Abstract
Energy storage is a basic physical process with many applications. When considering this task at the quantum scale, it becomes important to optimise the non-equilibrium dynamics of energy transfer to the storage device or battery. Here, we tackle this problem using the methods of quantum feedback control. Specifically, we study the deposition of energy into a quantum battery via an auxiliary charger. The latter is a driven-dissipative two-level system subjected to a homodyne measurement whose output signal is fed back linearly into the driving field amplitude. We explore two different control strategies, aiming to stabilise either populations or quantum coherences in the state of the charger. In both cases, linear feedback is shown to counteract the randomising influence of environmental noise and allow for stable and effective battery charging. We analyse the effect of realistic control imprecisions, demonstrating that this good performance survives inefficient measurements and small feedback delays. Our results highlight the potential of continuous feedback for the control of energetic quantities in the quantum regime.
Highlights
The ability to control the quantum dynamics of mesoscopic systems has opened a broad research frontier in the physical sciences, spanning metrology [1], information processing [2], and non-equilibrium statistical mechanics [3]
It has been shown that collective operations can enhance the charging power of composite quantum batteries [17, 18]. These predictions have inspired a substantial body of theoretical research aiming to harness quantum or many-body effects in order to improve the performance of energy storage devices
We have explored the use of linear feedback control to power a qubit charger coupled to a quantised, finite-dimensional battery
Summary
The ability to control the quantum dynamics of mesoscopic systems has opened a broad research frontier in the physical sciences, spanning metrology [1], information processing [2], and non-equilibrium statistical mechanics [3]. A fruitful way to gain insight is through specific examples of thermodynamic processes in the quantum regime, such as energy storage and extraction. It has been shown that collective operations can enhance the charging power of composite quantum batteries [17, 18]. These predictions have inspired a substantial body of theoretical research aiming to harness quantum or many-body effects in order to improve the performance of energy storage devices. Numerous quantum battery architectures have since been proposed [19,20,21,22,23,24,25,26,27] and the effects of different physical phenomena — ranging from entanglement [28, 29] to many-body localisation [30] — have been extensively investigated
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