Decoherence Dynamics of Localized States in a Single GaAs/AlGaAs Quantum Ring

Abstract

Interferometric correlation spectroscopy is performed to investigate the decoherence dynamics of localized excited states in a single GaAs/AlGaAs quantum ring. For increasing temperature and excitation, we observe that the decay of interferometric envelope and the Fourier‐transformed spectrum remain exponential and Lorentzian, respectively. The linewidth broadening for temperature and excitation intensity can be attributed to enhanced acoustic phonon scattering and Auger scattering in the fast modulation limit through the barrier traps, where carriers are captured and escape randomly. Additionally, we suggest an internal scattering between the different vertical confinement states for the significantly short coherence time (<25 ps) compared to that observed in quantum dots.

Elliptical Polarization of Localized States in an Anisotropic Single GaAs Quantum Ring

“…However, the level spacing between the levels in QR is fine with sub-meV, and this causes various inelastic scattering. Recently, it has been found that the coherence time of a single QRs is under 30 ps [ 21 ].…”

Modeling Quantum Beats by Degenerate Four‐Wave Mixing Spectroscopy in a Single GaAs/AlGaAs Quantum Ring

“…Regarding that the AB effect emerges in limited conditions of quantum coherence, this technique is of an importance for investigating the quantum coherence of an electron–hole pair rotating in a QR. So far coherent spectroscopy of QRs was barely studied …”

“…However, recent work suggested that an internal scattering between the different vertical confinement states also contributes as an additional decoherence scattering. Regarding ≈25 ps of coherence time in localized excited states of a single GaAs/AlGaAs QR, we assumed T 2 = 10 ps for a wavefunction extended around the ring circumference. Consequently, while | P (3) ( t , τ )| 2 ∼ exp[−2 τ / T 2 ] decays for increasing τ (Figure (b)), the seven different states ( l = 0–6) contribute to oscillations in | P (3) ( t , τ )| 2 .…”

“…So far coherent spectroscopy of QRs was barely studied. [9,10] In this work, we have proposed that a degenerate four-wave mixing (DFWM) spectroscopy can be utilized to investigate the fine levels of a QR. For DFWM signals, we have calculated transient optical nonlinearities of the fine levels in a GaAs/ AlGaAs QR by utilizing the semiconductor Bloch equation.…”