Qiskit

Developed in Python by IBM, Qiskit is an open-source quantum computing library. Like PennyLane and Snowflurry, it allows you to build, simulate and run quantum circuits.

Installation

1. Load the Qiskit dependencies.

[name@server ~]$ module load StdEnv/2023 gcc python/3.11 symengine/0.11.2

2. Create and activate a Python virtual environment.

[name@server ~]$ virtualenv --no-download --clear ~/ENV && source ~/ENV/bin/activate

3. Install a version of Qiskit.

(ENV) [name@server ~] pip install --no-index --upgrade pip
(ENV) [name@server ~] pip install --no-index qiskit==X.Y.Z  qiskit_aer==X.Y.Z

where X.Y.Z is the version number, for example 1.1.0. To install the most recent version available on our clusters, do not specify a number. Here, we only imported qiskit and qiskit_aer. You can add other Qiskit software with the syntax qiskit_package==X.Y.Z where qiskit_package is the softare name, for example qiskit-finance. To see the wheels that are currently available, see Available Python wheels.

4. Validate the installation.

(ENV)[name@server ~] python -c 'import qiskit'

5. Freeze the environment and its dependencies.

(ENV)[name@server ~] pip freeze --local > ~/qiskit_requirements.txt

Running Qiskit on a cluster

File : script.sh

#!/bin/bash
#SBATCH --account=def-someuser #Modify with your account name
#SBATCH --time=00:15:00        #Modify as needed
#SBATCH --cpus-per-task=1      #Modify as needed
#SBATCH --mem-per-cpu=1G       #Modify as needed

# Load module dependencies.
module load StdEnv/2023 gcc python/3.11 symengine/0.11.2 

# Generate your virtual environment in $SLURM_TMPDIR.                                                                                                         
virtualenv --no-download ${SLURM_TMPDIR}/env                                                                                                                   
source ${SLURM_TMPDIR}/env/bin/activate  

# Install Qiskit and its dependencies.                                                                                                                                                                                                                                                                                    
pip install --no-index --upgrade pip                                                                                                                            
pip install --no-index --requirement ~/qiskit_requirements.txt

# Modify your Qiskit program.                                                                                                                                                                       
python qiskit_example.py

You can then submit your job to the scheduler.

Use case: Bell states

Before you create the first state, the required modules need to be loaded.

   from qiskit_aer import Aer
   from qiskit import QuantumCircuit, transpile
   from qiskit.visualization import plot_histogram

Define the circuit. Apply an Hadamard gate to create a superposition state on the first qubit and a CNOT gate to intricate the first and second qubits.

   circuit = QuantumCircuit(2,2)
   circuit.h(0)
   circuit.cx(0,1)
   circuit.measure([0,1],[0,1])

Specify the simulator you want to use and transpile the circuit. This provides the final number of qubits after having made all the measurements.

   simulator = Aer.get_backend('qasm_simulator')
   compiled_circuit = transpile(circuit, simulator)
   job = simulator.run(compiled_circuit)
   result = job.result()
   counts = result.get_counts()
   print("counts: ", counts)
   {'00': 489, '11': 535}

The results are displayed.

   plot_histogram(counts)

Results of 1000 measurements on the first Bell state