Thermal State Quantum Simulation of an SU(3) Lattice Gauge Theory Enabled by Motional Mode Ancillae

Quantum simulation remains one of the most promising applications of quantum devices. While many systems of physical interest feature thermal states, efficiently adding the required dissipation to create these states is a largely unsolved problem. In this work, we extend the capabilities of the costly, but effective, ancilla-based state-preparation protocol by replacing the ancillae with the quantized motion of trapped ions, rather than the precious spin qubits primarily controlled on the device. We demonstrate the utility of motional mode ancillae by preparing thermal states at various densities in non-Abelian lattice gauge theories of SU(2) and SU(3) on a trapped-ion quantum computer. We observe the expected phase transition in this 1D theory. This marks the first experimental study of lattice QCD at finite temperature and density on a quantum computer.