Simulating a quantum heat engine on transmon qubits

We devise a scheme to simulate a quantum heat engine using in an array of flux-tunable
transmon qubits. This device provides a one-to-one mapping to a fixed nearest-neighbor coupled,
disordered Bose-Hubbard model, with precision control over transitions between the many
body localized (MBL) phase and the thermal or superfluid phase [Nature 566, 51 (2019)].
Our approach expands on a previous MBL engine proposal [Phys.Rev.B 99, 024203 (2019)],
where the adiabatic strokes involve transitions between the two nondegenerate ground states
and first excited states of the MBL and thermal phases. We expect that this choice of energy
levels reduces the likelihood of excursions to higher levels, especially in the case of the ground
states, serving as a prototype for future investigations into studies of MBL as a thermodynamic resource.