Femtosecond Transfer and Manipulation of Persistent Hot-Trion Coherence in a Single CdSe/ZnSe Quantum Dot

TL;DR

This study demonstrates ultrafast transfer and control of hot trion coherence in a single CdSe/ZnSe quantum dot, revealing quantum beats at 133 GHz and coherence storage for 85 ps, with potential for quantum information applications.

Contribution

It presents the first detailed analysis of femtosecond transfer and manipulation of hot trion coherence in a single quantum dot, combining experimental and analytical approaches.

Findings

Quantum beats observed at 133 GHz in hot trion states.

Trionic coherence persists for 85 ps despite rapid hole relaxation.

Full control over quantum beat amplitude and phase via pump-probe polarization.

Abstract

Ultrafast transmission changes around the fundamental trion resonance are studied after exciting a p-shell exciton in a negatively charged II-VI quantum dot. The biexcitonic induced absorption reveals quantum beats between hot trion states at 133 GHz. While interband dephasing is dominated by relaxation of the P-shell hole within 390 fs, trionic coherence remains stored in the spin system for 85 ps due to Pauli blocking of the triplet electron. The complex spectro-temporal evolution of transmission is explained analytically by solving the Maxwell-Liouville equations. Pump and probe polarizations provide full control over amplitude and phase of the quantum beats.