Ballistic dynamics of flexural thermal movements in a nanomembrane revealed with subatomic resolution

Abstract

Flexural oscillations of freestanding films, nanomembranes, and nanowires are attracting growing attention for their importance to the fundamental physical and optical properties and device applications of two-dimensional and nanostructured (meta)materials. Here, we report on the observation of short–time scale ballistic motion in the flexural mode of a nanomembrane cantilever, driven by thermal fluctuation of flexural phonons, including measurements of ballistic velocities and displacements performed with subatomic resolution, using a free electron edge-scattering technique. Within intervals <10 μs, the membrane moves ballistically at a constant velocity, typically ~300 μm/s, while Brownian-like dynamics emerge for longer observation periods. Access to the ballistic regime provides verification of the equipartition theorem and Maxwell-Boltzmann statistics for flexural modes and can be used in fast thermometry and mass sensing during atomic absorption/desorption processes on the membrane.

Picophotonic localization metrology beyond thermal fluctuations

“…With ultrafast image sensors (>10 Mfps, as are now becoming accessible), our method may be applied to the study of dynamics and transient processes at the (sub)nanoscale. For example: the study of Brownian motion thermodynamics of nano-objects, including the ballistic regime 17 and non-Markovian processes of thermal fluctuation, which may have applications in fast thermometry and mass measurement; the study of electron and plasmon quantum transport through atomic scale gaps [18][19][20] ; configuration chemistry of individual molecules; protein folding 21 ; and other time-dependent events in macromolecules, nanomachines and 2D materials, where flexural, phononic modes are now understood to be of critical importance to thermal, electrical and mechanical properties [22][23][24] .…”

Photonic metamaterial analogue of a continuous time crystal

“…It paves the way towards comprehensive studies of dynamic many-body states in the strongly correlated regime in a classical system that complements the cold atom and spin platforms where many-body quantum states of bosonic or fermionic matter can be investigated. These studies can be facilitated by direct access to the nanowire positions using recently developed atomic scale techniques for detecting localization and movement of nanoscale strings and cantilevers 32,33 . The dynamics of transitions from the stochastic and ballistic thermal motion of individual nanowires into the collective superradiant state at difference time scales and at various ambient temperatures are also of interest for nanoscale thermodynamics 32 .…”

“…These studies can be facilitated by direct access to the nanowire positions using recently developed atomic scale techniques for detecting localization and movement of nanoscale strings and cantilevers 32,33 . The dynamics of transitions from the stochastic and ballistic thermal motion of individual nanowires into the collective superradiant state at difference time scales and at various ambient temperatures are also of interest for nanoscale thermodynamics 32 .…”

Roadmap for Optical Metasurfaces

“…Metamaterial-enabled noninvasive single-shot optical metrology with sub-Brownian resolution, that can be performed with high frame rate image sensors, opens up the exciting field of picophotonics. This includes the study of Brownian motion thermodynamics of nano-objects, including the ballistic regime; the study of Van Der Waals forces and non-Hamiltonian forces in nanomechanics; , configuration chemistry of individual molecules; protein folding; and other dynamic events in macromolecules and nanomachines, such as time crystals …”