db-qite 0.0.8

Implements Double-Bracket Quantum Imaginary Time Evolution (DB-QITE) in Qiskit

Double-Bracket Quantum Imaginary Time Evolution (DB-QITE)

Implementation of DB-QITE (by Gluza et al) and Ground state by DBI (by Gluza)

This repository implements two recently emerged algorithms for Hamiltonian ground state preparation:

• DB-sorter: Based on DBI algorithm sorts the eigenvalues and eigenvectors and chooses the smallest one
• DB-QITE: Mimics imaginary time evolution by approximating Hamiltonian commutation with |0><0|

Installation

pip install db-qite

Usage

To create a QuantumCircuit

DB-sorter

from db_qite import DB_Sorter

dbq = DB_Sorter(
    hamiltonian = H,         # hamiltonian: `SparsePauliOp`
    time_step = s,           # time step. list or a single value
    trotterization = True,   # whether to approx H, default True
)

circuit = dbq.create_circuit(
    num_steps,               # #iterations
)

DB-QITE

from db_qite import DB_QITE

dbq = DB_QITE(
    hamiltonian = H,         # hamiltonian: `SparsePauliOp`
    initial_state = None,    # initial_state array-like, default None
    time_step = s,           # time step. list or a single value
    trotterization = True,   # whether to approx H, default True
)

circuit = dbq.create_circuit(
    num_steps,               # #iterations
    random_u0,               # boolean. U0 is random or not
)

Run for a range of iterations with plots

DB-sorter

from db_qite import db_sorter_range

runner, results = db_sorter_range(
    hamiltonian=H,
    time_step=.5,       # or a list
    num_steps_range=range(1, 3),
    backend=None, #  or "simulator" or a Qiskit Backend
    estimate_energy=True, # wether to estimate energy or just prepare the state
    shots=1024
)

DB-QITE

from db_qite import db_qite_range

runner, results = db_qite_range(
    hamiltonian=H,
    initial_state=None, # or initial state
    time_step=.5,       # or a list
    random_u0=True,     # or False
    num_steps_range=range(1, 6),
    backend="simulator", #  or None to detect a qiskit backend
    estimate_energy=True, # wether to estimate energy or just prepare the state
    shots=1024
)

Note: if you provide None, or a qiskit backend name or object, it will run on IBM quantum machines. You have to set IBM_QUANTUM_TOKEN environment variable for it