Atomic coherence

About: Atomic coherence is a research topic. Over the lifetime, 877 publications have been published within this topic receiving 29395 citations.

Dressed-state analysis of efficient three-dimensional atom localization in a ladder-type three-level atomic system

Abstract: We study the control of high-precision three-dimensional (3D) atom localization by measuring the population of the excited state in a ladder-type three-level atomic system driven by a weak probe field and a control field, together with three mutually perpendicular standing-wave fields. We find that the precision of 3D atom localization in volumes depends sensitively on the frequency detuning of the probe field and the intensity of the control field. Most importantly, we show that adjusting the phase shifts associated with the standing-wave fields leads to a redistribution of the atoms and a significant change of the atomic coherence, so that the atom can be localized in volumes that are substantially smaller than a cubic optical wavelength.

Dispersive switching in mesoscopic multistable systems

Abstract: Dispersive switching effect is examined for a mesoscopic system of coherently injected two-level Rydberg atoms into a driven single-mode superconducting cavity. The effect concerns the switching of the output field by simultaneously varying the atomic and cavity detuning parameters at fixed values of the coherent driving field. For certain atomic coherence parameters, symmetric and asymmetric switching diagrams are exhibited, which include one- and two-way process via multistep transitions between output field states.

Reading the phase of a Raman excitation with a multi-state atomic interferometer

Abstract: Atomic memories for flying photonic qubits are an essential ingredient for many applications like e.g. quantum repeaters. Verification of the coherent transfer of information from a light field to an atomic superposition is usually obtained using an optical read-out. In this paper we report the direct detection of the atomic coherence by means of atom interferometry. We experimentally verified both that a bichromatic laser field closing a Raman transition imprints a distinct, controllable phase on the atomic coherence and that it can be recovered after a variable time delay.

Slow Light by Modified Reservoir Induced Transparency with a Non-Singular Density of Modes

Abstract: We investigate the dispersive property of a ?-type atomic system embedded in photonic band gap structures. The atomic coherence is established by the structured reservoir which consists of a double-band photonic band gap (PBG) and defect modes. With an atomic density of 7?1015?atoms/cm3, the group velocity of a probe laser being detuned far away from the gap is shown to be reduced to 3?102?m/s near the transparency window associated with the PBG edges and 6?103?m/s at the transparency window associated with the defect modes, without using any deriving field. The influence of the smoothness of the density of modes and the decay rate of the second ground state of atoms are analysed.

Nonlinear theory of a laser with injected atomic coherence.

Abstract: The influence of injected atomic coherence on a laser's operation is discussed by analyzing the semiclassical equations of motion of this system. Both stationary-steady-state and time-dependent regimes of operation are investigated. We present the dependence of the stationary laser intensity and phase on the external parameters (population inversion, amplitude of atomic coherence, and detuning). For small cavity-field detuning and large atomic coherence, both frequency and phase locking occurs. The laser frequency is locked to the atomic frequency, and the phase is locked to a value determined primarily by the phase of the atomic coherence. Under certain conditions, in the inverted regime, the output intensity is an ssS-shaped function of the atomic coherence, leading to the possibility of a bistable behavior. However, only a portion of the bistable curve gives stable stationary operation, and in critical points (the location of which depends crucially on the external parameters) time-dependent instabilities branch away. When the detuning is larger than a critical value there is neither phase nor frequency locking. We find that the time-dependent behavior of the laser intensity in this case is oscillatory (quasiperiodic), and show that there is a stable limit cycle in the phase plane of the quadratures. There is a small parameter region where a stationary steady state and an oscillatory state may coexist. We also consider the nonlinear quantum theory of a laser with injected atomic coherence, and include the effect of pumping statistics. We derive the Fokker-Planck equation for the P representation, and express the noise in terms of moments. We find that in the steady state the intensity noise can be suppressed below the shot-noise limit but that the phase fluctuations are not affected by pump regularity. For nonzero detuning, we find that transient squeezing of the phase fluctuations is possible.