Quantum fluctuations of a single trapped atom: transient Rabi oscillations and magnetic bistability

Abstract

Isolation of a single atomic particle and monitoring its resonance fluorescence is a powerful tool for studies of quantum effects in radiationmatter interaction. Here we present observations of quantum dynamics of an isolated neutral atom stored in a magneto-optical trap. By means of photon correlations in the atom's resonance fluorescence we demonstrate the well-known phenomenon of photon antibunching which corresponds to transient Rabi oscillations in the atom. Through polarization-sensitive photon correlations we show a novel example of resolved quantum fluctuations: spontaneous magnetic orientation of an atom. These effects can only be observed with a single atom. keywords: laser cooling and trapping, single atoms, photon correlations, quantum fluctuations

A single trapped atom: Light‐matter interaction at the microscopic level

“…Thus for our experiment we must acknowledge that the observation of a circularly polarized photon not only redefines atomic orientation but also its mechanical status: Internal and external atomic degrees of freedom are inextricably entangled. In a more detailed investigation we have measured that the correlation relaxation rate is indeed proportional to the average atomic velocity [23]. This indicates that relaxation of the bistable atomic magnetization is caused by atomic motion through the light field.…”

“…In one dimension two counter propagating circularly polarized laser beams with the same handedness (σ + σ − configuration) produce a light field with linear polarization everywhere. A threedimensional analogue is obtained for a variant of the MOT with a special configuration of light fields with full phase control [21][22][23]. The 1dconfiguration is nevertheless a reasonable model for 3d since an atom diffusing through this field is essentially subject to a linear polarization which changes direction by a full turn every wavelength and in every direction.…”

The resonance fluorescence cascade of a laser-excited two-level atom

“…We now discuss the photon-correlation signal that has been studied theoretically [17][18][19][20] and experimentally [12,13]. This correlation reveals the antibunching effect that has been used as a characterization tool for a large variety of systems of physical interest [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58].…”

Essential structure in physical observation

“…. "Photon anti bunching" -fast non-local negative correlation as observed when the coupling modes are filtered through a single trapped atom (Schadwinkel et al, 2000(Schadwinkel et al, , p. 1359).…”