Effect of decoherence on the radiative and squeezing properties in a coherently driven trapped two-level atom

Abstract

Analysis of the effects of decoherence on the radiative and squeezing properties of a coherently driven two-level atom trapped in a resonant cavity applying the corresponding master equation is presented. The atomic dynamics as well as the squeezing and statistical properties of the emitted radiation are investigated. It is found that the atom stays in the lower energy level more often at steady state irrespective of the strength of the coherent radiation and thermal fluctuations entering the cavity. Moreover, a strong external coherent radiation results the splitting of the line of the emission spectrum, whereas the decoherence broadens the width and significantly decreases the height. It is also found that the emitted radiation exhibits photon anti-bunching, super-Poissonian photon statistics and squeezing, despite the presence of the decoherence which is expected to destroy the quantum features.

Atomic dynamics and radiative properties of a two-level atom in a resonant cavity coupled to a finite bandwidth squeezed input

“…As critical observation of Figure 4 indicates, the height of the spectrum at ! ¼ 0 decreases with the strength of the finite bandwidth biased input, contrary to what has been obtained when the cavity is coupled to broadband thermal and squeezed vacuum reservoirs [1,2]. Therefore, in view of the earlier communications, it is possible to relate the shrinking of the height of the emission spectrum at !…”

“…It must be common knowledge by now that, in the absence of the external coherent radiation and noise fluctuations entering the cavity, the atom occupies the lower atomic energy level at steady state irrespective of its initial state. In one of the earlier reports [2], it is strongly argued that there is no essential difference in the population inversion when the atom is coupled to the biased and unbiased broadband noise fluctuations. However, as clearly shown in Figure 1, when finite bandwidth biased noise fluctuations are able to enter the cavity, the population inversion acquires a characteristic dip for certain values of the intensity of the external driving radiation.…”

“…Successively emitted radiation turns out to exhibit squeezing even when the cavity is coupled to unbiased noise fluctuations for narrow pockets of the amplitude of the external radiation [2]. In addition, recent analysis based on the two-time second-order correlation function shows that the emitted photon can exhibit super Poissonian photon statistics for larger delayed time [1,2]. Most of the studies dealing with a two-level atom coupled to a squeezed vacuum reservoir assume that the width of the reservoir modes is much larger than the atomic line width and the Rabi frequency of the pumping radiation.…”

“…In the absence of external light, spontaneous emission in an excited two-level atom occurs due to the fluctuations in continuum vacuum modes that play the role of a reservoir. However, when the vacuum modes are replaced with a squeezed vacuum reservoir the radiative properties of the atom are significantly modified [1][2][3][4][5][6][7][8][9][10][11][12]. It is generally found that the rate of emission is greater than that of absorption, in which the squeezed input characteristically inhibits absorption somehow and broadens the spectrum with decreasing height.…”

“…Interaction of a single two-level atom with external radiation has received a great deal of interest over the years [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. In the absence of external light, spontaneous emission in an excited two-level atom occurs due to the fluctuations in continuum vacuum modes that play the role of a reservoir.…”