University of Manchester / Physics and Astronomy

Owing to sustained efforts during the past decades, “quantum technologies” have evolved from theory to the first wave of commercial devices. However, many prospective applications demand an accuracy in the manipulation of ultra-cold microscopic systems that is currently out of reach. Further progress will require design principles that are both thermodynamically efficient and robust to environmental disturbances. Resolving these issues is paramount within the emerging field of quantum thermodynamics.

Here my research will address a fundamental question: when driving a quantum system from one state to another, what is the most thermodynamically optimal route to take? Quantifying what is ‘optimal’ in quantum thermodynamics is a subtle issue, as there are a multitude of interrelated factors that must be taken into account. While energy efficiency is one figure of merit, increasing this typically comes at a price of reduced power output. Furthermore, a microscopic system can also suffer from unwanted statistical fluctuations that render it unreliable when performing tasks such as cooling, converting heat into work or processing information. This means that the most efficient route in a given amount of time may not be the most reliable or powerful, and one must account for this trade-off when designing any quantum thermal machine or device. The aim of this research will be to develop novel methods for optimising this balance between the power, efficiency and reliability of achievable thermodynamic protocols in the quantum regime.

To achieve this I will utilise new techniques from information geometry, which will provide a means of describing thermodynamic processes in terms of an underlying geometric representation. With this approach, optimal processes can be determined by finding the shortest curves (‘geodesics’) within the space of control parameters. This method will be used to tackle a broad range of optimisation problems such as energy-efficient quantum cooling, minimising heat dissipation in quantum computing and improving the work output of quantum heat engines. Bridging quantum thermodynamics with information geometry will lend new insight into the interplay between power, efficiency and reliability in the microscopic regime, while providing a powerful framework for optimising the performance of experimentally realisable quantum thermal devices.