  Quantum devices are affected by intrinsic and environmental noises. An
in-depth characterization of noise effects is essential for exploiting noisy
quantum computing. To this end, we studied the energy dissipative behavior of a
quantum annealer via experiments and numerical simulations. Our investigation
adopts a recently proposed technique that interpolates between pure quantum
dynamics and pure thermodynamics. Experiments were conducted on a quantum
annealer with an anneal pause function, which inserts a thermal relaxation
period into the annealing schedule by pausing the transverse field, which is a
source of quantum fluctuation. After investigating the special Hamiltonian that
characterizes the quantum thermodynamics of the system, we then observed
enhancement of thermodynamic signature depending on the anneal pause parameter.
The time development of the state vector, observed in the open quantum
simulation, provides rich information for investigating phenomena beyond
energy-gap analysis. We identified a special eigenstate bridges ground states
far-separated in Hilbert space and the transfer probabilities from one ground
state to another. This finding can improve the sampling uniformity by reducing
the sampling bias in finding the classical ground states in the quantum
annealer. Our study does not only characterize the open quantum phenomenon of
the specific Hamiltonian but also demonstrates the usefulness of the method in
investigating noisy quantum devices.
