Observation of superfluorescence from a quantum ensemble of coherent excitons in a ZnTe crystal: Evidence for spontaneous Bose-Einstein condensation of excitons

Dai, De-Chang; Monkman, A. P.

doi:10.1103/physrevb.84.115206

Cited by 50 publications

(46 citation statements)

References 46 publications

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“…(Here the term "superfluorescence" is used instead of the more common term "SR" because in many experimental and theoretical works the latter implies that there is some preliminary coherent resonant pulse initiating a collective spontaneous emission.) Similar observations are made for the superfluorescent recombination in semiconductor samples with modest inhomogeneous broadening of active particles, which include free electrons and holes in magnetized GaAs quantum wells [21,22], degenerate electronhole gas in semiconductors [29], excitons in ZnTe crystals [10,34], and In-centers in Cd 0.8 Zn 0.2 T e crystals [13]. Based on CW pumping, the class D lasers are expected [31] to have variety of operation regimes, rich multi-mode spectra, and flexible pulse profiles, which are promising for the pulse shaping technologies and the pulse processing in "information optics" [18,39,45].…”

Section: Two Types Of Media With Extreme Spatial-spectral Density Of supporting

confidence: 56%

Superradiant Lasing and Collective Dynamics of Active Centers with Polarization Lifetime Exceeding Photon Lifetime

Kocharovskaya¹,

Kocharovsky²

2015

Springer Series in Optical Sciences

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Analytic theory, numerical simulation, and qualitative analysis of the threshold conditions, nonlinear dynamics, and spectral features of the superradiant emission and cooperative radiative behavior of a dense many-particle system in a low-Q Fabry-Perot cavity with distributed feedback of counter-propagating electromagnetic waves are given. Various systems with extreme spatial-spectral density of radiating particles as active media of superradiant lasers are discussed, including those with almost homogeneous broadening as well as strongly inhomogeneous broadening of a spectral line. In the case of experimental verification, the phenomenon of CW superradiant lasing will be promising in the information optoelectronics and condensed matter physics, in particular, for managing novel oscillators with complicated dynamical spectra and for creating unprecedented diagnostics of quantum coherent many-particle effects. Introduction. What is a class D laser?Recent experiments on pulsed superfluorescence and prospects of CW superradiant lasing in various active media (see Sect. 4.2) require a systematic analysis of the threshold conditions and the non-stationary regimes of a cooperative emission based on mode superradiance (SR). This emission takes place in the case when a photon lifetime is much shorter than a polarization lifetime of an active center. The latter situation means a low-Q cavity and a dense active medium and corresponds to the so-called class D lasers [6,28], which differ in many respects from the standard lasers of A, B, and C classes introduced by Arecchi and Harrison [3].The key difference is related to the collective dynamics of the active centers which totally alters the dynamical spectra of their population inversion and cavity Vl. V. Kocharovsky ( ) · V. V. Kocharovsky · E. R. Kocharovskaya IAP RAS, 46, Ulyanov str.,

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Section: Two Types Of Media With Extreme Spatial-spectral Density Of supporting

confidence: 56%

Superradiant Lasing and Collective Dynamics of Active Centers with Polarization Lifetime Exceeding Photon Lifetime

Kocharovskaya¹,

Kocharovsky²

2015

Springer Series in Optical Sciences

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“…It has also been suggested that Bose-Einstein condensation of excitons may increase the coherence area and the resulting decay rate [126,127].…”

