Entropy Production in an Elementary, Light Driven Micro-Machine

Abstract

We consider the basic, thermodynamic properties of an elementary micro-machine operating at colloidal length scales. In particular, we track and analyze the driven stochastic motion of a carefully designed micro-propeller rotating unevenly in an optical tweezers, in water. In this intermediate regime, the second law of macroscopic thermodynamics is satisfied only as an ensemble average, and individual trajectories can be temporarily associated with decreases in entropy. We show that our light driven micro-propeller satisfies an appropriate fluctuation theorem that constrains the probability with which these apparent violations of the second law occur. Implications for the development of more complex micro-machines are discussed.

A topological fluctuation theorem

“…Remarkably, the theorem predicts that this ratio is topologically protected for closed cycles in phase space, as discussed recently for the one-dimensional case in ref. 58 , thus providing some insight for the optimization and design of micro-machines.…”

Stochastic Hopf bifurcations in vacuum optical tweezers

“…Such systems are representative of a broader physical class including, for instance, firing of neurons [25,26], laser dynamics [27,28], and electrochemical reactions [38]. Although we have covered the salient properties of this system, there remains much to understand concerning the detailed stochastic dynamics, entropy production [39][40][41], and so on. Second, the unevenness of the limit cycles lends itself to various kinds of synchronization [42,43] (which, in this case, may be mediated by optical interactions, e.g., Ref.…”