Efficient population transfer in a quantum dot exciton under phonon-induced decoherence via shortcuts to adiabaticity

TL;DR

This work demonstrates that shortcuts to adiabaticity, implemented as transitionless driving pulses, enable fast and robust ground-to-exciton population transfer in GaAs/InGaAs quantum dots despite phonon-induced decoherence. The authors derive explicit STA control fields and validate their effectiveness using the numerically exact TEMPO method to capture non-Markovian phonon dynamics, complemented by Bloch-like equations for intuition at low temperatures. They find high transfer efficiency for temperatures below ~20 K and pulse durations up to ~10 ps, with subpicosecond pulses remaining effective at higher temperatures due to delta-like Rabi activity. The results support applications in on-demand single-photon generation and provide a framework for optimizing control in open quantum-dot systems.

Abstract

In the present study, we apply shortcut to adiabaticity pulses (time-dependent Rabi frequency and detuning) for the efficient population transfer from the ground to the exciton state in a GaAs/InGaAs quantum dot with phonon-induced dephasing. We use the time-evolving matrix product operator (TEMPO) method to propagate system in time and find that, for temperatures below $ 20 \ \text{K} $ and pulse duration up to $ 10 \ \text{ps} $, a very good transfer efficiency is obtained in general. We explain these results using a Bloch-like equation derived from a generalized Lindblad equation, which adequately describes system dynamics at lower temperatures. For higher temperatures, the transfer efficiency is significantly reduced except for subpicosecond pulses, where the shortcut Rabi frequency reduces to a delta pulse attaining a fast population inversion. The present work is expected to find application in quantum technologies which exploit quantum dots for single-photon generation on demand.

Figures (9)

• Figure 1: Time-dependent detuning $\Delta(t)$ of the applied field obtained from Eqs. (\ref{['fields']}) using Eqs. (\ref{['E']}) and (\ref{['theta']}), for various values of the pulse duration $T = 0.5, 2.4, 4.3, 6.2, 8.1, 10 \ \text{ps}$ and parameter $\Omega_0 = 0.5 \ \text{ps}^{-1}$ (a), $1 \ \text{ps}^{-1}$ (b), $1.5 \ \text{ps}^{-1}$ (c), and $2 \ \text{ps}^{-1}$ (d).
• Figure 2: Time-dependent Rabi frequency $\Omega(t)$ obtained as in Fig. 1, where note that, since there is no visible difference for different values $\Omega_0 = 0.5, 1, 1.5, 2 \ \text{ps}^{-1}$, only the case with $\Omega_0 = 0.5 \ \text{ps}^{-1}$ is shown.
• Figure 3: Population of exciton state after the application of shortcut pulses, as a function of pulse duration up to $10 \ \text{ps}$ and temperature in the range $0-100 \ \text{K}$, for different values of parameter $\Omega_0 = 0.5 \ \text{ps}^{-1}$ (a), $1 \ \text{ps}^{-1}$ (b), $1.5 \ \text{ps}^{-1}$ (c), and $2 \ \text{ps}^{-1}$ (d). The results are obtained using the TEMPO method.
• Figure 4: Same as in Fig. \ref{['fig:LHTD']} but the results are obtained using Eqs. (\ref{['bloch']}) instead of TEMPO.
• Figure 5: Final exciton population achieved with the shortcut pulses versus pulse duration, calculated with TEMPO (red curve) and Eqs. (\ref{['bloch']}) (blue curve), for temperatures $1 \ \text{K}$ (a), $10 \ \text{K}$ (b), and $50 \ \text{K}$ (c).