NCTS (South)


DATE2019-12-16

TIME12:10

PLACER49223, Second Physics Building , NCKU

FIELDQuantum Information Science

SPEAKER Prof. Shiue-Yuan Shiau(蕭學遠) - 國家理論科學研究中心

TITLE Composite boson nature of atomicdimers and semiconductor excitons in the interference pattern of colliding condensates

ABSTRACTAll particles consisting of an even number of fermions are boson-like, which bears a strong consequence: they must undergo Bose-Einstein condensation. In this seminar, I will show thatin contrast to elementary bosons, the interference pattern of two colliding BEC made of fermionic-atom dimers must have additional high-frequency oscillatory modes. These higher frequency modes are a striking evidence of the dimer composite nature. I will also discuss the conditions to see them experimentally using optical lattices. The composite nature of semiconductor excitons, on the other hand, has a more dramatic consequence. Because semiconductor conduction electrons and valence holes carry spins, excitons can be bright or dark, i.e., coupled or not coupled to photons.I will show that it is exactly due to the composite nature of excitons that we finally have a way to probe the quantum coherence of dark exciton condensates, previously thought to be optically inaccessible. SY Siau, A. Chenu, M. Combescot, New J. Phys. 21, 043041(2019) SY Shiau, M. Combescot, Phys. Rev. Lett. 123, 097401(2019)