Cavity-immune spectral features in the pulsed superradiant crossover regime

Tang, Mikkel; Schäffer, Stefan A.; Jørgensen, Asbjørn A.; Henriksen, Martin R.; Christensen, Bjarke T. R.; Müller, J. H.; Thomsen, J.

doi:10.1103/physrevresearch.3.033258

Cited by 12 publications

(7 citation statements)

References 29 publications

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“…As already discovered in the early days of quantum optics, the generalized cumulant expansion approach works well in open-system problems such as lasing [15,16]. In the recent renewed interest in so-called superradiant lasers, where large ensembles of particles interact via a single cavity mode, the method was extensively used with notable success [17,18,19,20,21,22,23,24,25,26]. Furthermore, not only cavity QED systems have been calculated, but also ensembles of interacting free-space atoms, pointing out the importance of higher orders in specific cases [27,28,29].…”

Section: Introductionmentioning

confidence: 99%

QuantumCumulants.jl: A Julia framework for generalized mean-field equations in open quantum systems

Plankensteiner

Hotter

Ritsch

2022

Quantum

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A full quantum mechanical treatment of open quantum systems via a Master equation is often limited by the size of the underlying Hilbert space. As an alternative, the dynamics can also be formulated in terms of systems of coupled differential equations for operators in the Heisenberg picture. This typically leads to an infinite hierarchy of equations for products of operators. A well-established approach to truncate this infinite set at the level of expectation values is to neglect quantum correlations of high order. This is systematically realized with a so-called cumulant expansion, which decomposes expectation values of operator products into products of a given lower order, leading to a closed set of equations. Here we present an open-source framework that fully automizes this approach: first, the equations of motion of operators up to a desired order are derived symbolically using predefined canonical commutation relations. Next, the resulting equations for the expectation values are expanded employing the cumulant expansion approach, where moments up to a chosen order specified by the user are included. Finally, a numerical solution can be directly obtained from the symbolic equations. After reviewing the theory we present the framework and showcase its usefulness in a few example problems.

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Section: Introductionmentioning

confidence: 99%

QuantumCumulants.jl: A Julia framework for generalized mean-field equations in open quantum systems

Plankensteiner

Hotter

Ritsch

2022

Quantum

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“…These studies are also fueled by the remarkable operating characteristics and relative simplicity of its microwave analogue, the hydrogen maser [11,12]. Recently pulsed superradiance has been experimentally observed using laser-cooled atomic ensembles [13][14][15]. Some proof of principle setups based on magneto-optical trapping demonstrated quasi-continuous operation on kHz transitions [16,17].…”

Section: Introductionmentioning

confidence: 99%

A superradiant two-level laser with intrinsic light force generated gain

Bychek,

Ritsch

2023

New J. Phys.

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The implementation of a superradiant laser as an active frequency standard is predicted to provide better short-term stability and robustness to thermal and mechanical fluctuations when compared to standard passive optical clocks. However, despite significant recent progress, the experimental realization of continuous wave superradiant lasing still remains an open challenge as it requires continuous loading, cooling, and pumping of active atoms within an optical resonator. Here we propose a new scenario for creating continuous gain by using optical forces acting on the states of a two-level atom via bichromatic coherent pumping of a cold atomic gas trapped inside a single-mode cavity. Analogous to atomic maser setups, tailored state-dependent forces are used to gather and concentrate excited state atoms in regions of strong atom-cavity coupling while ground-state atoms are repelled. To facilitate numerical simulations of a sufficiently large atomic ensemble, we rely on a second-order cumulant expansion and describe the atomic motion in a semi-classical point-particle approximation subject to position-dependent light shifts which induce optical gradient forces along the cavity axis. We study minimal conditions on pump laser intensities and detunings required for collective superradiant emission. Balancing Doppler cooling and gain-induced heating we identify a parameter regime of a continuous narrow-band laser operation close to the bare atomic frequency.

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“…It is well established that inverting all atoms with a short π-pulse induces the emission of a delayed intense light pulse due to cavity enhanced superradiant decay [17][18][19][20][21][22]. Synchronized stimulated emission in a cavity occurs even for a dilute ensemble, which does not exhibit free space superradiance.…”

Section: Introductionmentioning

confidence: 99%

Cavity Sub- and Superradiance Enhanced Ramsey Spectroscopy

Hotter¹,

Ostermann²,

Ritsch³

2022

Preprint

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Ramsey spectroscopy in large, dense ensembles of ultra-cold atoms trapped in optical lattices suffers from dipole-dipole interaction induced shifts and collective superradiance limiting its precision and accuracy. We propose a novel geometry implementing fast signal readout with minimal heating for large atom numbers at lower densities via an optical cavity operated in the weak single atom but strong collective coupling regime. The key idea is controlled collective transverse π/2-excitation of the atoms to prepare a macroscopic collective spin protected from cavity superradiance. This requires that the two halves of the atomic ensemble are coupled to the cavity mode with opposite phase, which is naturally realized for a homogeneously filled volume covering odd and even sites of the cavity mode along the cavity axis. The origin of the superior precision can be traced back to destructive interference among sub-ensembles in the complex nonlinear collective atom field dynamics.In the same configuration we find surprising regular self-pulsing of the cavity output for suitable continuous illumination. Our simulations for large atom numbers employing a cumulant expansion are qualitatively confirmed by a full quantum treatment of smaller ensembles.

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Cavity-immune spectral features in the pulsed superradiant crossover regime

Cited by 12 publications

References 29 publications

QuantumCumulants.jl: A Julia framework for generalized mean-field equations in open quantum systems

QuantumCumulants.jl: A Julia framework for generalized mean-field equations in open quantum systems

A superradiant two-level laser with intrinsic light force generated gain

Cavity Sub- and Superradiance Enhanced Ramsey Spectroscopy

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