Perturbation-driven echo-like superfluorescence in perovskite superlattices

The collective response of macroscopic quantum states under perturbation is widely used to study quantum correlations and cooperative properties,such as defect-induced quantum vortices in Bose–Einstein condensates and the non-destructive scattering of impurities in superfluids.Superfluorescence(SF),as a collective effect rooted in dipole–dipole cooperation through virtual photon exchange,leads to the macroscopic dipole moment(MDM)in high-density dipole ensembles.However,the perturbation response of the MDM in SF systems remains unknown.Echo-like behavior is observed in a cooperative exciton ensemble under a controllable perturbation,corresponding to an initial collapse followed by a revival of the MDM.Such a dynamic response could refer to a phase transition between the macroscopic coherence regime and the incoherent classical state on a time scale of 10 ps.The echo-like behavior is absent above 100 K due to the instability of MDM in a strongly dephased exciton ensemble.Experimentally,the MDM response to perturbations is shown to be controlled by the amplitude and injection time of the perturbations.

Ultrastable low-cost colloidal quantum dot microlasers of operative temperature up to 450 K

Quantum dot microlasers,as multifunaional optical source components,are of great importance for full-color highpixel display,miniaturized coherent lighting,and on-chip integrated photonic and electronic circuits.Since the first synthesis of colloidal quantum dots(CQD)in the 1990s,motivation to realize high-performance low-cost CQD micro-/nanolasers has been a driving force for more than three decades.However,the low packing density,inefficient coupling of CQDs with optical cavities,and the poor thermal stability of miniaturized complex systems make it challenging to achieve practical CQD microVnanolasers,especially to combine the continuous working ability at high temperatures and the low-cost potential with mass-produced synthesis technologies.Herein,we developed closepacked CQD-assembled microspheres and embedded them in a silica matrix through the rapid self-aggregation and solidification of CdSe/ZnS CQD.This technology addresses the core issues of photoluminescence(PL)quenching effect and low optical gain in traditional CQD laser research.High-efficiency low-threshold CQD microlasers are demonstrated together with long-playing(40 min)working stability even at 450 K under pulsed laser excitation,which is the highest operational temperature for CQD lasers.Moreover,single-mode CQD microlasers are obtained with tunable wavelengths across the entire visible spectral range.The chemosynthesis process supports the mass-produced potential of high-density integrated CQD microlasers,promoting CQD-based low-cost high-temperature microdevices.