Deterministic generation of a quantum-dot-confined triexciton and its radiative decay via three-photon cascade

Schmidgall, E. R.; Schwartz, I.; Gantz, Liron; Cogan, Dan; Raindel, Shachar; Gershoni, D.

doi:10.1103/physrevb.90.241411

Cited by 21 publications

(29 citation statements)

References 41 publications

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“…Since all the correlation measurements were performed together, as the system automatically changed the polarization projections every minute, all the curves are automatically normalized and no attempt was made to fit their relative intensities. The overall coincidence accumulation rate of about 10 −6 coincidences per pulse was also in agreement with the known light harvesting efficiency of our experimental setup [26]. The solid black lines represent the calculations using Eq.…”

Section: Resultssupporting

confidence: 87%

On-demand source of maximally entangled photon pairs using the biexciton-exciton radiative cascade

et al. 2017

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We perform full time resolved tomographic measurements of the polarization state of pairs of photons emitted during the radiative cascade of the confined biexciton in a semiconductor quantum dot. The biexciton was deterministically initiated using a π-area pulse into the biexciton two-photon absorption resonance. Our measurements demonstrate that the polarization states of the emitted photon pair are maximally entangled. We show that the measured degree of entanglement depends solely on the temporal resolution by which the time difference between the emissions of the photon pair is determined. A route for fabricating an on demand source of maximally polarization entangled photon pairs is thereby provided.The ability to generate entangled photons on-demand is crucial for many future applications in quantum information processing. Devices based on the biexcitonexciton radiative cascade in single semiconductor quantum dot are considered to be one of the best candidates for these applications [1][2][3]. The ability to deterministically excite the biexciton using its two-photon absorption resonance [4,5] makes this avenue even more promising. A remaining challenge, however, is the excitonic fine structure, which splits the two exciton eigenstates thus providing spectral "which-path" information on the radiative cascade and preventing the pairs of emitted photons from being polarization entangled [2]. Various strategies were tried in an attempt to reduce the influence of the fine structure splitting. Spectral [2] and temporal filtering [2,6], which introduce non desired, nondeterministic post selection. Enhancement of the radiative rate using the Purcell effect [3], thereby reducing, but not limiting the effect of exciton precession. Attempts to reduce the fine-structure splitting using heat treatment [7] or growth along the [111] crystalographic direction [8] were reported as well as applications of external stress [9], electric [10] and magnetic fields tuning [11,12]. These efforts, usually result in unwanted loss of emission quantum efficiency [10], and increase in the exciton spin decoherence [6].We present here a novel study of a single semiconductor quantum dot, optically depleted [13] and then resonantly excited on-demand by a π-area pulse to the biexciton two photon absorption resonance [5]. The resulting pairs of biexciton and exciton photons are detected by two superconducting detectors synchronized to the exciting laser pulse. By performing synchronized time resolved polarization tomography of the two emitted photons, we unambigously show that the photons remain maximally polarization entangled during the whole radiative decay, and that the measured degree of entanglement does not depend on the QD source, but rather depends on the temporal resolution by which the time difference between the two photon emissions can be determined. Since during the radiative decay the exciton does not lose coherence, there is no need to eliminate the excitonic fine structure splitting. A relatively simple arrangement [14,15] ...

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Section: Resultssupporting

confidence: 87%

On-demand source of maximally entangled photon pairs using the biexciton-exciton radiative cascade

et al. 2017

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“…Resonances indicated (i) and (iv) initiate from the BE, while resonances indicated (ii) and (iii) initiate from the DE. These optical transitions, which were previously discussed, 25,27 are schematically presented in Figure 2(c). Figure 2 clearly demonstrates that while the resonances (i) and (iv), which initiate from the BE, contribute mainly to BE emission, resonances (ii) and (iii), which initiate from DE (solid lines), contribute almost equally to the XX 0 T63 emission and to the XX 0 emission.…”

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confidence: 72%

“…These levels have been the subject of several previous studies which provide a comprehensive understanding of their spectrum, spin wavefunctions of carriers in these levels, and their dynamics. [23][24][25][26][27] Particularly relevant to this study are the nine states in which both the electrons and the heavy holes form spin-triplet configurations. [25][26][27] Such states will be indicated in this paper by the notation T e m (T h m ) representing an electron spin triplet (hole spin triplet) of projection m on the QD growth direction.…”

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confidence: 99%

“…25 There are, however, efficient spin flip and spin flip-flop mechanisms that permit this relaxation. 24,27,30 In these processes, an electron or an electron and a hole flip their spins due to the enhanced effect of the electron-hole exchange interaction in the presence of a near resonant electronlongitudinal optic (LO) phonon Fr€ ohlich interaction. 30 The process of optical depletion is schematically described in Figure 1, where Figure 1(a) describes a single DE in its ground state in the QD.…”

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All-optical depletion of dark excitons from a semiconductor quantum dot

Schmidgall

Schwartz

Cogan

et al. 2015

Applied Physics Letters

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“…1(a), we present the four possible spin configurations of the ground state triexciton. 37 Its unpaired, higher-energy electron and hole can be either in a mutual spin-parallel ("dark like") or a spin anti-parallel ("bright like" ) configuration ( Fig. 1a).…”

Section: States and Transitionsmentioning

confidence: 99%

Selection rules for nonradiative carrier relaxation processes in semiconductor quantum dots

et al. 2016

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Time resolved intensity cross-correlation measurements of radiative cascades are used for studying non-radiative relaxation processes of excited carriers confined in semiconductor quantum dots. We spectrally identify indirect radiative cascades which include intermediate phonon assisted relaxations. The energy of the first photon reveals the multicarrier configuration prior to the non-radiative relaxation, while the energy of the second photon reveals the configuration after the relaxation. The intensity cross correlation measurements thus provide quantitative measures of the non-radiative processes and their selection rules. We construct a model which accurately describes the experimental observations in terms of the electron-phonon and electron-hole exchange interactions. Our measurements and model provide a new tool for engineering relaxation processes in semiconductor nanostructures.

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Deterministic generation of a quantum-dot-confined triexciton and its radiative decay via three-photon cascade

Cited by 21 publications

References 41 publications

On-demand source of maximally entangled photon pairs using the biexciton-exciton radiative cascade

On-demand source of maximally entangled photon pairs using the biexciton-exciton radiative cascade

All-optical depletion of dark excitons from a semiconductor quantum dot

Selection rules for nonradiative carrier relaxation processes in semiconductor quantum dots

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