Eur. Phys. J. Special Topics 227, 203–216 (2018)
https://doi.org/10.1140/epjst/e2018-00125-6

Regular Article

Speeding up thermalisation via open quantum system variational optimisation

¹ Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076, India
² Department of Physics, Carnegie-Mellon University, Pittsburgh, PA 15213, USA
³ School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
⁴ Complexity Institute, Nanyang Technological University, Singapore 639673, Singapore
⁵ Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
⁶ Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543, Singapore

^a e-mail: sai@quantumlah.org

Received: 28 November 2017
Received in final form: 26 February 2018
Published online: 28 September 2018

Abstract

Optimising open quantum system evolution is an important step on the way to achieving quantum computing and quantum thermodynamic tasks. In this article, we approach optimisation via variational principles and derive an open quantum system variational algorithm explicitly for Lindblad evolution in Liouville space. As an example of such control over open system evolution, we control the thermalisation of a qubit attached to a thermal Lindbladian bath with a damping rate γ. Since thermalisation is an asymptotic process and the variational algorithm we consider is for fixed time, we present a way to discuss the potential speedup of thermalisation that can be expected from such variational algorithms.