Correlation and dephasing effects on the non-radiative coherence between bright excitons in an InAs QD ensemble measured with 2D spectroscopy

Singh, Rohan; Li, Hebin; Акимов, И. А.; Bayer, М.; Reuter, D.; Wieck, A. D.; Cundiff, Steven T.

doi:10.1016/j.ssc.2013.03.025

Cited by 30 publications

(25 citation statements)

References 34 publications

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“…We note that the factor of one-half in front of T 1 for the expression for interband optical decoherence is absent in the expression above for valley coherence, since recombination from either valley contributes to valley decoherence. With the assumption that scattering events in the K and K ′ valleys are uncorrelated, we can express the valley coherence time as

{false(τ_{v} false)}^{- 1} = {false(T_{1} false)}^{- 1} + 2 {false(T_{2}^{*} false)}^{- 1}

[33,34], i.e. trion valley coherence is governed by recombination and pure optical dephasing processes.…”

Section: Resultsmentioning

confidence: 99%

Trion valley coherence in monolayer semiconductors

Hao

et al. 2017

2D Mater.

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The emerging field of valleytronics aims to exploit the valley pseudospin of electrons residing near Bloch band extrema as an information carrier. Recent experiments demonstrating optical generation and manipulation of exciton valley coherence (the superposition of electron-hole pairs at opposite valleys) in monolayer transition metal dichalcogenides (TMDs) provide a critical step towards control of this quantum degree of freedom. The charged exciton (trion) in TMDs is an intriguing alternative to the neutral exciton for control of valley pseudospin because of its long spontaneous recombination lifetime, its robust valley polarization, and its coupling to residual electronic spin. Trion valley coherence has however been unexplored due to experimental challenges in accessing it spectroscopically. In this work, we employ ultrafast two-dimensional coherent spectroscopy to resonantly generate and detect trion valley coherence in monolayer MoSe2 demonstrating that it persists for a few-hundred femtoseconds. We conclude that the underlying mechanisms limiting trion valley coherence are fundamentally different from those applicable to exciton valley coherence.

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{false(τ_{v} false)}^{- 1} = {false(T_{1} false)}^{- 1} + 2 {false(T_{2}^{*} false)}^{- 1}

[33,34], i.e. trion valley coherence is governed by recombination and pure optical dephasing processes.…”

Section: Resultsmentioning

confidence: 99%

Trion valley coherence in monolayer semiconductors

Hao

et al. 2017

2D Mater.

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“…However, singledot experiments, which require long signal integration times, still suffer from spectral diffusion effects that mask the intrinsic recombination dynamics [4,13,14]. These limitations can be avoided by investigating QD ensembles using spin noise spectroscopy [15,16] or nonlinear optical spectroscopy techniques, such as spectral hole burning [17][18][19], four-wave mixing [20], or coherent multidimensional spectroscopy [21,22]. An ultralong coherence time up to ∼1.5 ns, corresponding to a sub-μeV dephasing rate, has been measured for the positively charged exciton in InAs QDs at cryogenic temperature [23].…”

Section: Introductionmentioning

confidence: 99%

Homogeneous linewidth narrowing of the charged exciton via nuclear spin screening in an InAs/GaAs quantum dot ensemble

et al. 2014

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In semiconductor quantum dots, the electron hyperfine interaction with the nuclear spin bath is the leading source of spin decoherence at cryogenic temperature. Using high-resolution two-color differential transmission spectroscopy, we demonstrate that such electron-nuclear coupling also imposes a lower limit for the positively charged exciton dephasing rate, γ , in an ensemble of InAs/GaAs quantum dots. We find that γ is sensitive to the energetic overlap of the charged exciton spin states, which can be controlled through the application of an external magnetic field in the Faraday configuration. At zero applied field, electron-nuclear coupling induces additional dephasing beyond the radiative limit and γ = 230 MHz (0.95 μeV). Screening of the hyperfine interaction is achieved for an external field of ≈1 T, resulting in γ = 172 MHz (0.71 μeV) limited only by spontaneous recombination along the dipole-allowed transition. These results are reproduced with a simple and intuitive model that captures the essential features of the electron hyperfine interaction and its influence on γ .

