Year: 2022
Type: article
Abstract: An unambiguous observation of the Bose-Einstein condensation (BEC) of excitons in a photoexcited bulk semiconductor and elucidation of its inherent nature have been longstanding problems in condensed matter physics. Here, we observe the quantum phase transition and a Bose-Einstein condensate appearing in a trapped gas of 1s paraexcitons in bulk Cu2O below 400 mK, by directly visualizing the exciton cloud in real space using mid-infrared induced absorption imaging that we realized in a dilution refrigerator. Our study shows that the paraexciton condensate is undetectable by conventional luminescence spectroscopy. We find an unconventionally small condensate fraction of 0.016 with the spatial profile of the condensate well described by mean-field theory. Our discovery of this new type of BEC in the purely matter-like exciton system interacting with a cold phonon bath could pave the way for the classification of its long-range order, and for essential understanding of quantum statistical mechanics of non-equilibrium open systems.
Source: Nature Communications
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $5,890
Awards: Fundamental investigation of photoexcited electron dynamics in semiconductors using laser photoelectron spectroscopy, Realization of laser cooling of positronium atoms and test of the weak equivalence principle using an optical frequency comb, Precision measurement of quantum degenerate bulk excitons by excitonic Lyman spectroscopy, Research on formation of quantum ordered states in ultra cold electron-hole system by spectroscopy of electron states under extreme environments, G5921803673, Direct detection of exciton Bose-Einstein Condensation and research on spatio-temporal dynamics, G997380163
OpenAlex ID: W4295679042