QuantumChemistryQiskit

Tutorials of Quantum Chemistry in Quantum Computers using Qiskit

Fundamentals

Qiskit implements several application modules for different purposes. In this case, since we are going to be interested in Quantum Chemisty we are going to work with the module Qiskit_Nature

Qiskit Nature works with several implementations for typical Quantum Chemistry applications and requires a classic SCF (Self Consistent Field) driver to produce the inputs for the Quantum Computers. Briefly, the main implementations can be divided into:

1. Thermodynamics: To get the vibrational spectrum
2. Vibrational Spectrum Calculation 2.1 UVCC VS 2.2 Analytical VS
3. BOPES Sampler: To explore ground state or excited state potential energy surfaces
4. Excited State Calculations 2.1 ES-ESC (Quantum Eigensolver) 2.2 QEOM (Quantum Equation of Motion Implementation)
5. Ground State Calculations 5.1 Minumum Eigenvalue GSC 5.2 OOVQE 5.3 VQEAdapt

The general structure of Qiskit Nature is splitting any of the applications in: Problem > Solver > Result Or in terms of code

result = solver.solve(problem)

Any of the problems follows this flow:

1. Use of an Electronic Structure Driver (Classic)
2. Gets a group of electronic properties of the molecule
3. Do a base transformation
4. Give back the second quantization operators in terms of femionic operators

Once we have the fermionic operators we just need to transform those into Qbits with a mapper, use qbit operators and go trough any of the quantum algorithms stated above

All the documentation refered to all the details of the methods and algorithms can be found in IBM Qiskit Nature Documentation

Installing Qiskit

As simple as using pip to install it

pip install qiskit
pip install qiskit[nature] # For bash shell
pip install 'qiskit[nature]' # For zsh shell

Also is needed a SCF driver, for convenience can be used PySCF

pip install pyscf