Impact of Bright-Dark Exciton Thermal Population Mixing on the Brightness of CsPbBr Nanocrystals.

Understanding the interplay between bright and dark exciton states is crucial for deciphering the luminescence properties of low-dimensional materials. The origin of the outstanding brightness of lead halide perovskites remains elusive. Here, we analyze temperature-dependent time-resolved photoluminescence to investigate the population mixing between bright and dark exciton sublevels in individual CsPbBr nanocrystals in the intermediate confinement regime.

Spectral Fingerprint of Quantum Confinement in Single CsPbBr Nanocrystals.

Lead halide perovskite nanocrystals are promising materials for classical and quantum light emission. To understand these outstanding properties, a thorough analysis of the band-edge exciton emission is needed, which is not reachable in ensemble and room-temperature studies because of broadening effects. Here, we report on a cryogenic-temperature study of the photoluminescence of single CsPbBr nanocrystals in the intermediate quantum confinement regime.

Unveiling the Enhancement of Spontaneous Emission at Exceptional Points.

Exceptional points (EPs), singularities of non-Hermitian physics where complex spectral resonances degenerate, are one of the most exotic features of nonequilibrium open systems with unique properties. For instance, the emission rate of quantum emitters placed near resonators with EPs is enhanced (compared to the free-space emission rate) by a factor that scales quadratically with the resonance quality factor. Here, we verify the theory of spontaneous emission at EPs by measuring photoluminescence from photonic-crystal slabs that are embedded with a high-quantum-yield active material.

Intermittent Theta-Burst Stimulation Transcranial Magnetic Stimulation Increases GABA in the Medial Prefrontal Cortex: A Preliminary Sham-Controlled Magnetic Resonance Spectroscopy Study in Acute Bipolar Depression.

Magnetic resonance spectroscopy (MRS) has been used to identify gamma-aminobutyric acid (GABA) alterations in mood disorders, particularly in the medial prefrontal cortex (mPFC) where decreased concentrations have been associated with anhedonia. In major depressive disorder (MDD), prior work suggests that repetitive transcranial magnetic stimulation (rTMS) increases mPFC GABA concentrations proportional to antidepressant response. To our knowledge, this has not been examined in acute bipolar depression.

Ultralow Threshold Polariton Condensate in a Monolayer Semiconductor Microcavity at Room Temperature.

Exciton-polaritons, hybrid light-matter bosonic quasiparticles, can condense into a single quantum state, i.e., forming a polariton Bose-Einstein condensate (BEC), which represents a crucial step for the development of nanophotonic technology.