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“…In a one-quantum (zero-quantum) 2D experiment, interferograms are recorded while stepping the delay τ (T ). The signal is Fourier transformed with respect to this delay to produce a one-quantum (zero-quantum) 2D spectrum that correlates the excitation (mixing) and emission energies [19][20][21][22]. We can also obtain information on twoquantum coherences using a pulse sequence with the con- jugated pulse A incident on the sample last, providing a 2D spectrum that correlates emission and two-quantum excitation energies [23][24][25][26].…”

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confidence: 99%

Coherent Excitonic Coupling in an Asymmetric Double InGaAs Quantum Well Arises from Many-Body Effects

et al. 2014

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We study an asymmetric double InGaAs quantum well using optical two-dimensional coherent spectroscopy. The collection of zero-quantum, one-quantum and two-quantum two-dimensional spectra provides a unique and comprehensive picture of the double well coherent optical response. Coherent and incoherent contributions to the coupling between the two quantum well excitons are clearly separated. An excellent agreement with density matrix calculations reveals that coherent inter-well coupling originates from many-body interactions.Coupled quantum wells (QWs) are one of the most fundamental topics of quantum mechanics. They can be realized in epitaxially-grown semiconductor materials, where the coupling can be exploited in optoelectronic devices such as quantum cascade lasers [1]. Furthermore, since QW and barrier sizes can be tailored, coupled semiconductor QWs can serve as a model for other systems. For example, the absence of vibrational coupling in semiconductor QWs allows isolation of electronic coupling; this distinctive feature may help understanding extremely efficient energy transfer in light harvesting complexes, where the roles played by electronic and vibrational coupling are under debate [2][3][4][5]. Semiconductor double QWs (DQWs) have attracted theoretical and experimental attention for more than twenty years. The roles of resonant transfer and wavefunction hybridization [6][7][8], phonon-assisted tunneling [9,10], dipole-dipole coupling [11], percolation of carriers through imperfect barriers [12], and thermally activated charge transfer [13] have been studied and discussed, as well as the formation of indirect excitons [14,15]. However, the role played by many-body effects-which have been shown to dominate the coherent response of semiconductor excitons [16,17]-in the coupling mechanism has been neglected so far.We use optical two-dimensional coherent spectroscopy (2DCS) to characterize coupling between the QW excitons, which are electron-hole pairs bound together by their Coulomb attraction. 2DCS is an extension of transient four-wave-mixing (FWM) spectroscopy, with the addition of interferometric stabilization of inter-pulse delays and measurement of the signal field. It is an ideal technique to study coupling between resonances, since unfolding one-dimensional spectra onto a second dimension distinguishes quantum beats from polarization interferences [18]. Additionally, 2DCS has been demonstrated as a powerful tool for revealing many-body effects in semiconductor nanostructures [16,17]. Several types of 2D spectra-isolating zero-, one-, and two-quantum coherences-have been shown in previous work to reveal information that one-dimensional techniques cannot access [19][20][21][22][23][24][25][26], but these different types of spectra have never been recorded and analyzed together for a single system so far. Previously, multidimensional spectroscopy showed electronic coherences between excitonic transitions of a GaAs/AlGaAs DQW [27][28][29]. However, the presence of heavy and light holes in each GaAs/Al...

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Correlation and dephasing effects on the non-radiative coherence between bright excitons in an InAs QD ensemble measured with 2D spectroscopy

Cited by 30 publications

References 34 publications

Trion valley coherence in monolayer semiconductors

Trion valley coherence in monolayer semiconductors

Homogeneous linewidth narrowing of the charged exciton via nuclear spin screening in an InAs/GaAs quantum dot ensemble

Coherent Excitonic Coupling in an Asymmetric Double InGaAs Quantum Well Arises from Many-Body Effects

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