Quantum thermal state preparation for near-term quantum processors

Preparation of thermal and ground states of many-body quantum systems is a central challenge for near-term quantum processors, needed e.g. as the starting point for many quantum physics experiments or for quantum chemistry applications. I will present recent work [arXiv:2506.21318] on efficient state preparation using engineered system-bath physics. I will explain how the choice of simple time-dependence in the system-bath couplings can be used to enforce detailed balance, dissipatively driving the system toward the thermal or ground state using limited resources. Numerical results for the 2D quantum Ising model demonstrate accurate state preparation, with local observables tightly matching thermal predictions, even close to criticality. The resulting algorithm is particularly suitable for near-term devices, requiring only ancilla reset, local couplings, and Trotterised Hamiltonian evolution.