Simplifying multi-level thermal machines using virtual qubits
This event is part of the Biophysics/Condensed Matter Seminar Series.
Investigating the control of thermal machines in the quantum regime allows one to explore the fundamental limits of thermodynamic tasks. To study such processes, it is usual to consider a few quantum-mechanical degrees of freedom interacting with a large environment, which one does not have detailed control over. Higher-dimensional machines are harder to simulate exactly, and hence much of the focus is on models that are simple enough to be treatable by master equations, such as a few qubits. Expanding the target system to multi-level systems beyond qubits is a challenge. In this work , we address this problem for three-level systems, as well as arbitrary-level systems, coherently interacting with several virtual qubits in the context of reset master equations. We investigate the steady-state solution for three-level systems coupled to virtual qubits and identify properties of multi-level thermal machines. In this talk, I will start with the introduction of the history of thermodynamic tasks in the quantum regime and virtual qubits before presenting the findings of this work. I will then propose a method to enhance the performance of the paradigmatic three-level maser/laser to show the advantages of the results obtained from this work.
 A. Usui, W. Niedenzu, and M. Huber, Simplifying multi-level thermal machines using virtual qubits, arXiv:2009.03832.