Phonon-assisted robust and deterministic two-photon biexciton preparation in a quantum dot

TL;DR

This paper presents a phonon-assisted method for deterministic two-photon biexciton preparation in quantum dots, achieving high fidelity and stable photon coherence, offering a robust alternative to traditional Rabi oscillation protocols.

Contribution

It introduces a novel phonon-assisted excitation scheme that improves robustness and fidelity in biexciton state preparation in quantum dots.

Findings

Achieves up to 98% fidelity in biexciton preparation.

Demonstrates stable photon coherence comparable to resonant schemes.

Provides a flexible method suitable for complex solid-state quantum systems.

Abstract

We investigate both experimentally and theoretically a simple yet more robust and flexible alternative to Rabi oscillation-type biexciton preparation protocols traditionally used for semiconductor quantum dots. The quantum dot is excited by a strong laser pulse positively detuned from the two-photon resonance yielding an on demand initialization of the biexciton state by making use of the phonon-induced thermalization of the photon dressed states. It is shown that for excitation pulses in the picosecond range, a stable and high fidelity of up to $f_{XX}=0.98\pm 0.01$ is reached. Notably, the generated photons show similar coherence properties as measured in the resonant two-photon scheme. This protocol is a powerful tool for the control of complex solid state systems combining radiative cascades, entanglement and resonant cavity modes.