Time-Reversed Superfluorescence in a Polaronic Quantum Material

TL;DR

This paper demonstrates a time-reversed superfluorescence process in quantum materials, where transient polaron fields induce synchronized dipole oscillations, enabling room-temperature collective optical states.

Contribution

It introduces the concept of time-reversed superfluorescence in quantum materials and shows how polaron-mediated phase-locking can produce coherent optical states at room temperature.

Findings

Delayed cooperative absorption observed in halide perovskite quantum dots.

Coherence fidelity approaches unity at 300 K.

Microscopic model confirms polaron role in synchronization.

Abstract

Superfluorescence, the cooperative burst of spontaneous emission from an ensemble of dipoles, arises when microscopic oscillators spontaneously synchronize their phases. Here we show that this process can be reversed in time within quantum materials. Coherent multidimensional spectroscopy of halide perovskite quantum dots reveals a delayed cooperative absorption burst, the mirror image of superfluorescent emission, driven by transient polaron fields that phase-lock unit-cell dipoles within 100 fs. The effect scales systematically with quantum-dot size and halide composition, reaching near-unity coherence fidelity even at 300 K. A microscopic exciton-polaron model reproduces the buildup and decay of the coherent state, identifying lattice polarons as the mediators of synchronization. These results demonstrate that many-body temporal coherence can self-organize and persist at room temperature, opening routes toward engineered collective optical states and superabsorbing quantum devices.