Electrons, Spins, and Mechanics for Quantum Engines

Out-of-equilibrium phenomena in nanoscale devices can be harnessed to realise on-chip engines and refrigerators. I will show that fully suspended carbon nanotube devices have exceptional capabilities to explore thermodynamics at the nanoscale, combining electron tunnelling, spin physics, and high-frequency motion.

In these devices, and in the absence of a mechanical drive, the interplay between single electron tunnelling and mechanical motion can give rise to self-sustained oscillations. Fluctuations can make these self-oscillations irrupt, vanish, and exhibit a bistable behaviour causing hysteresis cycles. We find that self-oscillations can be stable for over 20 seconds, many orders of magnitude above electronic and mechanical characteristic timescales. I will also show that the mechanical motion of the carbon nanotube couples to single electron spins. This coupling, mediated by spin-orbit interaction, would allow for the study of fluctuations in electromechanical devices exhibiting quantum effects.