Physical interpretation for the correlation spectra of electromagnetically-induced-transparency resonances

Abstract

The phenomenon called Electromagnetically Induced Transparency (EIT) may induce different types of correlation between two optical fields interacting with an ensemble of atoms. It is presently well known, for example, that in the vicinity of an EIT resonance the dominant correlations at low powers turn into anti-correlations as power increases. Such correlation spectra present striking power-broadening-independent features, with the best condition for measuring the characteristic linewidth occurring at the highest powers. In the present work we investigate the physical mechanisms responsible for this set of observations. Our approach is first to reproduce these effects in a better controlled experimental setup: a cold atomic ensemble, obtained from a magneto-optical trap. The results from this conceptually simpler system were then compared to a correspondingly simpler theory, which clearly relates the observed features to the interplay between two key aspects of EIT: the transparency itself and the steep normal dispersion near two-photon resonance.

Electromagnetically-induced-transparency intensity-correlation power broadening in a buffer gas

“…The experimental result that the central EIT intensity correlation peak broadens with optical power is a challenge to the simple theories describing EIT-noise correlation, as their numerical evaluation does not include a priori predictions of this behavior. In fact, the central noise correlation peak has been shown in experiment and theory to be impervious to broadening at low powers even as the underlying EIT peaks themselves suffer from power-broadening [15,17]. A relationship between the laser's RIN and power broadening of the correlation peak has been established experimentally and modeled theoretically in [14].…”

“…Simple theory models of EIT noise generally start with analysis of a single-site three-level system, either treating the time evolution of the coherences that contribute to the EIT noise directly or as an ensemble average over static responses of such a system, see [15,17,25,28]. In this manuscript we use the latter approach.…”

Electromagnetically induced transparency (EIT) amplitude noise spectroscopy

“…In this case we treat the light as classical single mode field and then calculate/measure the relevant properties of the light after exiting the medium. [8][9][10][11][12][13]. Less coherent sources, such as the generic free running semiconductor laser diode used in this experiment, have broad frequency spectra (≈ 80 MHz) and the resulting EIT atom-light interaction is not well modelled in terms of polarization states of a single optical mode.…”

“…EIT intensity noise correlation spectra can be well modelled with a theory based on a reduced number of optical modes and are interesting spectroscopic probes [8][9][10][11][12][13]. They are understood as examples of the more general process of phase noise to amplitude noise conversion in atomic systems [14,15].…”

Espectroscopia de correlação em condição de transparência eletromagneticamente induzida: regime dinâmico e ressonâncias das bandas laterais em átomos frios

“…Após a montagem do sistema de captura de imagem para medir a temperatura da nuvem e das primeiras espectroscopias de estados vestidos da nuvem, em 2010 tive a oportunidade de começar a montagem para obter EIT na nuvem deátomos frios. Em 2013 fomos os primeiros a fazer uma ampla análise espectroscópica da correlação em condição de EIT emátomos frios [43,44], em colaboração com o grupo de física deátomos frios da Universidade Federal de Pernambuco (UFPE). Nesta interface empregamos um laser de diodo para gerar dois feixes que interagem em condição de EIT com uma nuvem deátomos frios numa MOT (ver figura 5).…”