Dynamics of excitons in individual InAs quantum dots revealed in four-wave mixing spectroscopy

Abstract

A detailed understanding of the population and coherence dynamics in optically driven individual emitters in solids and their signatures in ultrafast nonlinear-optical signals is of prime importance for their applications in future quantum and optical technologies. In a combined experimental and theoretical study on exciton complexes in single semiconductor quantum dots we reveal a detailed picture of the dynamics employing three-beam polarization-resolved fourwave mixing (FWM) micro-spectroscopy. The oscillatory dynamics of the FWM signals in the exciton-biexciton system is governed by the fine-structure splitting and the biexciton binding energy in an excellent quantitative agreement between measurement and analytical description. The analysis of the excitation conditions exhibits a dependence of the dynamics on the specific choice of polarization configuration, pulse areas and temporal ordering of driving fields. The interplay between the transitions in the four-level exciton system leads to rich evolution of coherence and population. Using two-dimensional FWM spectroscopy we elucidate the excitonbiexciton coupling and identify neutral and charged exciton complexes in a single quantum dot. Our investigations thus clearly reveal that FWM spectroscopy is a powerful tool to characterize spectral and dynamical properties of single quantum structures.

Rabi oscillations of a quantum dot exciton coupled to acoustic phonons: coherence and population readout

“…In the limit of ultrafast laser pulse excitation, in the range of τ ≈ 100 fs, we have shown that simulations in the delta-pulse limit yield a satisfactory agreement with experiments [38,46]. In this limit, the properties of the excited phonons only depend on the final occupation of the exciton state [47].…”

“…S1(a)). A strong influence from the biexciton state would also lead to a beating for positive delays due to the biexciton binding energy [38]. Because the pulse spectrum has only little overlap with the exciton to biexciton transition, we do not resolve this beating for positive delays.…”

“…To measure FWM on individual QDs, we employ a three-beam heterodyne spectral interferometry setup optimized for the near-infrared spectral range [38] as schematically depicted in Fig. 1.…”

Charge and spin control of ultrafast electron and hole dynamics in single CdSe/ZnSe quantum dots

“…In this context and the context of the single-photon amplifier, it is important to understand the intrinsic relaxation mechanisms which can influence preparation and readout of the few-particle quantum states via ultrashort light pulses. To this end, charge-carrier dynamics in QDs based on III-V semiconductors with shallow quantum confinement has been studied both in large ensembles [18][19][20] and single specimens [7,[21][22][23][24][25][26]. These developments have culminated in demonstrations of optical writing and readout of spin states in single or coupled QDs [13][14][15][16][17]27].…”

Photon echoes from (In,Ga)As quantum dots embedded in a Tamm-plasmon microcavity

“…TFWM and two-dimensional Fourier spectroscopy were used to investigate the coherent optical response of exciton polaritons in QW-and QDbased microcavities with high quality factors (strong coupling regime) [2,18,19]. QDs were also implemented in low quality DBR-based cavities in order to increase the strength of the TFWM signal and to study the corresponding coherent optical phenomena [20][21][22]. However, studies of the nonlinear optical response under resonant excitation in TP resonators is lacking.…”