Nonequilibrium quantum fluctuations of a dispersive medium: Spontaneous emission, photon statistics, entropy generation, and stochastic motion

Abstract

We study the implications of quantum fluctuations of a dispersive medium, under steady rotation, either in or out of thermal equilibrium with its environment. A rotating object exhibits a quantum instability by dissipating its mechanical motion via spontaneous emission of photons, as well as internal heat generation. Universal relations are derived for the radiated energy and angular momentum as trace formulas involving the object's scattering matrix. We also compute the quantum noise by deriving the full statistics of the radiated photons out of thermal and/or dynamic equilibrium. The (entanglement) entropy generation is quantified and the total entropy is shown to be always increasing. Furthermore, we derive a Fokker-Planck equation governing the stochastic angular motion resulting from the fluctuating backreaction frictional torque. As a result, we find a quantum limit on the uncertainty of the object's angular velocity in steady rotation. Finally, we show in some detail that a rotating object drags nearby objects, making them spin parallel to its axis of rotation. A scalar toy model is introduced to simplify the technicalities and ease the conceptual complexities and then a detailed discussion of quantum electrodynamics is presented.

Optical Instabilities and Spontaneous Light Emission by Polarizable Moving Matter

“…It should be noted that related problems have been studied in the framework of quantum theory, in connection with the problem of quantum friction [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Moreover, related optical instabilities have been recently linked to quantum friction in the case of nondispersive dielectric slabs [25][26][27] (see also Ref.…”

Interaction of a quantum field with a rotating heat bath

“…The shear flow instability that explains how the wind makes waves on the surface of the ocean is an interesting classical analog of the superradiance of bosonic fields. 4 It is instructive to consider how the thermodynamic arguments of [2,5,7] apply to this instability and to identify the hydrodynamical positive feedback, as well as the reasons why it leads to a result similar to that given by stimulated emission of bosons.…”

“…Zel'dovich's thermodynamic argument was notably refined by Bekenstein and Schiffer in [5]. More recently, the irreversibility of electromagnetically superradiant systems has been carefully investigated in [6,7]. For a thorough, modern review of rotational superradiance and its applications (with an emphasis on gravitational physics), see [8].…”

Heat meets light on the nanoscale

“…In particular, fundamental and technological solutions for thermal emission focusing can help to overcome challenges in realizing the near-field coupling schemes. Fundamental studies on the entropy and information content of correlated light fields generated by coherent thermal sources are also important [277][278][279], especially in the processes of light absorption and emission away from thermal equilibrium, when light-matter interactions occur over time scales too short for the thermalization process to take place. This is illustrated by a recent striking demonstration of efficient optical refrigeration via the heat transport between a thermal bath and a non-equilibrium exciton-polariton fluid [280].…”