Programme

P.13 -- Posters, VCTP-51

Date: Tuesday, 4 August 2026

Time: 09:30 - 10:30

Spectral signatures of the BCS–BEC crossover in mass-imbalanced Semimetal/Semiconductor Microcavities

Thi-Hau Nguyen1,2, Minh-Tien Tran 3 and Van-Nham Phan4

1Hanoi University of Mining and Geology, 18 Pho Vien, Dong Ngac, Hanoi, Vietnam; 2Graduate University of Science and Technology, Vietnam Academy of Science and Technology,18 Hoang Quoc Viet, Hanoi, Vietnam; 3Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Hanoi, Vietnam; 4Institute of Research and Development, Duy Tan University, 3 Quang Trung, Danang, Vietnam.

The spectral signatures of the Bardeen-Cooper-Schrieffer (BCS) - Bose-Einstein condensation (BEC) crossover in mass-imbalanced semiconductor and semimetal microcavities are investigated. In the framework of the unrestricted HartreeFock approximation, a two-band electron-hole model involving photon mode is analyzed by treating Coulomb attraction and light-matter coupling on equal footing. The single-particle spectral functions and the luminescence properties are then examined. In the semiconducting regime, a positive band gap stabilizes tightly bound excitons and yields predominantly BEC-type excitoniclike polaritonic condensates at low density, while increasing excitation density and reducing mass imbalance drives a continuous crossover toward BCS-type pairing with intermediate and photoniclike polaritonic character. In contrast, the semimetallic regime favors itinerant electron-hole pairing, with BCS-type condensates dominating and BEC excitoniclike coherence emerging only at sufficiently strong Coulomb interaction and large mass imbalance situations. The evolution of the single-particle and luminescence spectra provides clear spectroscopic signatures of these crossover phenomena, offering a unified framework for understanding and controlling polaritonic condensates in microcavity systems.

Presenter: Nguyen Thi Hau