Hyperspectral Electromechanical Imaging at the Nanoscale: Dynamical Backaction, Dissipation, and Quantum Fluctuations

We report a new hyperspectral electromechanical imaging platform enabling local heating of nanostructures and simultaneous measurement of their mechanical fluctuations, with nanometric resolution. We use this platform to image the thermally activated nanomechanical dynamics of a 40 nm diameter nanowire whose mechanical losses are dominated by a single localized defect while scanning a heat source across its surface. We develop a thermal backaction model, which we use to demonstrate a close connection among the structure of the nanowire, its thermal response, its dissipation, and its fluctuations. We notably show that the defect behaves as a single fluctuation hub, whose e-beam excitation yields a far off-equilibrium vibrational state largely dominated by the quantum fluctuations of the heating source. Our platform is of interest for future quantitative investigation of fundamental nanoscale dynamical phenomena and appears to be a new playground for exploring quantum thermodynamics in the strongly dissipative regime and at room temperature.