Atom in a coherently controlled squeezed vacuum

Abstract

A broadband squeezed vacuum photon field is characterized by a complex squeezing function. We show that by controlling the wavelength dependence of its phase it is possible to change the dynamics of the atomic polarization interacting with the squeezed vacuum. Such a phase modulation effectively produces a finite range temporal interaction kernel between the two quadratures of the atomic polarization yielding the change in the decay rates as well as the appearance of additional oscillation frequencies. We show that decay rates slower than the spontaneous decay rate can be achieved even for a squeezed bath in the classical regime. For "piecewise linear" and quadratic phase modulations the power spectrum of the scattered light exhibits narrowing of the central peak due to the modified decay rates. For strong phase modulations, side lobes appear symmetrically around the central peak reflecting additional oscillation frequencies. The effect of the interaction of an atom with a squeezed light has been studied extensively. Gardiner ͓1͔ has considered the behavior of a two-level atom damped by an infinite bandwidth squeezed vacuum. He showed that the two quadratures of the atomic polarization decay at different rates. Decay rates smaller than the decay rates of spontaneous emission can be achieved for nonclassical squeezing. The presence of the two decay rates modifies the fluorescence spectrum ͓2͔. In Refs. ͓3-5͔, the interaction of a finite bandwidth squeezed vacuum with a two-level atom was investigated. Review of these and related studies is found in Ref. ͓6͔. Recently, these works were extended in Ref. ͓7͔ to include interactions with semiconductor microstructures.In the field of quantum coherent control pulse shapers ͓8͔ were used to attain prescribed phase modulation of a down converted light in order to control two photon absorption. It was shown ͓9͔ that pulses can be shaped in a way that will stretch them temporally affecting the transition probability ͓10͔. Experiments ͓11,12͔ have also been performed on two photon absorption with coherent, narrow band downconverted light, demonstrating nonclassical features which appear at very low powers ͓13-15͔ and result from time and energy correlations ͑entanglement͒ between the downconverted photon pairs.The interaction of amplitude or phase modulated classical light with a two-level system has been studied extensively both theoretically and experimentally ͑see, for example, ͓16-20͔͒. In this work, we wish to investigate the effect of controlling and modulating the relative phase of the modes of a squeezed reservoir interacting with an atom. This can be easily done by a pulse shaper arrangement as shown in Refs. ͓9,21͔. We will demonstrate that by controlling in this manner the phases of the correlations in the squeezed reservoir it is possible to control the dynamics of atomic polarization and in particular to further reduce its decay rates.We will use the standard model to describe the interaction of a two-level atom with a broadband radiation field. The atom is ass...

Bose condensation of squeezed light

“…Squeezed light can be created even from micromechanical resonators [92]. The interaction of wavelength-controlled squeezed photon field with atomic polarization has been investigated in [93]. A frequencytunable source of squeezed light was employed for spectroscopic measurements of atomic cesium [94].…”

Coherent optical control of correlation waves of spins in semiconductors

“…This is somewhat similar to a retardation of part of the random polarization signal, leading to the second rise of the spin correlation exactly after that time (T ). This analogy is however not exact since the frequency shift is a symmetric function 11 .…”

“…In the past theoretical suggestions to observe quantum optical effects in light-matter interaction involved models with squeezed radiation reservoirs interacting with atoms and semiconductors 10,11,12 . This however requires a high quality squeezed reservoir, which experimentally remains challenging to achieve.…”

“…This analogy is however not exact since the frequency shift is a symmetric function. 11 In the quadratic case ͑see Fig. 6͒, we take ͑ − 0 ͒ = T͑ − 0 ͒ 2 with a phase modulation parameter T =2 ϫ 10 4 s 2 , small average photon number N =10 −4 , optical bandwidth បB = 20 meV, and average electron kinetic en- FIG.…”

“…[10][11][12] This, however, requires a high quality squeezed reservoir, which experimentally remains challenging to achieve. Another quantum optical effect which does not involve a reservoir is related to two-photon absorption of squeezed light by a three-level system 13,14 and was demonstrated experimentally by Georgiades et al 15 Other works explored the aspect of transmission of squeezed light through bulk media [16][17][18] and photoionization.…”