Intensity fluctuations in steady-state superradiance

Meiser, Dominic; Holland, Murray

doi:10.1103/physreva.81.063827

Cited by 122 publications

(201 citation statements)

References 26 publications

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“…As we increase I p , g (2) s,i (0) (τ c ) increases (decreases) and approaches a value of 2 (50 µs). This behavior is consistent with recent predictions on steady-state superradiance [1], where b) The degree of second-order coherence g (2) s (τ ) for the signal beam time series shown in a). We find that g (2) s ( the system transitions from the superradiant to thermal regime with stronger pumping.…”

supporting

confidence: 78%

“…While one might expect random scattering from the MOT beams to inhibit atomic self-organization, we find instead only a slight reduction in the amplitude and degree of correlation (r s,i (0) ∼ 0.8) of the generated light compared to the case of fully-extinguished MOT fields. This situation is analogous to a recently-demonstrated scheme for steady-state superradiance based on the rapid repopulation of a long-lived excited state [29,30]. Rather than employing internal states, we use long-lived centerof-mass states and continuously drive atomic bunching more rapidly than the superradiant emission rate.…”

mentioning

confidence: 99%

“…This system therefore has applications in fundamental studies of many-body physics with long-range interactions as well as all-optical and quantum information processing. The study of collective light-matter interactions, where the dynamics of an individual scatterer depend on the state of the entire multi-scatterer system, has recently received much attention in the areas of fundamental research and photonic technologies [1,2]. One prominent example of collective behavior is superradiance [3], where light-induced couplings between initially incoherentlyprepared emitters cause the full ensemble to synchronize and radiate coherently [4].…”

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Steady-state, cavityless, multimode superradiance in a cold vapor

Greenberg

Gauthier

2012

Phys. Rev. A

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We demonstrate steady-state, mirrorless superradiance in a cold vapor pumped by weak optical fields. Beyond a critical pump intensity of 1 mW/cm 2 , the vapor spontaneously transforms into a spatially self-organized state: a density grating forms. Scattering of the pump beams off this grating generates a pair of new, intense optical fields that act back on the vapor to enhance the atomic organization. We map out experimentally the superradiant phase transition boundary and show that it is well-described by our theoretical model. The resulting superradiant emission is nearly coherent, persists for several seconds, displays strong temporal correlations between the various modes, and has a coherence time of several hundred µs. This system therefore has applications in fundamental studies of many-body physics with long-range interactions as well as all-optical and quantum information processing. The study of collective light-matter interactions, where the dynamics of an individual scatterer depend on the state of the entire multi-scatterer system, has recently received much attention in the areas of fundamental research and photonic technologies [1,2]. One prominent example of collective behavior is superradiance [3], where light-induced couplings between initially incoherentlyprepared emitters cause the full ensemble to synchronize and radiate coherently [4]. While early studies of superradiance focused on collective scattering via the emitters' internal degrees of freedom, recent work demonstrates that formally identical behavior arises through the manipulation of the center-of-mass positions and momenta of cold atoms [5][6][7].In these studies, an initially uniformly-distributed gas of atoms pumped by external optical fields spontaneously undergoes a transition to a spatially-ordered state under certain circumstances [5][6][7][8]. This ordering arises from the momentum imparted to the atoms via optical scattering and can be understood as a form of atomic synchronization: instead of the atoms scattering light individually, the self-assembled density grating enables the entire ensemble to coherently scatter light as a single entity. The pump beams scatter off this grating and produce new optical fields that act back on the vapor to enhance the grating contrast. This emergent, dynamical organization can lead to reduced optical instability thresholds [9] and new phenomena [10] that are inaccessible using static, externally-imposed optical lattices [11].In order for superradiance to occur, the system must posses sufficient gain and feedback so that synchronization occurs more rapidly than dephasing. The main dephasing mechanisms are grating washout due to thermal atomic motion and the loss of photons from the interaction volume [5]. One can overcome the effects of thermal motion in free space by working at ultracold temperatures (T < 3 µK) and using optical fields detuned far from the atomic resonance in order to avoid recoilinduced heating [8,12]. Multi-mode superradiance has been observed in such systems [8], althou...

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confidence: 78%

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confidence: 99%

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confidence: 99%

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Steady-state, cavityless, multimode superradiance in a cold vapor

Greenberg

Gauthier

2012

Phys. Rev. A

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“…This may enable future advances in quantum metrology, in non-linear photon interactions [43][44][45], and in the generation of entanglement for advancing optical lattice clocks [15][16][17]. Further, by strongly coupling a narrow transition to a more highly damped optical cavity (κ γ), the rate at which information can be extracted is greatly increased.…”

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confidence: 99%

Strong coupling on a forbidden transition in strontium and nondestructive atom counting

