Generic model of an atom laser

Kneer, B.; Wong, Thomas G.; Vogel, Karl; Schleich, W. P.; Walls, D. F.

doi:10.1103/physreva.58.4841

Cited by 76 publications

(77 citation statements)

References 62 publications

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“…Our model is inspired by classical treatments of laser operation [9], and closely resembles the generic model of atom lasers developed in [10]. In this way, we are able not only to confirm the conclusions of Ref.…”

supporting

confidence: 74%

“…The first + branch of (8) is the Goldstone branch which corresponds for small k values to a slow rotation of the condensate phase, while the − branch corresponds to slow modulations of the condensate density; for low k values, these are damped at the finite rate Γ defined in (10). From (8) it is immediate to obtain a prediction for the width ∆k of the region in k space in which the dispersion of the Goldstone mode is flat Re[ω G (k)] = 0.…”

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confidence: 99%

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Excitations in a Nonequilibrium Bose-Einstein Condensate of Exciton Polaritons

2007

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We have developed a mean-field model to describe the dynamics of a non-equilibrium BoseEinstein condensate of exciton-polaritons in a semiconductor microcavity. The spectrum of elementary excitations around the stationary state is analytically studied in different geometries. A diffusive behaviour of the Goldstone mode is found in the spatially homogeneous case and new features are predicted for the Josephson effect in a two-well geometry. [4,5]. The system under investigation consists of a semiconductor microcavity containing a few quantum wells with an excitonic transition strongly coupled to the cavity photon mode. In this strong coupling regime, the basic excitations of the system are excitonpolaritons, i.e. linear superpositions of a quantum well exciton and a cavity photon. As compared to other examples of BEC, namely in liquid 4 He and ultracold atomic gases, the main novelty of the present polariton system is its intrinsic non-equilibrium nature due to the finite lifetime of polaritons. The condensate has in fact to be continuously replenished from the relaxation of optically injected high energy excitations (e.g. free carriers or hot polaritons), and its steady state results from a dynamical equilibrium between pumping and losses. This makes the present system a unique candidate for the study of the BEC phase transition in a non-equilibrium context. Recent theoretical work [6] has suggested that the non-equilibrium condition is responsible for dramatic changes in the dispersion of low-lying excitations of incoherently pumped polariton condensates: the sound mode of equilibrium condensates is replaced by a diffusive mode with flat dispersion, as it typically happens in coherently driven pattern forming systems, such as Benard cells in heat convection [7] or optical parametric oscillators [8].The present Letter is devoted to the development of a simple and generic model of a non-equilibrium condensate which does not involve the microscopic physics of the polariton, and can be used to describe the dynamics independently of the details of the specific pumping scheme. Our model is inspired by classical treatments of laser operation [9], and closely resembles the generic model of atom lasers developed in [10]. In this way, we are able not only to confirm the conclusions of Ref.[6] but also to analytically relate the elementary excitation spectrum to experimentally accessible quantities. The same model is then applied to the Josephson effect [11,12,13] in a system of two weakly coupled polaritonic condensates: predictions are given for the frequency and the intrinsic damping rate of Josephson oscillations, and overdamped behavior is anticipated in the case of strong damping.The experimental scheme used to create the polariton condensate is sketched in Fig.1a: under a continuouswave high energy illumination, hot free carriers are generated in the semiconductor material forming the microcavity. Their cooling down by phonon emission leads the formation of a incoherent gas of bound excitons in the quantum wells, ...

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confidence: 74%

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confidence: 99%

Excitations in a Nonequilibrium Bose-Einstein Condensate of Exciton Polaritons

2007

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“…Corresponding experiments will be discussed in the following section. There have been many theoretical investigations on the physics of the output mechanism and the resulting matter wave field outside the trap [141,142,143,132,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162]. The internal degrees of freedom and their coherent manipulation with external fields opens more possibilities for this process than the optical analogue of tunneling through a potential barrier.…”

Section: Ideas and Concepts Of Atom Lasersmentioning

confidence: 99%

Physics with coherent matter waves

Bongs¹,

Sengstock²

2004

Rep. Prog. Phys.

178

190

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Abstract. This review discusses progress in the new field of coherent matter waves, in particular with respect to Bose-Einstein condensates. We give a short introduction to Bose-Einstein condensation and the theoretical description of the condensate wavefunction. We concentrate on the coherence properties of this new type of matter wave as a basis for fundamental physics and applications. The main part of this review treats various measurements and concepts in the physics with coherent matter waves. In particular we present phase manipulation methods, atom lasers, nonlinear atom optics, optical elements, interferometry and physics in optical lattices. We give an overview of the state of the art in the respective fields and discuss achievements and challenges for the future. § To whom correspondence should be addressed (sengstock@physnet.uni-hamburg.de) Physics with coherent matter waves 2

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“…They determined that, as the condensate grows, the center of mass oscillates in the trap. Furthermore, GP gain equation is of special importance in the field of an atom laser, that is a device which produces an intense coherent beam of atoms by a stimulated process [12,13]. In recent years, GP gain equation (1) has also been studied mathematically by some authors [14,15,16].…”

Section: Introductionmentioning

confidence: 99%