Quantum Software Development Kit for writing quantum computing experiments, programs, and applications. If appropriate, also use the [programming] tag.

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9 views

How to verify teleportation was successful?

In this circuit (link), q0 is Alice's qubit and q1, q2 are entangled qubits given to Alice ...
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1answer
10 views

Composing teleportation circuit in Qiskit Circuit Composer

I'm trying to create the teleportation circuit in IBM Qiskit Circuit Composer. ...
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1answer
20 views

Which method of executing a multi-control gate is more efficient?

I am interested in executing multi-control gates and I have found two methods to do so as explained below. The first is taken from Nielsen and Chuang (2010) from their Figure 4.10. This method ...
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1answer
27 views

Partial Measurement of Quantum Circuit in Qiskit

I want to do partial measurement of quantum circuit containing two qubits in entangled state. I want to first measure one qubit and record the result. Thereafter, record the measurement of second ...
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33 views

State Vector Output for T$|1\rangle$ in Qiskit differs from manual calculation. Why is this so?

The T Gate is defined as $\begin{bmatrix} 1&0 \\ 0&e^{i\pi/4} \end{bmatrix} = \begin{bmatrix} 1&0 \\ 0&\frac{\sqrt{2}}{2}(1+i) \end{bmatrix}.$ So $\begin{bmatrix} 1&0 \\ 0&\...
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3answers
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How can I obtain transformation matrix of a quantum circuit in the Qiskit?

I need to draw a quantum circuit in Clifford+T library and obtain automatically its transformation matrix. Is there any feature on Qiskit in this case?
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1answer
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Depth for UCC ansatz

I tried to understand the notion of depth vs Trotter step in a uccsd circuit for the vqe algorithm in qiskit (I use an older version, 0.15). When I tried understanding it for a small system like H2, ...
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1answer
75 views

Simulating noise of googles quantum computers

Is there a way to simulate the noise of googles quantum computers using circ? In the same way that any of IBM's computers can be simulated using different backends? ...
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1answer
43 views

Grover's algorithm with matrix_product_state method

I implemented Grover algorithm with matrix_product_state method in qiskit. But I found something strange. I designed the oracle part come out $|1111\rangle$ but, real output was $0011\rangle$. I check ...
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1answer
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How to set overwrite to true with IBMQ?

I'm trying to get setup with https://qiskit.org, but I'm having a problem. I have dug around the internet for a bit and haven't been able to find anything. When I try to run ...
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1answer
23 views

Qiskit BasicAer simulator options

I usually use Qiskit Aer to simulate quantum circuit with several methods such as statevector, ...
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3answers
51 views

Suppress Warnings

I wish to know how to suppress the following warning obtained on qiskit when I try to add two different types of noise to a qubit ...
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1answer
30 views

Qiskit BasicAer & Aer

While I'm simulating grover's algorithm, I found that with BasicAer backend it works well but with Aer it is not. What is the difference between ...
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1answer
27 views

Simulation of Noise in a particular quantum computer

I wish to be able to model a quantum computer with all the noise sources of an IBM quantum computer. For a given set of T1, T2, readout_errors, U2_errors and CNOT errors I want to know how to include ...
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JSONDecodeError with backend.run

I'm trying to follow tutorial on pulse simulation described in qiskit.org. The generated PulseQobj is well executed with AER simulator, but it throws JSONDecodeError when using real backends (ex. ibmq-...
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1answer
29 views

Wavelet Algorithm

Is there any algorithm that implements wavelet (like there is Quantum Fourier Transform). I've tried looking online, but couldn't find any, I wonder if something like this exists. Thank you.
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1answer
35 views

How does VQE performs the measurement on a given Hamiltonian?

I'm trying to understand, given a specific Hamiltonian, for example $H = Z\otimes Z+X\otimes Z$, does the VQE algorithm calculates the expectation value of $Z\otimes Z$ first or does it calculates the ...
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1answer
28 views

Intuition behind the construction of an ansatz circuit

I'm learning about the VQE algorithm. When I looked at the declaration in Qiskit I saw you need to pass an ansatz which prepares the state. I looked at some commonly used ansatz functions, e.g. ...
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1answer
41 views

QPE example on Qiskit

I am learning to do QPE on qiskit. I wanted to choose a simple example to learn, and hence began with the state $|+\rangle$ and operator $X$. I initialized $|+\rangle$ this way: ...
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2answers
62 views

Can I run Cirq on IBMQ?

Google's quantum computer is not yet available for the public. Is it possible to run Cirq on IBM's quantum computers, instead of Qiskit? And if so, how can I do it? Thank you!
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2answers
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How to use VQE function in Qiskit

As part of a project I'm working on, I want to use VQE algorithm to calculate the minimal eigenvalue for given Hamiltonian. I use Qiskit on IBM UI online. The Hamiltonian is given as a sum of tensor ...
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1answer
32 views

Solving mathematical physics equations with Quantum Fourier Transform

Has qiskit already realised(solved) mathematical physics equations? For example, Laplace's equation,Poisson's equation or other? if it is yes, where can i find it?
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1answer
46 views

Odd behavior with Qiskit Pauli operators

I was creating a simple implementation of the Hadamard test when I came across the following, what seems like, strange behavior. Consider the following snippet, which is part of the computating the ...
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1answer
26 views

Syndrome showing unexpected results for the [5,1,3] QEC code in qiskit

I have used the encoding procedure mentioned on page 35 of https://arxiv.org/pdf/quant-ph/9705052.pdf for the [5,1,3] code and then built the circuit for measuring the stabilizers (XZZXI, IXZZX, XIXZZ,...
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1answer
78 views

