Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S.A.S. Nagar, Manauli P.O. 140306, Punjab, India.
Phys Rev E. 2017 Sep;96(3-1):032110. doi: 10.1103/PhysRevE.96.032110. Epub 2017 Sep 8.
We consider a quasistatic quantum Otto cycle using two effectively two-level systems with degeneracy in the excited state. The systems are coupled through isotropic exchange interaction of strength J>0, in the presence of an external magnetic field B which is varied during the cycle. We prove the positive work condition and show that level degeneracy can act as a thermodynamic resource, so that a larger amount of work can be extracted than in the nondegenerate case, both with and without coupling. We also derive an upper bound for the efficiency of the cycle. This bound is the same as derived for a system of coupled spin-1/2 particles [G. Thomas and R. S. Johal, Phys. Rev. E 83, 031135 (2011)PLEEE81539-375510.1103/PhysRevE.83.031135], i.e., without degeneracy, and depends only on the control parameters of the Hamiltonian, being independent of the level degeneracy and the reservoir temperatures.
我们考虑了一个使用两个有效两能级系统的准静态量子奥托循环，这些系统在激发态下存在简并。系统通过强度为 J>0 的各向同性交换相互作用耦合，在循环过程中存在外部磁场 B 的变化。我们证明了正功条件，并表明能级简并可以作为热力学资源，因此可以提取比非简并情况更多的功，无论是否有耦合。我们还推导出了循环效率的上限。这个上限与耦合自旋-1/2 粒子系统推导出来的上限相同[G. Thomas 和 R. S. Johal, Phys. Rev. E 83, 031135 (2011)PLEEE81539-375510.1103/PhysRevE.83.031135]，即没有简并，仅取决于哈密顿量的控制参数，与能级简并和储层温度无关。
