Theory of Coherence and Photon Statistics of Classical and Nonclassical Light on a Microscopic Basis

Hai-Yan Yao, Sheng-Wen Li

Abstract We study the photoelectric current generated by a driving light with nonclassical photon statistics. Due to the nonclassical input photon statistics, it is no longer enough to treat the driving light as a planar wave as in classical physics. We make a quantum approach to study such problems, and find that: when the driving light starts from a coherent state as the initial state, our quantum treatment well returns the quasi-classical driving description; when the the driving light is a generic state with a certain P function, the full system dynamics can be reduced as the P function average of many ‘branches’—in each dynamics branch, the driving light starts from a coherent state, thus again the system dynamics can be obtained in the above quasi-classical way. Based on this quantum approach, it turns out the different photon statistics does make differences to the photoelectric current. Among all the classical light states with the same light intensity, we prove that the input light with Poisson statistics generates the largest photoelectric current, while a nonclassical sub-Poisson light could exceed this classical upper bound.

Ramabhadra Vasudevan

John Rarity, P. R. Tapster

D. N. Sob’yanin

A theory of Bose-Einstein condensation (BEC) of light in a dye microcavity is developed. The photon polarization degeneracy and the interaction between dye molecules and photons in all of the cavity modes are taken into account. The theory goes beyond the grand canonical approximation and allows one to determine the statistical properties of the photon gas for all numbers of dye molecules and photons at all temperatures, thus describing the microscopic, mesoscopic, and macroscopic light BEC from a general perspective. A universal relation between the degrees of second-order coherence for the photon condensate and the polarized photon condensate is obtained. The photon Bose-Einstein condensate can be used as a new source of nonclassical light.

Malvin Carl Teich, Bahaa E. A. Saleh

Antibunching, photon-number squeezing, and quadrature squeezing represent characteristics of nonclassical electromagnetic fields that have been observed in the laboratory. Experiments involving nonclassical light often make use of beam splitters to superimpose light beams. We discuss the photon statistics that arise from the superimposition of two arbitrary (not necessarily independent) quantum fields at a device such as a beam splitter. The photomixing density operator of the superimposition field is presented, and the behavior of the balanced mixer is examined in the general case.1 The failure of classical probability theory as a descriptor of the relationship between the photon statistics at the output and at the input of the beam splitter is elucidated.

Imrana Ashraf Zahid, Vasudevan Lakshminarayanan