Alladi Ramakrishnan Hall

Work extraction from thermal noise by measurements and nonlinear interactions in quantum optical setups

Avijit Misra

Weizmann Institute, Israel

In this talk, I will try to elucidate the rapport of work and information in the context of a minimal quantum mechanical setup. Specifically, I will talk about a converter of heat to work wherein the input consists of a single oscillator mode prepared in a hot thermal state along with few much colder oscillator modes. I will compare the efficiencies of work extraction and the limitations of power in reversible manipulations and different, generic, measurement strategies in our minimal setup. I will demonstrate that extraction of work by observation and feed-forward (WOF) that only measures a small fraction of the input, is clearly advantageous to the conceivable alternatives, by generalizing a method based on optimized homodyning. However, the main drawback of work extraction by measurement is it inevitably requires feed-forward and outcome dependent control steps. To circumvent this, I will briefly discuss autonomous, coherent work extraction exploiting non-linear cross-Kerr interaction. Our results may become a basis of a practical strategy of converting thermal noise to useful work in optical setups, such as coherent amplifiers of thermal light, as well as in their optomechanical and photovoltaic counterparts.

References: Phys. Rev. Lett. 127 (4), 040602 (2021); Phys. Rev. E 106 (5), 054131 (2022); Sci. Advs. In press ( arXiv:2108.10157)