Norcia

Thompson

2016

Phys. Rev. A

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We observe strong collective coupling between an optical cavity and the forbidden spin singlet to triplet optical transition 1 S0 to 3 P1 in an ensemble of 88 Sr. Despite the transition being 1000 times weaker than a typical dipole transition, we observe a well resolved vacuum Rabi splitting. We use the observed vacuum Rabi splitting to make non-destructive measurements of atomic population with the equivalent of projection-noise limited sensitivity and minimal heating (< 0.01 photon recoils/atom). This technique may be used to enhance the performance of optical lattice clocks by generating entangled states and reducing dead time.Two modes are strongly coupled when the frequency Ω at which they exchange excitations exceeds the rate of interaction with the environment. Strong coupling enables one to generate large amounts of entanglement [1, 2], achieve efficient quantum memories [3], cool the motion of atoms [4] and mesoscopic oscillators [5], and explore collective self-organization and synchronization phenomena such as superradiant lasing [6][7][8][9] and the Dicke phase transition [10,11].In this Letter, we observe strong coupling between an optical cavity and the collective excitation of up to N = 1.25 × 10 5 strontium atoms in a 1D optical lattice. The strong coupling is achieved using the forbidden electronic spin singlet to triplet optical transition 1 S 0 to 3 P 1 in 88 Sr. The excited state 3 P 1 couples to the environment via spontaneous emission at the relatively slow rate of γ = 2π × 7.5 kHz.Despite operating on a transition with 1000 times smaller squared matrix element than transitions typically used in optical cavity-QED experiments, we observe a highly-resolved splitting of the normal modes of the coupled atom-cavity system, known as a collective vacuum Rabi splitting [12,13]. This observation demonstrates that despite the relative feebleness of the transition, the tools of cavity-QED can now be applied to a system of extreme interest for quantum metrology [14]. Example technologies include optical lattice clocks [15][16][17] and ultra-narrow lasers [6][7][8][9], along with their associated broad range of potential applications such defining the second [14,18], quantum many-body simulations [19], measuring gravitational potentials [20] and gravity waves [21], and searches for physics beyond the standard model [22,23].One relevant application of this newly achieved regime is for state-selective, non-destructive counting of strontium atoms. Such counting has been used to generate highly spin-squeezed states [1,24] that surpass the standard quantum limit on phase estimation [25][26][27]. More simply, but quite importantly, non-destructive readout methods [28] can reduce the highly deleterious effects of local oscillator noise aliasing [29,30] in optical lattice clocks. Here, we utilize the observed vacuum Rabi splitting to non-destructively count atoms with the equivalent of sub-projection noise sensitivity. We verify that this sensitivity is achieved with as few as 0.01 photon recoils imparted to e...

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“…We consider the synchronization of two active atomic clocks coupled to a common single-mode optical cavity. It has been predicted that in the regime of steady-state superradiance [21][22][23][24] a neutral atom lattice clock could produce an ultracoherent optical field with a quality factor (ratio of frequency to linewidth) that approaches 10 18 . We show that two such clocks may exhibit a dynamical phase transition [26][27][28][29] from two disparate oscillators to quantum phase-locked dynamics.…”

mentioning

confidence: 99%

Synchronization of Two Ensembles of Atoms

Xu¹,

Tieri²,

Fine³

et al. 2014

Phys. Rev. Lett.

201

206

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We propose a system for observing the correlated phase dynamics of two mesoscopic ensembles of atoms through their collective coupling to an optical cavity. We find a dynamical quantum phase transition induced by pump noise and cavity output-coupling. The spectral properties of the superradiant light emitted from the cavity show that at a critical pump rate the system undergoes a transition from the independent behavior of two disparate oscillators to the phase-locking that is the signature of quantum synchronization. PACS numbers: 05.45.Xt, 42.50.Lc, 37.30.+i, 64.60.Ht Synchronization is an emergent phenomenon that describes coupled objects spontaneously phase-locking to a common frequency in spite of differences in their natural frequencies [1]. It was famously observed by Huygens, the seventeenth century clock maker, in the antiphase synchronization of two maritime pendulum clocks [2]. Dynamical synchronization is now recognized as ubiquitous behavior occurring in a broad range of physical, chemical, biological, and mechanical engineering systems [1,3,4].Theoretical treatments of this phenomenon are often based on the study of phase models [5,6], and as such have been applied to an abundant variety of classical systems, including the collective blinking of fireflies, the beating of heart cells, and audience clapping. The concept can be readily extended to systems with an intrinsic quantum mechanical origin such as nanomechanical resonators [7,8], optomechanical arrays [9], and Josephson junctions [10,11]. When the number of coupled oscillators is large, it has been demonstrated that the onset of classical synchronization is analogous to a thermodynamic phase transition [12] and exhibits similar scaling behavior [13].Recently, there has been increasing interest in exploring manifestations in the quantum realm. Small systems have been considered, e.g., one qubit [14] and two qubits [15] coupled to a quantum dissipative driven oscillator, two dissipative spins [16], two coupled cavities [17], and two micromechanical oscillators [18,19]. Connections between quantum entanglement and synchronization have been revealed in continuous variable systems [19]. It has been shown that quantum synchronization may be achieved between two canonically conjugate variables [20]. Since the phenomenon is inherently non-equilibrium, all of these systems share the common property of competition between coherent and incoherent driving and dissipative forces.In this paper, we propose a modern-day realization of the original Huygens experiment [2]. We consider the synchronization of two active atomic clocks coupled to a common single-mode optical cavity. It has been predicted that in the regime of steady-state superradiance [21-24] a neutral atom lattice clock could produce an ultracoherent optical field with a quality factor (ratio of frequency to linewidth) that approaches 10 18 . We show that two such clocks may exhibit a dynamical phase transition [26][27][28][29] from two disparate oscillators to quantum phase-locked dynamics. ...

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Intensity fluctuations in steady-state superradiance

Cited by 122 publications

References 26 publications

Steady-state, cavityless, multimode superradiance in a cold vapor

Steady-state, cavityless, multimode superradiance in a cold vapor

Strong coupling on a forbidden transition in strontium and nondestructive atom counting

Synchronization of Two Ensembles of Atoms

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