Kalaee Alex Arash Sand, Wacker Andreas, Potts Patrick P
Mathematical Physics and NanoLund, Lund University, Box 118, 221 00 Lund, Sweden.
Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
Phys Rev E. 2021 Jul;104(1):L012103. doi: 10.1103/PhysRevE.104.L012103.
Nanoscale heat engines are subject to large fluctuations which affect their precision. The thermodynamic uncertainty relation (TUR) provides a trade-off between output power, fluctuations, and entropic cost. This trade-off may be overcome by systems exhibiting quantum coherence. This Letter provides a study of the TUR in a prototypical quantum heat engine, the Scovil-Schulz-DuBois maser. Comparison with a classical reference system allows us to determine the effect of quantum coherence on the performance of the heat engine. We identify analytically regions where coherence suppresses fluctuations, implying a quantum advantage, as well as regions where fluctuations are enhanced by coherence. This quantum effect cannot be anticipated from the off-diagonal elements of the density matrix. Because the fluctuations are not encoded in the steady state alone, TUR violations are a consequence of coherence that goes beyond steady-state coherence. While the system violates the conventional TUR, it adheres to a recent formulation of a quantum TUR. We further show that parameters where the engine operates close to the conventional limit are prevalent and TUR violations in the quantum model are not uncommon.
纳米级热机受到大的涨落影响，这会影响其精度。热力学不确定性关系（TUR）给出了输出功率、涨落和熵成本之间的权衡。表现出量子相干性的系统可能会克服这种权衡。本文对典型量子热机——斯科维尔 - 舒尔茨 - 杜波依斯微波激射器中的TUR进行了研究。与经典参考系统的比较使我们能够确定量子相干性对热机性能的影响。我们通过解析确定了相干性抑制涨落的区域，这意味着量子优势，以及涨落因相干性而增强的区域。这种量子效应无法从密度矩阵的非对角元素中预测出来。由于涨落并非仅由稳态编码，TUR的违背是超出稳态相干性的相干性的结果。虽然该系统违背了传统的TUR，但它遵循了最近提出的量子TUR的表述。我们进一步表明，发动机运行接近传统极限的参数很普遍，并且量子模型中的TUR违背并不罕见。
