Digital Quantum Simulation of the Spin-Boson Model under Open System Dynamics

TL;DR

This paper demonstrates how to simulate open quantum dynamics of the spin-boson model on IBM's digital quantum hardware, highlighting the importance of accurately implementing unitary evolution and the potential for noise-resilient dissipative simulation.

Contribution

It introduces methods for simulating open quantum systems, specifically the spin-boson model, on real digital quantum computers, including noise considerations and correlation emergence.

Findings

Unitary evolution simulation is crucial for accuracy.

Dissipative dynamics can be simulated with noise resistance.

Correlations between spins can emerge via the oscillator.

Abstract

Digital quantum computers have the potential to simulate complex quantum systems. The spin-boson model is one of such systems, used in disparate physical domains. Importantly, in a number of setups, the spin-boson model is open, i.e. the system is in contact with an external environment which can, for instance, cause the decay of the spin state. Here we study how to simulate such open quantum dynamics in a digital quantum computer, for which we use one of IBM's hardware. We consider in particular how accurate different implementations of the evolution result as a function of the level of noise in the hardware and of the parameters of the open dynamics. For the regimes studied, we show that the key aspect is to simulate the unitary portion of the dynamics, while the dissipative part can lead to a more noise-resistant simulation. We consider both a single spin coupled to a harmonic oscillator, and also two spins coupled to the oscillator. In the latter case, we show that it is possible to simulate the emergence of correlations between the spins via the oscillator.