Thermodynamics of misaligned expectations

• Main Author: Gupta, Chaitanya
• Other Authors: Gu Mile
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Science::Physics
• Online Access: https://hdl.handle.net/10356/157012
• Institution: Nanyang Technological University

Protocols can be used to evolve a quantum system from one state to another by dictating the Hamiltonian of the system and its interactions with the environment. For instance, work-extraction protocols exploit the link between physical and information entropy to extract work from a quantum system. However, the efficiency of such protocols depend on the initial state injected. Entropy production can be used to quantify the efficiency of such protocols. Recent work has shown how the minimally dissipative state, i.e., initial state that result into minimum entropy production can be found for a protocol on a qubit. It has also been established that the extra dissipation that results from the injection of another state that is not minimally dissipative into the protocol can be quantified by the quantum relative entropy of the state with respect to the minimally dissipative state. We verify this theoretical framework for work-extraction protocols on a qubit. We extend this theoretical framework to multi-level quantum systems, and thereby present a method to find the minimally dissipative state for the case of multi-level quantum systems. We verify our results on a driven qutrit system described by the V configuration. Then, mirroring the classical Szilard engine, we study a work-extraction protocol on a multi-level quantum system described by a double-well potential and coupled to a Bosonic bath. We find the minimally dissipative state for the protocol and verify the equivalence of extra dissipation and quantum relative entropy.