Section: A Excitonic Superradiance In Semiconductormentioning

confidence: 99%

Dicke superradiance in solids [Invited]

et al. 2016

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Recent advances in optical studies of condensed matter systems have led to the emergence of a variety of phenomena that have conventionally been studied in the realm of quantum optics. These studies have not only deepened our understanding of light-matter interactions but also introduced aspects of many-body correlations inherent in optical processes in condensed matter systems. This article is concerned with the phenomenon of superradiance (SR), a profound quantum optical process originally predicted by Dicke in 1954. The basic concept of SR applies to a general N -body system where constituent oscillating dipoles couple together through interaction with a common light field and accelerate the radiative decay of the whole system. Hence, the term SR ubiquitously appears in order to describe radiative coupling of an arbitrary number of oscillators in many situations in modern science of both classical and quantum description. In the most fascinating manifestation of SR, known as superfluorescence (SF), an incoherently prepared system of N inverted atoms spontaneously develops macroscopic coherence from vacuum fluctuations and produces a delayed pulse of coherent light whose peak intensity ∝ N 2 . Such SF pulses have been observed in atomic and molecular gases, and their intriguing quantum nature has been unambiguously demonstrated. In this review, we focus on the rapidly developing field of research on SR phenomena in solids, where not only photon-mediated coupling (as in atoms) but also strong Coulomb interactions and ultrafast scattering processes exist. We describe SR and SF in molecular centers in solids, molecular aggregates and crystals, quantum dots, and quantum wells. In particular, we will summarize a series of studies we have recently performed on semiconductor quantum wells in the presence of a strong magnetic field. In one type of experiment, electron-hole pairs were incoherently prepared, but a macroscopic polarization spontaneously emerged and cooperatively decayed, emitting an intense SF burst. In another type of experiment, we observed the SR decay of coherent cyclotron resonance of ultrahigh-mobility two-dimensional electron gases, leading to a decay rate that is proportional to the electron density. These results show that cooperative effects in solid-state systems are not merely small corrections that require exotic conditions to be observed; rather, they can dominate the nonequilibrium dynamics and light emission processes of the entire system of interacting electrons.

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“…The importance of coherent population gratings for the generation of SR emission in semiconductor structures has not been understood in previous studies [5][6][7]22]. Here, we point out two issues which have been clarified during the present work.…”

Section: Discussionmentioning

confidence: 71%

“…Various papers have reported SR phenomena in semiconductors at room temperature [22][23][24][25]. Such observations however have led to debate on whether the pulses generated are really akin to those superradiant phenomena observed in low temperature or low density structures [5][6][7], and whether they are different, for example, than those generated by conventional Qswitching [26]. In this work, therefore, by measuring the superluminal propagation properties of the pulses generated in GaAs/AlGaAs multiple contact heterostructures operating in a superradiant emission regime, we demonstrate for the first time the clear existence of transient coherent gratings directly coupled to the amplified pulses.…”

Section: Introductionmentioning

confidence: 99%

Pulse generation with ultra-superluminal pulse propagation in semiconductor heterostructures by superradiant-phase transition enhanced by transient coherent population gratings

2016

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This paper reports the observation of ultra-superluminal pulse propagation in multiple-contact semiconductor heterostructures in a superradiant emission regime, and shows definitively that it is a different class of emission from conventional spontaneous or stimulated emission. Coherent population gratings induced in the semiconductor medium under strong electrical pumping have been shown to cause a major decrease of the group refractive index, in the range of 5–40%. This decrease is much greater than that caused by conventional carrier depletion or chirp mechanisms. The decrease in refractive index in turn causes faster-than-c propagation of femtosecond pulses. The measurement also proves the existence of coherent amplification of electromagnetic pulses in semiconductors at room temperature, the coherence being strongly enhanced by interactions of the light with coherent transient gratings locked to carrier gratings. This pulse-generation technique is anticipated to have great potential in applications where highly coherent femtosecond optical pulses must be generated on demand.

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Observation of superfluorescence from a quantum ensemble of coherent excitons in a ZnTe crystal: Evidence for spontaneous Bose-Einstein condensation of excitons

Cited by 50 publications

References 46 publications

Superradiant Lasing and Collective Dynamics of Active Centers with Polarization Lifetime Exceeding Photon Lifetime

Superradiant Lasing and Collective Dynamics of Active Centers with Polarization Lifetime Exceeding Photon Lifetime

Dicke superradiance in solids [Invited]

Pulse generation with ultra-superluminal pulse propagation in semiconductor heterostructures by superradiant-phase transition enhanced by transient coherent population gratings

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