Abstract: Thermodynamic laws have been key for the design of useful everyday devices from car engines and fridges to power plants and solar cells. Technology’s continuing miniaturisation to the nanoscale is expected to soon enter regimes where standard thermodynamic laws do not apply. I will briefly introduce quantum thermodynamics, an emerging research field that aims to uncover the thermodynamic laws that govern small ensembles of systems that follow non-equilibrium dynamics and can host quantum properties [1]. I will then discuss a nanoscale thermodynamic experiment with heated optically trapped nanospheres in a dilute gas [2]. By developing a new theoretical model that captures the non-equilibrium situation of the particles, we were able to measure the surface temperature of the trapped spheres and observe temperature gradients on the nanoscale. In the second part of the talk I will discuss recent theoretical advances in defining thermodynamic work in the quantum regime. By introducing a process that removes quantum coherences we were able to show that work cannot only be extracted from classical non-equilibrium systems, additional work can be extracted from quantum coherences [3].

[1] Quantum thermodynamics, S. Vinjanampathy, J. Anders, Contemporary Physics 57, 545 (2016).
[2] Nanoscale temperature measurements using non-equilibrium Brownian dynamics of a levitated nanosphere, J. Millen, T. Deesuwan, P. Barker, J. Anders, Nature Nanotechnology 9, 425 (2014). 
[3] Coherence and measurement in quantum thermodynamics, P. Kammerlander, J. Anders, Scientific Reports 6, 22174 (2016).