Time-asymmetric fluctuations of light and the breakdown of detailed balance.

Temporal fluctuations of the light radiated by a photoemissive source are studied through the cross correlation of output fields. Whereas microscopic reversibility guarantees time-symmetric fluctuations in thermal equilibrium--where detailed balance holds--away from equilibrium time asymmetry is permitted. Examples of time asymmetry in cavity QED are reported.

Quantum state reduction and conditional time evolution of wave-particle correlations in cavity QED.

We report measurements in cavity QED of a wave-particle correlation function which records the conditional time evolution of the field of a fraction of a photon. Detection of a photon prepares a state of well-defined phase that evolves back to equilibrium via a damped vacuum Rabi oscillation. We record the regression of the field amplitude.

Giant violations of classical inequalities through conditional homodyne detection of the quadrature amplitudes of light.

Conditional homodyne detection is proposed as an extension of the intensity correlation technique introduced by Hanbury-Brown and Twiss [Nature (London) 177, 27 (1956)]. It detects giant quadrature amplitude fluctuations for weakly squeezed light, violating a classical bound by orders of magnitude. Fluctuations of both quadrature amplitudes are anomalously large.