Quantum Simulation of Bosons with the Contracted Quantum Eigensolver

TL;DR

This paper extends the contracted quantum eigensolver (CQE) to simulate many-boson systems on quantum computers, demonstrating its efficiency and accuracy in modeling coupled vibrational modes in molecules.

Contribution

It generalizes the CQE method to bosonic systems by encoding wavefunctions on qubits, enabling efficient simulation of bosonic processes on quantum devices.

Findings

CQE accurately simulates coupled harmonic oscillators.

The method converges well even with noise.

Potential for simulating molecular vibrations on quantum hardware.

Abstract

Quantum computers are promising tools for simulating many-body quantum systems due to their potential scaling advantage over classical computers. While significant effort has been expended on many-fermion systems, here we simulate a model entangled many-boson system with the contracted quantum eigensolver (CQE). We generalize the CQE to many-boson systems by encoding the bosonic wavefunction on qubits. The CQE provides a compact ansatz for the bosonic wave function whose gradient is proportional to the residual of a contracted Schr\"odinger equation. We apply the CQE to a bosonic system, where $N$ quantum harmonic oscillators are coupled through a pairwise quadratic repulsion. The model is relevant to the study of coupled vibrations in molecular systems on quantum devices. Results demonstrate the potential efficiency of the CQE in simulating bosonic processes such as molecular vibrations with good accuracy and convergence even in the presence of noise.