"Gray" BCS condensate of excitons and internal Josephson effect

Abstract

It has been recently suggested that the Bose-Einstein condensate formed by excitons in the dilute limit must be dark, i.e., not coupled to photons. Here, we show that, under a density increase, the dark exciton condensate must acquire a bright component due to carrier exchange in which dark excitons turn bright. This however requires a density larger than a threshold which seems to fall in the forbidden region of the phase separation between a dilute exciton gas and a dense electron-hole plasma. The BCS-like condensation which is likely to take place on the dense side, must then have a dark and a bright component - which makes it "gray". It should be possible to induce an internal Josephson effect between these two coherent components, with oscillations of the photoluminescence as a strong proof of the existence for this "gray" BCS-like exciton condensate.

4 pages, typo corrected

References in corpus (4)

• Theory of ultracold Fermi gases
• Analysis of the exciton-exciton interaction in semiconductor quantum wells
• BEC-BCS Crossover and the Liquid-Gas Phase Transition in Hot and Dense Nuclear Matter
• Polariton-polariton scattering: exact results through a novel approach

Cited by in corpus (20)

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• Evidence for a Bose-Einstein condensate of excitons
• Quantized Vortices and Four-Component Superfluidity of Semiconductor Excitons
• Experimental Study of the Exciton Gas Liquid Transition in Coupled Quantum Wells
• Effects of fermion exchanges on the polarization of exciton condensates
• Leaky exciton condensates in transition metal dichalcogenide moiré bilayers
• Roton-maxon spectrum and instability for weakly interacting dipolar excitons in a semiconductor layer
• Collective interlayer pairing and pair superfluidity in vertically stacked layers of dipolar excitons
• Defect-Driven Superfluid Crossover for Two-Dimensional Dipolar Excitons Trapped at Thermodynamic Equilibrium
• Confocal shift interferometry of coherent emission from trapped dipolar excitons
• Vortices in spinor cold exciton condensates with spin-orbit interaction
• Optical signatures of a fully dark exciton condensate
• Optical signature of quantum coherence in fully dark exciton condensates
• The Role of Spin-Flip Collisions in a Dark Exciton Condensate
• Condensation to a strongly correlated dark fluid of two dimensional dipolar excitons
• Scattering amplitudes for dark and bright excitons
• Phonon-induced modification of polaritonic Rabi oscillations in the presence of the dark excitonic condensate
• Symmetry induced pairing in dark excitonic condensate at finite temperature
• Partition function of N composite bosons
• Giant Hyperfine Interaction between a Dark Exciton Condensate and Nuclei