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Atomic coherence
About: Atomic coherence is a research topic. Over the lifetime, 877 publications have been published within this topic receiving 29395 citations.
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17 Jun 2007
TL;DR: In this paper, a different scheme involving a large ensemble of Lambda-type atoms, a control field, and the field to be stored and show how to transfer with a nearly 100% efficiency a quantum state of light (squeezed vacuum) into the ground state coherence of a spin-polarized atomic cloud.
Abstract: We study here a different scheme involving a large ensemble of Lambda-type atoms, a control field, and the field to be stored and show how to transfer with a nearly 100% efficiency a quantum state of light (squeezed vacuum) into the ground state coherence of a spin-polarized atomic cloud. We find the best transfer conditions between the two oscillators. The quantum states are well conserved in two seemingly different situations: in the so-called electromagnetically-induced-transparency (EIT) situation (on one-and two-photon resonance) and in a Raman configuration (on two-photon resonance, but for large one-photon detunings). If both situations share interesting similarities in terms of transfer efficiency, and noise spectra, the physical effects responsible for the ideal mapping are quite different, and make the use of both room-temperature and cold atoms possible.
01 Jan 2012
TL;DR: In this paper, a stable Raman laser system was established for atomic coherence experiments in Rubidium 87, where two external cavity diode lasers were tuned to emit light with a wavelength around 780,241 nm.
Abstract: The aim of this project is to establish a stable Raman laser system, suitable for atomic coherence experiments in Rubidium 87. This system should be able to drive a two-photon transition between the two hyperne levels of the ground state of Rubidium 87, which can be used as qubit states for quantum information processing. Two external cavity diode lasers are tuned to emit light with a wavelength around 780,241 nm. The laser elds have a frequency dierence corresponding to a transition between the the F=1 and F=2 level of the 5S1=2 state of Rubidium 87: 6,83 GHz. Saturated absorption spectroscopy is successfully used to visualize the D2 lines of Rubidium. One of the lasers is, with the use of polarization spectroscopy in a vapor cell, locked on an atomic transition. To obtain coherence, a phase-locked loop (PLL) is used to stabilize the relative frequency and phase between the two lasers. The performance of the system is tested in an electromagnetically induced transparency experiment on Rubidium in a vapor cell. The established system shows coherence, but using the phase-feedback loop above the frequency-feedback loop does not improve the coherence of the system. The bandwidth of the PLL is too big to obtain a stable phase lock.
TL;DR: In this paper, the effect of dipole-dipole interactions for nearest neighbours in a quantum coherent system is calculated for nearest neighbors in a lattice gas approximation, and it is found that the dipole interaction is negligible for low pressure but begins to have noticeable effects on the susceptibility at a number density of about 1016 cm-3.
Abstract: In a quantum coherent system, the effect of the dipole-dipole interactions is calculated for nearest neighbours. A mean theory is used in a lattice gas approximation. It is found that the dipole interaction is negligible for low pressure but begins to have noticeable effects on the susceptibility at a number density of about 1016 cm-3.
TL;DR: In this article, the authors investigated the entanglement dynamics and coherence loss of a two-level atom dispersively interacting with two coherent fields in a dissipative cavity by using the concurrence and linear entropy, respectively.
Abstract: We investigate the entanglement dynamics and coherence loss of a two-level atom dispersively interacting with two coherent fields in a dissipative cavity by using the concurrence and linear entropy, respectively. It is shown that the atomic coherence can lead to entanglement between the atom and one mode while the two modes are always separable. We also find that there is long-lived coherence loss as the system evolves.