Non-classical properties of quantum amplifiers

Yun Zhang, Katsuyuki Kasai, Masayoshi Watanabe

Qiang Ke, Yifan Wang, Yanbei Cheng +1 more

Based on the squeezed vacuum (SV) and the quadratic function of the photon number operator, we introduce the quadratically amplified squeezed vacuum (QASV) in this paper. We study the intensity, noise, squeezing effect, antibunching effect, and Wigner function of the QASVs. Compared with the SV, the QASVs have distinctive signal characters and possess peculiar non-classical properties in the proper range of interaction parameters.

Crispin W. Gardiner, Matthew J. Collett

Vitaliy V. Shtykov, Sergey M. Smolskiy

R. Loudon, Terence J. Shepherd

The properties of a linear optical amplifier or attenuator in which the input light is coupled to a collection of non-saturable atoms are considered. The photon-number factorial moments and probability distribution of the amplifier output are derived for arbitrary input statistics. Relations are obtained between the output and input variances in photon number, phase-angle cosine, and electric-field magnitude. The effects of amplification and attenuation on signal-to-noise ratio are obtained for both direct and homodyne detection. Particular attention is paid to the extents to which the non-classical properties of photon antibunching and squeezing are preserved by amplification and attenuation. It is found that both properties can at best survive only twofold intensity amplification.

M. S. Kim

We investigate the influence of phase-sensitive reservoirs (attenuators) and phase-sensitive amplifiers on quantum-mechanical superposition (Schrodinger cat) states of light. In particular, we study how the quantum coherence emerging as a consequence of quantum interference between two coherent state is decaying under the influence of the environment.