Statistical properties of the laser emission in a low-Q cavity

Jia‐pei Zhu, Hui Huang, Gao‐xiang Li

We theoretically investigate the influence of the phonon-mediated coupling on the properties of the laser generated by a single red-detuned quantum dot (QD), where the QD is coherently driven and coupled to a microscopic cavity which can be engineered in a photonic band-gap (PBG) material. In the low-temperature limit, the phonon-mediated coupling is deleterious to the emission of photon into cavity field and the threshold behavior of the laser persists after the inclusion of the phonon-mediated processes. Without being engineered in the PBG material, if the damping rate $\ensuremath{\kappa}$ of the cavity is close to but smaller than the phonon-mediated spontaneous emission rate $\ensuremath{\gamma}$ of the dot, the photon statistics of the cavity field change from super-Poissonian to sub-Poissonian. The nonclassical effect can be achieved due to the phonon-mediated processes induced by the electron-phonon interaction and the off-resonant dot-cavity coupling. The nonclassical effect can be enhanced by the PBG material. When the effect of the thermal phonon is taken into account, the cavity field exhibits the super-Poissonian property. If $\ensuremath{\kappa}$ is much smaller than $\ensuremath{\gamma}$, the phonon-mediated processes can lead to the increase (decrease) of the photons provided that the incoherent pumping rate is lower (higher) than the effective phonon-mediated threshold. But, if $\ensuremath{\kappa}$ is close to or larger than $\ensuremath{\gamma}$, the emission of the photon may dominate the absorption process, strengthening the intensity of the cavity field.

Perry R. Rice, H. J. Carmichael

Hannes Risken

V. R. Thakar, Arun Bahuleyan, V. I. Gokul +2 more

We study self-sustained cavity emission from driven atoms in collective strong coupling. The cavity emission occurs over a wide range of atom-cavity and drive-laser detunings without any external input to the cavity mode. Second-order correlation measurements ${g}^{(2)}(\ensuremath{\tau})$ further reveal unanticipated phenomena in the observed cavity emission such as (1) damped oscillations at two frequencies and (2) significantly distinct ${g}^{(2)}(\ensuremath{\tau})$ for different polarization components. The intricate relation between cavity-emission intensity, drive-laser detuning, and atom-cavity detunings is explained. A possible mechanism for the damped oscillations with two frequency components in ${g}^{(2)}(\ensuremath{\tau})$ is suggested. Measurements show the existence of two separate polarization-decoupled mechanisms with distinct photon statistics, through which energy is transferred from the drive field to the cavity field. The statistical properties and mechanisms underlying cavity emission present valuable insights for extending nondestructive detection techniques to the regime of collective strong coupling.

Chimdessa Gashu Feyisa

The quantum and statistical properties of light generated by an external classical field in a correlated emission laser with a parametric amplifier and coupled to a squeezed vacuum reservoir are investigated using the combination of the master and stochastic differential equations. First, the solutions of the cavity-mode variables and correlation properties of noise forces associated to the normal ordering are obtained. Next, applying the resulting solutions, the mean photon number of the separate cavity modes and their crosscorrelation, smallest eigenvalue of the symplectic matrix, mean photon number, intensity difference fluctuation, photon number variance, and intensity correlation are derived for the cavity-mode radiation. The entanglement produced is studied employing the logarithmic negativity criterion. It is found that pumping atoms from the lower energy state to excited state, introducing the nonlinear crystal into the cavity and coupling the system to a biased noise fluctuation, generate a bright and strong squeezing and entanglement with enhanced statistical properties although the atoms are initially in the ground state.

H. Risken