Nonequilibrium carrier dynamics in self-assembled quantum dots

Geller, M.

doi:10.1063/1.5091742

Cited by 15 publications

(10 citation statements)

References 259 publications

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“…These transitions can be used to generate single photon sources 3,4 with high photon indistinguishability, 5,6 an important prerequisite to use quantum dots as building blocks in (optical) quantum information and communication technologies. 7,8 Moreover, self-assembled QDs are still one of the best model systems to study in an artificial atom the carrier dynamics, 9,10 the spin-and angular-momentum properties 11,12 and charge carrier interactions. 13 One important effect of carrier interactions is the Auger process: An electron-hole pair recombines and instead of emitting a photon, the recombination energy is transferred to a third charge carrier, which is then energetically ejected from the QD.…”

Section: Statistics Random Telegraph Signalmentioning

confidence: 99%

Real-Time Detection of Single Auger Recombination Events in a Self-Assembled Quantum Dot

et al. 2020

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Auger recombination is a non-radiative process, where the recombination energy of an electron-hole pair is transferred to a third charge carrier. It is a common effect in colloidal quantum dots that quenches the radiative emission with an Auger recombination time below nanoseconds. In self-assembled QDs, the Auger recombination has been observed with a much longer recombination time in the order of microseconds.Here, we use two-color laser excitation on the exciton and trion transition in resonance fluorescence on a single self-assembled quantum dot to monitor in real-time every quantum event of the Auger process. Full counting statistics on the random telegraph signal give access to the cumulants and demonstrate the tunability of the Fano factor from a 1 arXiv:1911.04789v2 [cond-mat.mes-hall] 13 Nov 2019Poissonian to a sub-Poissonian distribution by Auger-mediated electron emission from the dot. Therefore, the Auger process can be used to tune optically the charge carrier occupation of the dot by the incident laser intensity; independently from the electron tunneling from the reservoir by the gate voltage. Our findings are not only highly relevant for the understanding of the Auger process, it also demonstrates the perspective of the Auger effect for controlling precisely the charge state in a quantum system by optical means.The excitonic transitions in self-assembled quantum dots (QDs) 1,2 realize perfectly a twolevel system in a solid-state environment. These transitions can be used to generate single photon sources 3,4 with high photon indistinguishability, 5,6 an important prerequisite to use quantum dots as building blocks in (optical) quantum information and communication technologies. 7,8 Moreover, self-assembled QDs are still one of the best model systems to study in an artificial atom the carrier dynamics, 9,10 the spin-and angular-momentum properties 11,12 and charge carrier interactions. 13 One important effect of carrier interactions is the Auger process: An electron-hole pair recombines and instead of emitting a photon, the recombination energy is transferred to a third charge carrier, which is then energetically ejected from the QD. 14-17 This is a common effect, mostly studied in colloidal QDs, where it quenches the radiative emission with recombination times in the order of picoseconds to nanoseconds. [18][19][20] This limits the efficiency of optical devices containing QDs like LEDs 21,22 or single photon sources. [23][24][25] In self-assembled QDs, Auger recombination was speculated to be absent, and only recently, it was directly observed in optical measurements on a single self-assembled QD coupled to a charge reservoir with recombination times in the order of microseconds. 26As a single Auger process is a quantum event, it is unpredictable and only the statistical evaluation of many processes gives access to the physical information of the recombination

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Section: Statistics Random Telegraph Signalmentioning

confidence: 99%

Real-Time Detection of Single Auger Recombination Events in a Self-Assembled Quantum Dot

et al. 2020

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“…An applied voltage between charge reservoir and gate can control the charge state of the QD. 26,35 Furthermore, the resonance of the QD can be tuned by the quantum confined Stark effect. 36 The QD is optically investigated by resonance fluorescence, where the laser background is suppressed by cross polarization.…”

Section: Sample Design and Methodsmentioning

confidence: 99%

“…This scattering process is well known from colloidal QDs [22][23][24] and has been directly observed just recently in resonance fluorescence measurements 25 with Auger recombination rates in the order of microseconds. [26][27][28][29] In this paper, we show time-resolved resonance fluorescence (RF) measurements on the trion transitions of a a) Electronic mail: hendrik.mannel@uni-due.de negatively-charged InAs QD, embedded in an electrically controllable diode structure and charged by electron tunneling from a nearby charge reservoir. An applied magnetic field B of up to 10 T in Faraday geometry (here, parallel to the growth axis) splits the trion into a lower ("red") and a higher ("blue") energy transition.…”

Section: Introductionmentioning

confidence: 99%

Auger and spin dynamics in a self-assembled quantum dot

Mannel¹,

Kerski²,

Lochner³

et al. 2021

Preprint

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The Zeeman-split spin states of a single quantum dot can be used together with its optical trion transitions to form a spin-photon interface between a stationary (the spin) and a flying (the photon) quantum bit. Besides long coherence times of the spin state itself, the limiting decoherence mechanisms of the trion states are of central importance. We investigate here in time-resolved resonance fluorescence the electron and trion dynamics in a single self-assembled quantum dot in an applied magnetic field of up to B = 10 T. The quantum dot is only weakly coupled to an electron reservoir with tunneling rates of about 1 ms −1 . Using this sample structure, we can measure, in addition to the spin-flip rate of the electron and the spin-flip Raman rate of the trion transition, the Auger recombination process, that scatters an Auger electron into the conduction band. The Auger effect destroys the radiative trion transition and leaves the quantum dot empty until an electron tunnels from the reservoir into the dot. The Auger recombination rate decreases by a factor of three from γ A = 3 µs −1 down to 1 µs −1 in an applied magnetic field of 10 T in Faraday geometry. The combination of an Auger recombination event with subsequent electron tunneling from the reservoir can flip the electron spin and thus constitutes a previously unaccounted mechanism that limits spin coherence, an important resource for quantum technologies.

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“…[25,26]. As a concrete experimental realization, we consider a quantum dot coupled to a reservoir in the form of an effectively two-dimensional electron gas (2DEG) [27][28][29][30][31].…”

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Quantum Zeno Isolation of Quantum Dots

Ahmadiniaz¹,

Geller²,

König³

et al. 2022

Preprint

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We investigate whether and how the quantum Zeno effect, i.e., the inhibition of quantum evolution by frequent measurements, can be employed to isolate a quantum dot from its surrounding electron reservoir. In contrast to the often studied case of tunneling between discrete levels, we consider the tunnelling of an electron from a continuum reservoir to a discrete level in the dot. Realizing the quantum Zeno effect in this scenario can be much harder because the measurements should be repeated before the wave packet of the hole left behind in the reservoir moves away from the vicinity of the dot. Thus, the required repetition rate could be lowered by having a flat band (with a slow group velocity) in resonance with the dot or a sufficiently small Fermi velocity or a strong external magnetic field.

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Nonequilibrium carrier dynamics in self-assembled quantum dots

Cited by 15 publications

References 259 publications

Real-Time Detection of Single Auger Recombination Events in a Self-Assembled Quantum Dot

Real-Time Detection of Single Auger Recombination Events in a Self-Assembled Quantum Dot

Auger and spin dynamics in a self-assembled quantum dot

Quantum Zeno Isolation of Quantum Dots

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