Mechanism for Macroscopic Quantum Coherence in Perovskite Superfluorescence*

As the demand for quantum approaches in computing, communication, and cryptology is increasing, the need for discovering new “quantum materials” is unprecedented. While the required quantum properties are known for most applications, the designer's rules for producing these materials are unclear, and quantum materials functioning at room temperature are almost non-existent. One of the significant challenges is the short lifetime of quantum coherent states at practically relevant temperatures.  Since the quantum phase is highly fragile due to thermal scattering events, we have the following questions: Are thermal processes a fundamental roadblock for designing quantum materials with extended coherence? Is there a way to protect quantum coherence despite thermal scattering? We recently observed room-temperature superfluorescence in lead-halide perovskites. Superfluorescence (SF) is a collective emission due to the macroscopic quantum state of optically excited dipoles. In the solid state, SF observation is generally limited to low temperatures due to the fast thermal dephasing of electronic excitations. All early observations of SF in the solid state are in two-level systems (discrete transition). Therefore, the observation of SF in hybrid perovskites with extended electronic states (bands) is quite surprising. This observation points to a mechanism protecting a quantum system's quantum phase from thermal disturbances in lead-halide perovskites. In this talk, I will present the Quantum Analog of Vibration Isolation (QAVI) model and its signatures protecting the quantum phase transition of incoherent dipoles into a macroscopically coherent superradiant state in perovskites.