Error when running HHL algorithm in Qiskit

I tried to solve a simple system of two simultaneous linear equations in with HHL algorithm in Qiskit. In particular the system is $Ax=b$, where $$ A = \begin{pmatrix} 1.5 & 0.5 \\ 0.5 & 1.5 \...
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2answers
44 views

I don't get anything when calling circuit.draw()

I'm following the youtube tutorials for Programming on Quantum Computers and I've completed everything until I reach circuit.draw() since I dont get $|0\rangle$ or ...
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1answer
22 views

Using the qiskit_textbook Package

I've installed the qiskit_textbook package in Anaconda on Windows 10 using ...
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1answer
23 views

How to set 'max_parallel_threads', 'max_parallel_experiments' for BACKEND_OPTIONS in QuantumInstance

In QuantumInstance there are max_parallel_threads, max_parallel_experiments in ...
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1answer
36 views

An effective way to submit all the jobs for VQE/QAOA at a time to an IBMQ machine?

In Qiskit, I am solving a VRP for 5 nodes and it creates 20 variables for a QUBO. It runs in a 65 qubit machines (any machine below that many fails). Now, in such a typical solvers for optimization (...
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63 views

Solving Poisson's equation with Quantum Fourier Transform

I found Quantum Fourier Transform in the Qiskit textbook, but I'm looking specifically for how to solve Poisson's equation with the Quantum Fourier transform. Are there any references that talk about ...
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1answer
49 views

Qiskit transpile with different set of basis gates

I want to use the Qiskit transpile function to decompose an arbitrary unitary matrix/ quantum circuit into a special kind of basis gates. (...
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1answer
30 views

What is the Clifford gates selection probability distribution used in the generation of randomized benchmarking circuits?

I've read that in standard randomized benchmarking implementations the random quantum circuits are generated through random gate selection from a uniformly distributed Clifford set of either 1 or 2-...
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1answer
61 views

Why VQE gives an incorrect ground state energy for a chain of 4 hydrogen atoms?

I am a bit hesitant to ask this very specific question, as I feel other people need not benefit from it. But since I have struggled for a while, and I think I should get some help. So I am using VQE ...
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1answer
52 views

What do the “gate errors rates” mean physically for IBM's quantum computers?

I wish to simulate the gate errors from IBM's various quantum computers. However I am not sure what the gate error rate physically means. An error rate of say 0.01 for a particular means one in every ...
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1answer
35 views

Return outputs with zero counts

I am running a simple 3 qubit circuit which produces the following results: {'000': 5, '001': 3, '010': 10, '100': 5, '101': 7, '110': 7, '111': 4} There are no ...
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What does the error `QiskitError: 'Sum of amplitudes-squared does not equal one.'` mean?

I tried to initialize my circuit qr with the following code: ...
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2answers
22 views

Qiskit implementation of Brassard Amplitude implementaion's Q operator

In Brassard's et al. work, the $Q$ operator is defined as $$ Q =-\mathcal{A}\mathcal{S_0}\mathcal{A}^{-1}\mathcal{S_\chi}$$ I was wondering how is the negative sign at the leftmost side implemented ...
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2answers
91 views

How can i run a quantum circuit with parameterized gates many times on quantum experience?

I want to run a quantum circuit many times on real hardware so that this circuit has some of the parameters that I must change them each time (some of the angles of gates must change each time). how ...
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1answer
61 views

Custom Mixer for QAOA: Error 'Operator' object has no attribute 'primitive_strings'

I like to use as custom Mixer Hamiltonian for solving the TSP using QAOA. The mixer and cost hamiltonians are described here: https://arxiv.org/pdf/1709.03489.pdf - Chapter 5.1. Therefore I need to ...
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1answer
66 views

Qiskit - difference between qasm_simulator and statevector_simulator in terms of memory and speed?

I'm trying to profile qiskit backends and I use randomized_benchmarking provided by qiskit.ignis. Initially I ran a circuit with ...
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0answers
35 views

qasm_simulator generating identical results repeatedly

I wish to run a very simple circuit on the qasm_simulator backend. My circuit is ...
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2answers
42 views

How to realize Su-Schrieffer-Heeger model in Qiskit

This is a very specific question, which I try to implement a simple dimerized tight-binding Hamiltonian on qiskit. The model is one dimensional, and defined as $$ H = \sum_{\langle i,j\rangle} t_{ij} ...
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1answer
31 views

ClassicalRegister gives out just one line instead of two

Why do we have just one line here in c0 and not 2?
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1answer
53 views

Initialising impure density matrices

I wish to initalise the state $\rho=(1-\frac{p}{2})|0\rangle \langle0|+\frac{p}{2}|1\rangle\langle1|$, where p is some measure of decoherence. This is a mixed state. There are some suggestions on here ...
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1answer
59 views

Why do the qasm_simulator runtimes vary significantly for different IBMQ CouplingMap/NoiseModels?

I have been running VQE experiments locally using the qasm_simulator with actual IBMQBackend NoiseModels as shown in the Qiskit Textbook. I have noticed that the ...
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2answers
49 views

How to run VQE experiments on IBMQ Backends?

The VQE.run method only takes a quantum_instance of type QuantumInstance or BaseBackend and ...
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1answer
27 views

Why is the local qasm_simulator significantly slower than the statevector_simulator?

I've been running VQE experiments locally using both the statevector_simulator and qasm_simulator, however I've noticed that the ...
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2answers
52 views

Why is there a significant variation between the exact and VQE energy results?

When running the VQE simulation for $H_2$ over a range of distances as detailed in the Simulating Molecules using VQE section of the Qiskit Textbook, the VQE energy deviation from the exact energy ...

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