Abstract

We propose new quantum algorithms for thermal and ground state preparation based on system-bath interactions. These algorithms require only forward evolution under a system-bath Hamiltonian in which the bath is a single reusable ancilla qubit, making them especially well-suited for early fault-tolerant quantum devices. By carefully designing the bath and interaction Hamiltonians, we prove that the fixed point of the dynamics accurately approximates the desired quantum state. Furthermore, we establish theoretical guarantees on the mixing time for several physically relevant models, thereby providing a rigorous justification for the end-to-end efficiency of system-bath interaction models in thermal and ground state preparation.

Personal information

Yongtao is a graduate student in physics at Caltech, advised by John Preskill. His research focuses on the intersection of quantum information, condensed matter physics and computational quantum chemistry. Recently he is working on quantum algorithms for solving quantum chemical problems. He is particularly interested in finding the first killer application of quantum computer in quantum chemistry. He obtained his B.S. in physics at USTC.

Reference

https://arxiv.org/abs/2508.05703