Exciton-polaritons are composite quasiparticles resulting from strong interactions between exciton states in semiconductor quantum wells and photon modes in microcavities. They inherit an extremely small effective mass from their photonic components, and a high degree of nonlinearity from their excitonic part. Using an all-optical trap to generate a repulsive reservoir of excitons, our group has demonstrated that the formation of a quasi-equilibrium Bose-Einstein condensate is possible. Our current work is focused on the dynamic modulation and control of polariton condensates using light at visible and THz frequencies.


Overview of the excitonics subgroup

Overview of the research. (a) Schematics of the high quality GaAs microcavity used to generate long-lifetime exciton-polaritons. Twelve GaAs quantum wells are positioned at the antinodes of a 3λ/2 cavity formed by a set of two distributed Bragg reflectors (DBRs). (b) Excitons and photons strongly couple to generate new quasiparticles, the exciton-polaritons. (Inset) The experimental dispersion relation can be measured through angle-resolved photoluminescence spectroscopy. (c) Above a critical threshold, exciton-polaritons form a Bose-Einstein condensate, which is a macroscopically occupied quantum state.


Research updates:

  • "Effect of optically induced potential on the energy of trapped exciton polaritons below the condensation threshold," M. Pieczarka, M. Boozarjmehr, E. Estrecho, Y. Yoon, M. Steger, K. West, L. N. Pfeiffer, K. A. Nelson, D. W. Snoke, A. G. Truscott, and E. A. Ostrovskaya, Phys. Rev. B 100, 085301 (2019) [url]
  • "Stable switching among high-order modes in polariton condensates," Y. Sun*, Y. Yoon*, S. Khan, L. Ge, M. Steger, L. N. Pfeiffer, K. West, H. E. Türeci, D. W. Snoke, and K. A. Nelson, Phys. Rev. B 97, 045303 (2018) [url]
  • "Direct measurement of polariton–polariton interaction strength," Y. Sun, Y. Yoon, M. Steger, G. Liu, L. N. Pfeiffer, K. West, D. W. Snoke, and K. A. Nelson, Nat. Phys. 13, 870-875 (2017) [url]
  • "Bose-Einstein condensation of long-lifetime polaritons in thermal equilibrium," Y. Sun, P. Wen, Y. Yoon, G. Liu, M. Steger, L. N. Pfeiffer, K. West, D. W. Snoke, and K. A. Nelson, Phys. Rev. Lett. 118, 016602 (2017) [url]