The Quantum Theory of the Absorption of Light

JOHN JEFFERS EDUARD SCHMIDT

Inna Rebane

The theory of the absorption of three light pulses with an arbitrary duration in four-level systems is proposed. The pulses are in resonance with the corresponding transitions. By using the time-dependent perturbation theory the probability that the fourth level is excited at the moment t is found. The possible absorption lines and parameters on which their widths depend on are analysed.

Richard M. Sillitto

Marc-Oliver Pleinert

Anton N. Vetlugin

Coherent perfect absorption (CPA) was introduced as a classical optics phenomenon of a standing-wave absorption by a subwavelength film. In this paper, we develop a theory of CPA of quantized standing waves taking account of a subwavelength thickness of the absorber. This approach allows us to merge all known quantum effects of CPA under a single theory and introduce other regimes of CPA including CPA of NOON states with arbitrary number of entangled photons, orthogonally squeezed vacuum states, continuous variable entangled states, and Schr\"odinger cat states. Detailed analysis of the quantum regime of CPA sheds light on fundamental aspects of quantum light dissipation and its practical implementation in quantum optics and quantum information.

Xin Mi, Haitian Zhou, Ruihua Zhang +1 more

A homogeneous broadening multilevel theory of time-delay four-wave mixing with incoherent light is developed for absorption bands that consist of a series of vibrational transitions. A formula for the delay-time dependence of the signal intensity I(τ) is obtained. The differences between I(τ) derived from multilevel theory and from two-level theory are pointed out. It has been demonstrated experimentally that the multilevel theory is more suitable than the two-level theory for this type of absorption band. It is shown, in particular, that when we apply the two-level theory to the analysis of experiments in this type of absorption band, what we determine is not the dephasing time of an individual transition but the effective dephasing time, which reflects the behavior of the total absorption spectrum of the band.