Biexcitonic superfluorescence from CuCl quantum dots under resonant two‐photon excitation

Miyajima, Kensuke; Maeno, K.; Saito, Shingo; Ashida, Masaaki; Itoh, Tadashi

doi:10.1002/pssc.201000668

Cited by 9 publications

(5 citation statements)

References 13 publications

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“…The SF from biexcitons, which are bound two-exciton pairs, in CuCl QDs was reported in our previous papers. − On the contrary, for the excitons, the SF was not observed because of a reabsorption process. The resonant two-photon excitation of biexcitons is useful for establishing complete population inversion between the biexciton and exciton states as an initial population state because the excitation photon energy is lower than the exciton energy.…”

Section: Introductionmentioning

confidence: 57%

“…28 In addition, this ultrashort pulsed SF exhibited a blue shift in the peak energy with the increase an excitation density. 29 From these results, we suggest that the SF generation efficiency is related to the dot-size-dependent properties, e.g., radiative time. The subpicosecond excitation pulse resulted in short pulsed SF, but the influence of a large spectral width on SF generation has not yet been revealed.…”

Section: ■ Introductionmentioning

confidence: 74%

“…As a result, we suggest that ultrashort pulsed SF appeared only under two conditions: initial complete population inversion between the biexciton and exciton states and simultaneous excitation of the QD assembly with inhomogeneously broadened spectral width . In addition, this ultrashort pulsed SF exhibited a blue shift in the peak energy with the increase an excitation density . From these results, we suggest that the SF generation efficiency is related to the dot-size-dependent properties, e.g., radiative time.…”

Section: Introductionmentioning

confidence: 77%

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Ultrashort Radiation of Biexcitonic Superfluorescence from High-Density Assembly of Semiconductor Quantum Dots

2017

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High-density semiconductor quantum dot (QD) assembly is a promising system to generate ultrashort radiation of superfluorescence (SF) which is a cooperative emission of many coherent excited particles induced by an interaction with a resonant radiation field. In this paper, we report the superfluorescent spectra and time profiles of biexcitons in CuCl QDs where a complete population inversion between the biexciton and exciton states was achieved by resonant two-photon excitation of biexcitons. A spontaneous emission at low excitation density changed to SF by increasing the excitation density. For a high excitation density, superfluorescent characteristics, i.e., narrowing of the pulse width and shortening of the delay time, were observed. Furthermore, broadening of the spectral width was observed, resulting from the enhancement of radiative rate of QD assembly. On the other hand, the SF at low temperature changed to an amplified spontaneous emission with the increase in temperature due to the increase in the dephasing rate. The critical temperature to generate the SF was approximately 75 K, which was considerably higher than that of other materials. We believed that the short radiative time of the biexciton caused ultrafast formation of coherence for the excited QDs. Thus, ultrashort pulsed emission from the QDs and high critical temperature in generating the SF can be realized. Considering the QD density, we expect achieve generation of short pulsed coherent emission of less than 1 ps. We conclude that the ultrashort radiation and high-temperature performance are expected SF characteristics of semiconductor QDs.

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Section: Introductionmentioning

confidence: 57%

Section: ■ Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 77%

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Ultrashort Radiation of Biexcitonic Superfluorescence from High-Density Assembly of Semiconductor Quantum Dots

2017

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“…More recently, time-resolved photoluminescence experiments on ensembles of CuCl nanocrystals embedded in a NaCl matrix have exhibited signs of cooperative emission, including a delayed pulse [114][115][116]. Population inversion between the biexciton and exciton states was efficiently achieved via resonant two-photon excitation of biexcitons; this strategy avoids direct excitation of the exciton state since the biexciton energy is smaller than twice the exciton energy.…”

Section: Semiconductor Quantum Dots and Nanocrystalsmentioning

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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“…In this approach, the nonlinear dynamics of each emitter and the field generated by the emitters' polarization are self-consistently computed, showing a rich phenomenology of short-and long-lived excitations and synchronized oscillations. Since the local configuration of emitters can be engineered in solid-state systems, we consider parameters typical of semiconductor quantum dot systems embedded in a solid matrix, which exhibit strong dipoles and where collective radiative effects have been experimentally observed [14][15][16][17]. However, the computational framework is sufficiently general so as enable exploration of other systems such as optical centers in solids and atomic clouds.…”

mentioning

confidence: 99%

Transient dynamics of subradiance and superradiance in open optical ensembles

Lu¹,

Shanker²,

Piermarocchi³

2022

Preprint

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We introduce a computational Maxwell-Bloch framework for investigating out of equilibrium optical emitters in open cavity-less systems. To do so, we compute the pulse-induced dynamics of each emitter from fundamental light-matter interactions and self-consistently calculate their radiative coupling, including phase inhomogeneity from propagation effects. This semiclassical framework is applied to open systems of quantum dots with different density and dipolar coupling. We observe that signatures of superradiant behavior, such as directionality and faster decay, are weak for systems with extensions comparable to λ/2. In contrast, subradiant features are robust and can produce long-term population trapping effects. This computational tool enables quantitative investigations of large optical ensembles in the time domain and could be used to design new systems with enhanced superradiant and subradiant properties.

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Biexcitonic superfluorescence from CuCl quantum dots under resonant two‐photon excitation

Cited by 9 publications

References 13 publications

Ultrashort Radiation of Biexcitonic Superfluorescence from High-Density Assembly of Semiconductor Quantum Dots

Ultrashort Radiation of Biexcitonic Superfluorescence from High-Density Assembly of Semiconductor Quantum Dots

Dicke superradiance in solids [Invited]

Transient dynamics of subradiance and superradiance in open optical ensembles

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