Speaker
Description
Nanoscale devices that convert energy into useful work are becoming increasingly common. A critical challenge is controlling energy transduction at the nanoscale. In this context, quantum measurement and the associated acquisition of information can be leveraged to guide and enhance work output through feedback control. We explore a quantum information engine (QIE) as a prototype energy-transducing nano device controlled by measurement. This engine utilizes the information exchange between a working medium, modeled as a two-level system, and a meter, modeled as a quantum harmonic oscillator. However, this information transfer is not instantaneous; it depends on the measurement time, which is the time required to establish a correlation between the quantum system and the meter. This measurement time sets a lower bound on the cycle time of the QIE, making information acquisition a crucial resource for the process.
We examine the energetic cost of quantum measurement and the associated information acquisition during finite-time operations. Heat and work flows are analyzed as functions of the system and meter temperatures to demonstrate that the QIE can operate in different modes: as a heat engine, a heat valve, a refrigerator, and a 'true' information engine, which extracts work and cools a colder bath. We show that the QIE's performance in terms of power output is limited for very short measurement times, in the Zeno limit. To increase power output, it is necessary to extend the measurement time; however, this results in a higher cost of measurement. We carefully analyze the relationship between work output and cost in different operating regimes of the QIE to determine optimal conditions for maximizing net total work output and achieving high engine performance.
