Quantum-Chemistry-and-Computing-for-the-Curious

Updated, work-in-progress code repository for the book Quantum Chemistry and Computing for the Curious: Illustrated with Python and Qiskit® Code (Packt, 2022), derived from the original Packt Publishing repository: PacktPublishing/Quantum-Chemistry-and-Computing-for-the-Curious.

This repository contains companion Jupyter notebooks of the book that have been successfully run with Qiskit v1.3, Qiskit v2.0, Qiskit v2.1 and the Qiskit Runtime V2 primitives:

• Chapter 3: Chapter_03_Quantum_circuit_model_of_computation_V3.ipynb
• Chapter 4: Chapter_04_Molecular_Hamiltonians_V4.ipynb
• Chapter 5: Chapter_05_Variational_Quantum_Eigensolver_(VQE)_algorithm_V4.ipynb.

We provide a work-in-progress version (V4) of the companion Jupyter notebooks for chapters 4 and 5.

Please refer to the following documentation:

• Migrate to the Qiskit Runtime V2 primitives, https://docs.quantum.ibm.com/migration-guides/v2-primitives
• StatevectorSampler, https://docs.quantum.ibm.com/api/qiskit/qiskit.primitives.StatevectorSampler
• StatevectorEstimator, https://docs.quantum.ibm.com/api/qiskit/qiskit.primitives.StatevectorEstimator

V2 primitives do not perform layout, routing, and translation operations. See the transpilation documentation for instructions to transform circuits.

Qiskit Algorithms is no longer officially supported by IBM. Work is in progress to adapt the whole code base to support V2 primitives and ISA circuits:

• Added V2 and ISA support #197, 🔗https://github.com/qiskit-community/qiskit-algorithms/pull/197
• HamiltonianPhaseEstimation class — Issue #204, 🔗https://github.com/qiskit-community/qiskit-algorithms/issues/204

Warning

Like any other Apache 2 licensed code, you are free to use qiskit_algorithms, qiskit_nature, qiskit/primitives, and qiskit/providers libraries or/and extend them, but please be aware that it is under your own risk.

See disclaimer in readme, 🔗 https://github.com/qiskit-community/qiskit-algorithms?tab=readme-ov-file#qiskit-algorithms

Temporary fix

In this GitHub repository you will find three TAR archive files containing a set of customized files that are needed/used in the Jupyter notebooks for Chapter 4 and Chapter 5.

• qiskit.tar
• qiskit_algorithms.tar
• qiskit_nature.tar

Under your own risk, you can adapt and then run the Copy_V4.ipynb notebook which executes the Copy_V4.py script.

%run Copy_V4

The Copy_V4.py Python script sets a boolean qv1 to True if the version of Qiskit is less than 2.0:

import qiskit
qv = qiskit.__version__
print(f"Qiskit version: {qv}")
qv1 = int(qv[0]) < 2

The shared variable primitive_v2 is set in the file primitive_version.py as follows (customize according to your specific installation path):

#------------------------
# Get site_packages path
#------------------------
import site
sitepackages = site.getsitepackages()

#---------------------------------------------------
# Write primitive_version.py into qiskit_algorithms
#---------------------------------------------------
with open(sitepackages[0] + '/qiskit_algorithms/primitive_version.py', "w") as file:
    # Write a single line to the file
    if qv1:
        file.write("primitive_v2 = False")
    else:
        file.write("primitive_v2 = True")

It then imports it in the code cell that follows Import various algorithms with the following commands:

from qiskit_algorithms.primitive_version import primitive_v2

The shared variable primitive_v2 is imported in a number of Python files, see below examples.

qiskit_algorithms/minimum_eigensolvers/vqe.py

from qiskit_algorithms.primitive_version import primitive_v2

# If version 2 of the Qiskit Runtime primitives
if primitive_v2:
    from qiskit.primitives import BaseEstimatorV2 as BaseEstimator, StatevectorEstimator
    print("\nvqe - Using Qiskit Runtime V2 primitives")
else:
    from qiskit.primitives import BaseEstimatorV1 as BaseEstimator, EstimatorResult
    from qiskit.primitives.estimator import Estimator
    print("\nvqe - Using Qiskit Runtime V1 primitives")