Suppression of decoherence tied to electron–phonon coupling in telecom-compatible quantum dots: low-threshold reappearance regime for quantum state inversion

Abstract

We demonstrate suppression of dephasing tied to deformation potential coupling of confined electrons to longitudinal acoustic (LA) phonons in optical control experiments on large semiconductor quantum dots (QDs) with emission compatible with the low-dispersion telecommunications band at 1.3 µm. By exploiting the sensitivity of the electron–phonon spectral density to the size and shape of the QD, we demonstrate a fourfold reduction in the threshold pulse area required to enter the decoupled regime for exciton inversion using adiabatic rapid passage (ARP). Our calculations of the quantum state dynamics indicate that the symmetry of the QD wave function provides an additional means to engineer the electron–phonon interaction. Our findings will support the development of solid-state quantum emitters in future distributed quantum networks using semiconductor QDs.

Spectrally-modified frequency-swept pulses for optically-driven quantum light sources

“…Fig. 1(a For the unfiltered pulse, a transition from the Rabi rotation regime to the adiabatic regime is observed as φ is increased, consistent with previous work [10,[66][67][68][69][70][71][72][73].…”

“…For the unfiltered pulse with zero chirp, a damped Rabi rotation is observed. For excitation by the chirped, unfiltered pulse the PL intensity saturates at a constant value for pulse areas above the threshold for ARP, as observed in prior experiments on similar QDs [10,[66][67][68][69][70][71][72][73]. For the chirped spectral hole pulse, the exciton inversion also exhibits a saturation behaviour.…”

“…Furthermore, the choice of positive chirp in the laser pulses used to drive the emitter leads to inversion via the lower-energy dressed state, which may be used to suppress phonon-induced dephasing processes at low temperature, in contrast to other driving schemes [67]. Robust inversion has been demonstrated using ARP in solid-state emitters based on excitons in semiconductor QDs in recent years [66][67][68][69][70][71][72][73], including the driving of a triggered single photon source [10].…”

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

“…Figure 2(d)], which only reaches a values of 0.358 after the pulse. The asymmetry of the phonons regarding the sign of the chirp has been confirmed several times in experiments [7,44,45,[71][72][73].…”

Phonon Wave Packet Emission during State Preparation of a Semiconductor Quantum Dot using Different Schemes

“…The asymmetry of the phonons regarding the sign of the chirp has been confirmed several times in experiments. [7,44,45,[71][72][73] For both the Rabi and ARP scheme, the influence on the state preparation can be estimated via the dressed states. The dressed states are the eigenstates of the coupled dot-light system with the energies E AE .…”