Phonon wave packet emission during state preparation of a semiconductor quantum dot using different schemes

TL;DR

This paper analyzes phonon wave packet emission during different quantum dot state preparation schemes, revealing how phonon interactions affect fidelity and guiding the design of improved methods.

Contribution

It provides a comparative analysis of phonon wave packet emission in various excitation schemes, including Rabi, adiabatic rapid passage, and swing-up, highlighting their impact on fidelity.

Findings

Phonon wave packets are emitted during Rabi and swing-up schemes, degrading fidelity.

Adiabatic rapid passage maintains high fidelity despite phonon emission.

Matching the swing-up frequency with phonon spectral density peaks increases wave packet emission.

Abstract

The carrier-phonon interaction in semiconductor quantum dots can greatly affect the optical preparation of the excited state. For resonant excitation used in the Rabi preparation scheme, the polaron is formed accompanied by the emission of a phonon wave packet, leading to a degradation of preparation fidelity. In this paper, phonon wave packets for different coherent excitation schemes are analyzed. One example is the adiabatic rapid passage scheme relying on a chirped excitation. Here, also a phonon wave packet is emitted, but the preparation fidelity can still be approximately unity. A focus is on the phonon impact on a recently proposed swing-up scheme, induced by two detuned pulses. Similar to the Rabi scheme, a degradation and a phonon wave packet emission is found, despite the detuning. If the swing-up frequency coincides with the maximum of the phonon spectral density, a series of wave packets is emitted yielding an even stronger degradation. The insight gained from our results will further help in designing an optimal preparation scheme for quantum dots.