Thomas George, Johal Ramandeep S
Indian Institute of Science Education and Research Mohali Transit Campus: MGSIPAP Complex, Sector 26, Chandigarh 160019, India.
Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Mar;83(3 Pt 1):031135. doi: 10.1103/PhysRevE.83.031135. Epub 2011 Mar 29.
We study the one-dimensional isotropic Heisenberg model of two spin-1/2 systems as a quantum heat engine. The engine undergoes a four-step Otto cycle where the two adiabatic branches involve changing the external magnetic field at a fixed value of the coupling constant. We find conditions for the engine efficiency to be higher than in the uncoupled model; in particular, we find an upper bound which is tighter than the Carnot bound. A domain of parameter values is pointed out which was not feasible in the interaction-free model. Locally, each spin seems to cause a flow of heat in a direction opposite to the global temperature gradient. This feature is explained by an analysis of the local effective temperature of the spins.
我们将两个自旋为1/2的系统的一维各向同性海森堡模型作为量子热机进行研究。该热机经历一个四步奥托循环，其中两个绝热分支涉及在耦合常数固定值的情况下改变外部磁场。我们找到了使热机效率高于非耦合模型的条件；特别是，我们发现了一个比卡诺界限更严格的上限。指出了一个在无相互作用模型中不可行的参数值域。局部地，每个自旋似乎导致热量沿与全局温度梯度相反的方向流动。通过对自旋的局部有效温度的分析来解释这一特征。
