The role of atom-field correlations in coherent interactions

Gaétan Hercé, Jan‐Philipp Bureik, Antoine Ténart +3 more

We study the full counting statistics (FCS) of quantum gases in samples of thousands of interacting bosons, detected atom by atom after a long free-fall expansion.In this far-field configuration, the FCS reveals the many-body coherence from which we characterize iconic states of interacting lattice bosons by deducing their normalized correlations g (n) (0) up to the order n = 6.In Mott insulators, we find a thermal FCS characterized by perfectly contrasted correlations g (n) (0) = n!.In interacting Bose superfluids, we observe small deviations to the Poisson FCS and to the ideal values g (n) (0) = 1 expected for a pure condensate.These deviations become larger as we increase the interaction strength and reveal the role of the quantum depletion of the condensate on many-body coherence.The approach to many-body correlations demonstrated here is readily extendable to characterize a large variety of interacting quantum states and phase transitions.

P. R. Berman, Huy Minh Nguyen, Yefeng Mei +2 more

When a coherent field is combined with the phase-matched output of an atomic ensemble, the second-order correlation function of the total field can exhibit superbunching or antibunching. Homodyning the reference field with the atomic emission can amplify the nonclassical characteristics of the atomic emission. A theoretical description of these phenomena is presented. It is pointed out that, even if the number of excitations in the ensemble is much less than unity, truncating a factorized state to have at most two excitations can lead to errors in calculating the second-order correlation function. We also include the effects of dephasing produced by Rydberg-Rydberg interactions and show how they modify the bunching and antibunching that occur in the absence of atom-atom interactions. It is shown that the particle separation probability distribution and the joint particle separation probability distribution play critical roles in determining the effects of dephasing.

马蓉 Ma Rong, 艾合买提·阿不力孜 Ahmad Abliz, 艾尔肯江·艾木都拉 Erkinjan Hamdulla +1 more

Carlos L. Garrido Alzar, Luciano Soares da Cruz, J. G. Aguirre Gómez +7 more

We present a series of experiments measuring intensity fluctuations and correlations of laser beams after propagation through an atomic vapour at room temperature in situations where coherent effects play a major role. In particular, we investigate these properties in the condition of electromagnetically induced transparency (EIT) in three-level lambda systems and in degenerate two-level systems. In a similar way, we also study the Hanle-EIT effect and electromagnetically induced absorption (EIA) in degenerate two-level systems. These results show the great influence of coherent interaction with the atomic system over the noise properties of the macroscopic laser fields, and indicate new sensitive ways of probing an atomic sample.

A. V. Andreev, J. George Adashko