Steady-state superradiance with alkaline-earth-metal atoms

Meiser, Dominic; Holland, Murray

doi:10.1103/physreva.81.033847

Cited by 155 publications

(143 citation statements)

References 22 publications

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“…Furthermore, our MOT is created under conditions compatible with the creation of degenerate samples or an atom laser [7,8]. This would be the ideal source for a secondary frequency reference based on superradiant lasing, which is expected to outperform current references [9][10][11][12][13]. Our source and a future atom laser based on it might also be valuable for atomic inertial sensors [8].…”

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confidence: 99%

Steady-State Magneto-Optical Trap with 100-Fold Improved Phase-Space Density

et al. 2017

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We demonstrate a continuously loaded 88 Sr magneto-optical trap (MOT) with a steady-state phase-space density of 1.3(2) × 10 −3 . This is two orders of magnitude higher than reported in previous steady-state MOTs. Our approach is to flow atoms through a series of spatially separated laser cooling stages before capturing them in a MOT operated on the 7.4-kHz linewidth Sr intercombination line using a hybrid slower+MOT configuration. We also demonstrate producing a Bose-Einstein condensate at the MOT location, despite the presence of laser cooling light on resonance with the 30-MHz linewidth transition used to initially slow atoms in a separate chamber. Our steady-state high phase-space density MOT is an excellent starting point for a continuous atom laser and dead-time free atom interferometers or clocks.Laser cooled and trapped atoms are at the core of most ultracold quantum gas experiments [1], state-ofthe-art clocks [2] and sensors based on atom interferometry [3]. Today, these devices typically operate in a time-sequential manner, with distinct phases for sample preparation and measurement. For atomic clocks a consequence is the need to bridge the dead time between measurements using a secondary frequency reference, typically a resonator. This introduces a problem known as the Dick effect [4] in which the sampling process inherent to a clock's cyclic operation down converts or aliases high frequency noise from the secondary reference into the signal band, thus degrading performance [5]. Recently, a new generation of atomic clocks using degenerate atoms in a three-dimensional optical lattice has been demonstrated using Sr [6]. To reach the potential of such a clock, it will be necessary to overcome the Dick effect, which can be achieved by reducing the dead time and/or by creating vastly improved secondary references. Our steady-state MOT can lead to significant advances in both directions. It approaches the high flux and low temperature requirements needed for a steadystate clock, which would completely eliminate the Dick effect. Furthermore, our MOT is created under conditions compatible with the creation of degenerate samples or an atom laser [7,8]. This would be the ideal source for a secondary frequency reference based on superradiant lasing, which is expected to outperform current references [9][10][11][12][13]. Our source and a future atom laser based on it might also be valuable for atomic inertial sensors [8]. Improved clocks and inertial sensors will allow tests of fundamental physics [14] or be suitable for gravitational wave astronomy [3,[15][16][17].Over the years many creative approaches have honed laser cooling to produce pulsed samples of ever increasing phase-space density (PSD) [18][19][20][21][22][23][24][25][26][27][28][29]. Pulsed MOTs using 88 Sr have demonstrated phase-space densities of 10 −2 [30] while atoms held in dipole traps recently reached degeneracy [7,31]. Despite the exquisite performances, these techniques suffer from extremely small capture velocities.As a consequence atoms ...

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Steady-State Magneto-Optical Trap with 100-Fold Improved Phase-Space Density

et al. 2017

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“…There have also been many experimental and theoretical works studying various aspects of superradiant phenomena including correlations, pulse propagation within the ensemble, collisional dephasing of the gas molecules and polarization effects [12,13]. Of particular note is the two-time correlations within the ensemble in superradiance which have been studied extensively theoretically [11,[14][15][16][17], however have not been experimentally measured due to the difficulty in isolating two atoms in a strongly confined ensemble.…”

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confidence: 99%

Novel collective effects in integrated photonics

2012

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Superradiance, the enhanced collective emission of energy from a coherent ensemble of quantum systems, has been typically studied in atomic ensembles. In this work we study theoretically the enhanced emission of energy from coherent ensembles of harmonic oscillators. We show that it should be possible to observe harmonic oscillator superradiance for the first time in waveguide arrays in integrated photonics. Furthermore, we describe how pairwise correlations within the ensemble can be measured with this architecture. These pairwise correlations are an integral part of the phenomenon of superradiance and have never been observed in experiments to date.

