One-Atom Maser

Meschede, Dieter; Walther, H.; Müller, Günter

doi:10.1103/physrevlett.54.551

Cited by 1,161 publications

(529 citation statements)

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“…On the one hand, this model is particularly interesting as it allows to theoretically study important aspects of laser physics analytically [2,3], while, on the other hand, there is great technological interest in very small tailored coherent light sources. Already two decades ago laser like systems have been set up in the microwave regime [4,5]. With the tremendous recent progress in laser cooling and micro cavity technology such systems have now indeed been experimentally realized [6,7,8,9] in the optical regime.…”

Section: Introductionmentioning

confidence: 99%

Theory of a single-atom laser including light forces

2005

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We study a single incoherently pumped atom moving within an optical high-Q resonator in the strong coupling regime. Using a semiclassical description for the atom and field dynamics, we derive a closed system of differential equations to describe this coupled atom-field dynamics. For sufficiently strong pumping the system starts lasing when the atom gets close to a field antinode, and the associated light forces provide for self-trapping of the atom. For a cavity mode blue detuned with respect to the atomic transition frequency this is combined with cavity induced motional cooling allowing for long term steady-state operation of such a laser. The analytical results for temperature and field statistics agree well with our earlier predictions based on Quantum Monte Carlo simulations. We find sub-Doppler temperatures that decrease with gain and coupling strength and can even go beyond the limit of passive cavity cooling. Besides demonstrating the importance of light forces in single-atom lasers, this result also gives strong evidence to enhance laser cooling through stimulated emission in resonators.

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Section: Introductionmentioning

confidence: 99%

Theory of a single-atom laser including light forces

2005

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“…This model can be largely handled exactly [6], even in the presence of incoherent effects like cavity damping, imperfect atom preparation, and frequency-shifting collisions. The setup has become known as the 'micromaser' because of its experimental realization with a high-quality cavity [7,8,9]. One line of research has focused on the so-called 'strong coupling regime' that permits the laser mode to be driven into non-classical states [10,11].…”

Section: Introductionmentioning

confidence: 99%

Laser theory in manifest Lindblad form

Henkel

2007

J. Phys. B: At. Mol. Opt. Phys.

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Abstract. We discuss the laser theory for a single-mode laser with nonlinear gain. We focus in particular on a micromaser which is pumped with a dilute beam of excited atoms crossing the laser cavity. In the weak-coupling regime, an expansion in the coupling strength is developed that preserves the Lindblad form of the master equation, securing the positivity of the density matrix. This expansion breaks rapidly down above threshold. This can be improved with an alternative approach, not restricted to weak coupling: the Lindblad operators are expanded in orthogonal polynomials adapted to the probability distribution for the atom-laser interaction time. Results for the photon statistics and the laser linewidth illustrate the theory.

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“…A controlled atom-cavity interaction and absence of strong statistical averaging leads to behavior foreign to conventional lasers. In this paper we report the most dramatic of these effects, the existence of multiple laser thresholds.The microlaser is the optical analogue of the micromaser [3], in which a similar bistable behavior has been observed for a single atom in the cavity [4]. The most significant differences between the two experiments are: (i) a large number of atoms is present, (ii) optical frequencies allow direct detection of generated light, and (iii) the number of thermal photons at optical frequencies is negligible.…”

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Observation of multiple thresholds in the many-atom cavity QED microlaser

Fang-Yen

et al. 2006

Phys. Rev. A

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We report the observation of multiple laser thresholds in the many-atom cavity QED microlaser. Traveling-wave coupling and a supersonic atom beam are used to create a well-defined atom-cavity interaction. Multiple thresholds are observed as jumps in photon number due to oscillatory gain. Although the number of intra-cavity atoms is large, up to N ∼ 10 3 , the dynamics of the microlaser agree with a single atom theory. This agreement is supported by quantum trajectory simulations of a many-atom microlaser and a semiclassical microlaser theory. We discuss the relation of the microlaser with the micromaser and conventional lasers.The most fundamental model of light-matter interaction at the atomic level consists of a two-level atom coupled to a single mode of the electromagnetic field, e. g. in an optical resonator. For an atom-cavity coupling strength greater than the decay rates of atom and cavity (g ≫ Γ c , Γ a ), an excited atom exchanges energy coherently with the cavity (Rabi oscillation). [1] Atom-resonator interaction is also the domain of laser physics; therefore it may be somewhat surprising that most descriptions of laser operation use an incoherent model involving population densities and Einstein A and B coefficients. Such a model applies due to gain medium broadening, laser field nonuniformity, and other statistical effects [2].The microlaser is to our knowledge the first laser in which coherent Rabi oscillation is explicitly reflected in the dynamics of the laser. A controlled atom-cavity interaction and absence of strong statistical averaging leads to behavior foreign to conventional lasers. In this paper we report the most dramatic of these effects, the existence of multiple laser thresholds.The microlaser is the optical analogue of the micromaser [3], in which a similar bistable behavior has been observed for a single atom in the cavity [4]. The most significant differences between the two experiments are: (i) a large number of atoms is present, (ii) optical frequencies allow direct detection of generated light, and (iii) the number of thermal photons at optical frequencies is negligible.An earlier version of the microlaser experiment [5] was shown to exhibit laser action with an intracavity atom number N on the order of 1. In the current setup, N ≫ 1; remarkably, the many-atom system exhibits very similar behavior to that predicted from a single atom theory. This is supported by quantum trajectory simulations and may be explained by a semiclassical theory ([6], [7]).The experiment is illustrated in Fig. 1. A supersonic beam of 138 Ba atoms passes through the TEM 00 mode of a high-finesse optical cavity (symmetric near-planar cavity, mirror separation L ≈ 0.94 mm, mirror radius of curvature r 0 = 10 cm, finesse F ≈ 9.0 × 10 5 .) The mirror separation and finesse were determined by measurement of transverse mode spacing and cavity ringdown decay time. The background pressure in the vacuum chamber is less than 10 −6 torr. Prior to entering the cavity mode, each atom is excited by a cw pump laser (Co...

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One-Atom Maser

Cited by 1,161 publications

References 12 publications

Theory of a single-atom laser including light forces

Theory of a single-atom laser including light forces

Laser theory in manifest Lindblad form

Observation of multiple thresholds in the many-atom cavity QED microlaser

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