quantlop 0.0.1

High-performance quantum simulator for matrix-free Hamiltonian evolution

Introduction

quantlop is a high-performance simulator for the time evolution of quantum systems whose Hamiltonians can be written as sparse sums of Pauli words. It integrates with PennyLane, so Hamiltonians can be defined with familiar Python operators while the compute-intensive work runs in C++.

Rather than constructing the full Hamiltonian matrix, quantlop applies each Pauli word as a linear operator directly to the state vector. It then uses a Krylov method to numerically approximate the action of the matrix exponential. This matrix-free approach dramatically reduces memory usage and avoids costly dense-matrix operations, making larger simulations more practical.

Installation

The project requires Python 3.11 or later and a C++20-compatible compiler.

pip install quantlop

Usage example

import numpy as np
import pennylane as qp
import quantlop

# set number of qubits
nq = 3

# define Hamiltonian in Pauli basis
op = 0.5 * qp.Z(0) @ qp.Z(1) + 0.2 * qp.Y(0) @ qp.X(2)
ham = quantlop.Hamiltonian.from_pennylane(op, nq)

# prepare initial state vector
psi = np.zeros(2**nq, dtype=complex)
psi[0] = 1.0

# evolve state vector
evolved_psi = quantlop.evolve(ham, psi)

The function quantlop.evolve returns a new state vector corresponding to

\lvert \psi(t) \rangle = e^{-iH}\lvert \psi(0) \rangle.