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“…The potential quantumlimited linewidth of active optical clock is narrower than mHz, and it is possible to reach this unprecedented linewidth since the thermal noise of cavity mode can be reduced dramatically with the mechanism of active optical clock. It has been recognized that active optical clock has the potential to improve the stability of the best atomic clocks by about 2 orders of magnitude [9,10,15].Until now, the major experimental schemes of active optical clock are based on trapped quantum system and atomic beam quantum system. To the latter, the residual Doppler shift will be the main limitation, thus the final accuracy and stability of two-level quantum system are limited by second-order Doppler shift of thermal atomic beam.…”

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confidence: 99%

“…Since the proposal of active optical clock [1][2][3], a number of neutral atoms with two-level, three-level and four-level at thermal beam, laser cooling and trapping configurations have been investigated recently [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The potential quantumlimited linewidth of active optical clock is narrower than mHz, and it is possible to reach this unprecedented linewidth since the thermal noise of cavity mode can be reduced dramatically with the mechanism of active optical clock.…”

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Active optical clock based on four-level quantum system

et al. 2013

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Active optical clock, a new conception of atomic clock, has been proposed recently. In this work, we propose a scheme of active optical clock based on four-level quantum system. The final accuracy and stability of two-level quantum system are limited by second-order Doppler shift of thermal atomic beam. To three-level quantum system, they are mainly limited by light shift of pumping laser field. These limitations can be avoided effectively by applying the scheme proposed here. Rubidium atom four-level quantum system, as a typical example, is discussed. The population inversion between 6S 1/2 and 5P 3/2 states can be built up at a time scale of 10 −6 s. With the mechanism of active optical clock, in which the cavity mode linewidth is much wider than that of the laser gain profile, it can output a laser with quantum-limited linewidth narrower than 1 Hz in theory. An experimental configuration is designed to realize this active optical clock. Optical clocks have demonstrated great improvements in stability and accuracy over the microwave frequency standards. Since the proposal of active optical clock [1-3], a number of neutral atoms with two-level, three-level and four-level at thermal beam, laser cooling and trapping configurations have been investigated recently [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The potential quantumlimited linewidth of active optical clock is narrower than mHz, and it is possible to reach this unprecedented linewidth since the thermal noise of cavity mode can be reduced dramatically with the mechanism of active optical clock. It has been recognized that active optical clock has the potential to improve the stability of the best atomic clocks by about 2 orders of magnitude [9,10,15].Until now, the major experimental schemes of active optical clock are based on trapped quantum system and atomic beam quantum system. To the latter, the residual Doppler shift will be the main limitation, thus the final accuracy and stability of two-level quantum system are limited by second-order Doppler shift of thermal atomic beam. Laser *Corresponding author (email: ztg@pku.edu.cn) cooled and trapped quantum system provides a solution to this limitation. As for three-level quantum system, the system stability and accuracy are mainly affected by the light shift of pumping laser. Four-level quantum system can overcome these limitations and thus will be a better choice for active optical clock with improved performance [6].Rubidium, as one of alkali metals, has been investigated as the critical research atom of Bose-Einstein condensate, photonic Josephson effect, fractionalized vortices in lattice due to the mature technique of laser cooling and trapping [16][17][18].We have investigated several alkali metals including potassium, rubidium and cesium and found that the four-level quantum systems of these elements are appropriate choices based on the mechanism of active optical clock. Here we take rubidium atom as an example. The population inversion can be realized as shown in Figure 1.A 421.7 nm las...

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Steady-state superradiance with alkaline-earth-metal atoms

Cited by 155 publications

References 22 publications

Steady-State Magneto-Optical Trap with 100-Fold Improved Phase-Space Density

Steady-State Magneto-Optical Trap with 100-Fold Improved Phase-Space Density

Novel collective effects in integrated photonics

Active optical clock based on four-level quantum system

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