Faculty @ Institute for Basic Science

Monday June 27 – 12.00 BST

Effects of measurements on quantum devices

In this talk, I’ll introduce a method, known as repeated contacts, that allows us to infer the sum of the values of an observable taken during contacts with a pointer state [1]. I’ll first show the superiority of this approach with the results of the same number of generalized Gaussian measurements of the considered observable. The proposed repeated contact approach could be beneficial to measure the work output of a quantum Otto heat engine and I’ll demonstrate this using a two-level system as the working substance [2]. I’ll discuss the imperfect thermalizing engine under Landau-Zener work strokes and show that the repeated contact scheme is minimally invasive and gives enhanced performance metrics (efficiency, power output, and reliability) as compared to the standard repeated generalized Gaussian measurements. Lastly, I’ll consider the charging of a quantum battery using an Otto engine and demonstrate that periodic measurement on the battery speeds up its charging of internal energy, but sacrifices the ergotropy [3]. Overall, I’ll show the importance of considering the effects of quantum measurements using different measurement protocols on the performance of a machine. 

[1] J. Thingna and P. Talkner, Phys. Rev. A 102, 012213 (2020). 
[2] J. Son, P. Talkner, and J. Thingna Phys. Rev. X Quantum 2, 040328 (2021). 
[3] J. Son, P. Talkner, and J. Thingna (in preparation). 

Categories: Talks Monday June 27