Hi all,
due to an odd sequence of events, we'll meet on Tuesday this week.
Alexandre Roulet, visiting from NUS in Singapore, will tell us about
an implementation of a quantum refrigerator (see title and abstract
below).
Originally the Tuesday talk was planned in addition to the regular
meeting on Monday, but overhauling the lecture notes and problem sets
for the thermodynamics course has consumed more time than Philipp, our
scheduled speaker, had planned. So we'll hear from him when things
there are more settled.
Best,
-joe
Title: Quantum Absorption Refrigerator with Trapped Ions
In this work (arXiv:1702.08672), we report on the experimental
realization of a quantum absorption refrigerator, one of the standard
examples of a heat machine, using the modes of trapped ytterbium ions.
The refrigerator is evolving under a trilinear Hamiltonian such that
heat from the work mode is transferred to the hot mode, cooling down
the cold mode in the process. By implementing the refrigerator in the
pulsed (or single-shot) regime, we experimentally cool down the cold
mode faster and to a lower occupation compared to the steady-state
regime. We show theoretically that this feature is enabled by quantum
coherence, as an incoherent evolution of the quantum refrigerator
precludes the device from cooling further than the steady-state
occupation. This is in agreement with previous predictions for
qubit-based refrigerators and highlights the role of quantum coherence
in improving the cooling efficiency of the quantum refrigerator. We
also consider squeezed thermal states and find that they are not a
useful resource for cooling further in the single-shot regime,
comparing them with thermal states of the same average energy.