Absorption refrigerators based on Coulomb-coupled single-electron systems

Abstract

We analyze a simple implementation of an absorption refrigerator, a system that requires heat and not work to achieve refrigeration, based on two Coulomb-coupled single-electron systems. We analytically determine the general condition to achieve cooling-by-heating, and we determine the system parameters that simultaneously maximize the cooling power and cooling coefficient of performance (COP) finding that the system displays a particularly simple COP that can reach Carnot's upper limit. We also find that the cooling power can be indirectly determined by measuring a charge current. Analyzing the system as an autonomous Maxwell demon, we find that the highest efficiencies for information creation and consumption can be achieved, and we relate the COP to these efficiencies. Finally, we propose two possible experimental setups based on quantum dots or metallic islands that implement the nontrivial cooling condition. Using realistic parameters, we show that these systems, which resemble existing experimental setups, can develop an observable cooling power.

Boosting the performance of small autonomous refrigerators via common environmental effects

“…They are self-contained configurations, thus avoiding external sources of coherence and control, which may incur in non-trivial thermodynamic costs [20,37] (for a comparison see [38,39]). Proposals for their implementation in the laboratory include quantum-dot models [40,41], a setup with ions in optical cavities [42] or in circuit QED architectures [43,44]. The first experimental realization of a quantum autonomous refrigerator has been recently reported using trapped ions [16].…”

Comparative study of heat-driven and power-driven refrigerators with Coulomb-coupled quantum dots

“…This inequality was also laid out in Ref. [16], to ensure positive heat current streaming from the cold reservoir. We stress that this inequality is only for indicative purpose in the present paper, and as will be shown numerically later, this criterion is not sufficient to guarantee the refrigerator regime beyond the SQME framework.…”

“…with θ( − Γ ) the Heaviside function starting at the boundary Γ = b + U 2 . Engineering this kind of tunneling functions may be realized by making use of an additional quantum dot, or using metallic island as proposed recently [16]. In the following, Γ b = Γ t = Γ will be the energy unit.…”

“…To alleviate these adverse effects, the modeling adopted in Ref. [16], which is otherwise the same as in the present paper, makes a major different hypothesis. Erdman et al do not presume a priori any relation between what they call Γ out/in α (0) and Γ out/in α (1) [72].…”

“…The heat-and power-driven refrigerator properties have already been investigated in Refs. [14,16], though in a T -matrix quantum master equation limited to sequential tunneling processes (SQME). While this approximation is believed to be valid for weak dot-lead tunnel couplings, higher orders as cotunneling events can become quantitatively important [33] even for weak coupling, particularly as shown recently close to the maximum efficiency regime [50].…”