I shall build a platform in the solid state to realize engines that can enable the study of thermodynamics in open quantum systems. In particular, I want to answer the question: what is the efficiency of an electromechanical engine in which fluctuations are important and quantum effects might arise? Little is known about the thermodynamics of quantum devices evolving, fluctuating and coupling to each other and to the environment. Open questions range from the definition of work in the quantum regime to the efficiency of quantum thermodynamic cycles. Classical thermodynamics has been established since the 19th century; quantum thermodynamics is now blossoming in the theoretical domain, but is still in its infancy experimentally, due to the lack of control over thermodynamic processes in this regime. Harnessing electromechanical circuits in the solid-state, I will build a platform to study the efficiency and power of quantum engines. This platform could inform the study of biomotors and the design of efficient on-chip nanomachines. By harnessing statistical fluctuations, the requirements to preserve coherence might become less demanding. It could also help reveal the interplay between spin, charge and heat currents. An experimentally grounded understanding of quantum thermodynamics will advance energy harvesting, dissipation and thermalisation in quantum devices. It could enable future quantum devices to be refined through fully informed design. It could also uncover unique behaviours that open the way for new technologies such as new on-chip refrigeration and sensing techniques or innovative means of storing energy. It will pave the way for experimental tests to concepts such as work in the quantum regime, quantum fluctuations and autonomous machines. My research will have applications in both classical and quantum computing.
Thermodynamics at the nanoscale was first explored in molecules and soft matter at room temperature. To significantly advance the field it is now necessary to seek platforms that allow for control of heat and work exchanges in a thermodynamic process and can be extended to the quantum regime.
Solid-state circuits have demonstrated their potential in the quantum arena, and are among the leading candidates for the realisation of quantum technologies. These circuits have the advantage that they can couple electronic properties to other on-chip degrees of freedom, such as mechanical motion, enabling hybrid architectures. In the same way that Joule’s experiment demonstrated that motion and heat were mutually interchangeable, QuThenS aims to link motion with heat and work in the nanoscale.
Previous thermodynamic experiments in the solid state have used single electron transistors and quantum dots in the classical regime, and superconducting qubits and diamond defects in the quantum regime. My platform will permit direct determination of stored and retrieved mechanical work, by introducing a mechanical resonator and enabling measurements of its displacement.
I will lead a group that harnesses the capabilities of solid-state hybrid devices to provide a platform to answer the most pressing questions in the thermodynamics of open quantum systems. Solid-state circuits have been explored extensively for the realisation of qubit devices, with governments and companies worldwide, including Google, Microsoft, Intel and IBM, investing substantially to unleash their potential for quantum computing. My group will be the first to use semiconductor qubit technology for quantum thermodynamic experiments.
The main goals of the project are:
o To establish a quantum thermodynamics platform in the solid state. Milestone: I will build a platform for experimental verifications of descriptions of heat transport, entropy production and work in the context of quantum mechanics.
o To achieve work exchange between a mechanical battery and a two-level system coupled to a heat bath. Milestone: I will demonstrate that mechanical work can be stored and retrieved in a solid-state platform, opening the path for nanoscale quantum engines.
o To realize the first electromechanical engine in a solid-state circuit that can access the quantum regime. Milestone: I will measure the efficiency of the engine, introduce spin states, and characterise the effect of the mechanics. In this way, I will lead the way towards the realization of electromechanical quantum engines, which will inspire other nanoscale machines, impacting fields from biology to robotics.
