Phys.org May 14, 2024
Periodic temporal modulation of Hamiltonians can induce geometrical and topological phenomena in the dynamics of quantum states. Using the interference between two lasers an international team of researchers (Japan, USA – industry, Singapore, Australia, Germany) demonstrated an off-resonant optical lattice for a polariton condensate with controllable potential depths and nearest-neighbour coupling strength. Temporal modulation was introduced via a gigahertz frequency detuning between pump lasers, creating a polariton ‘conveyor belt’. The breaking of time-reversal symmetry caused band structures to become non-reciprocal and acquired a universal tilt. The non-reciprocal tilting was connected to the non-trivial topology of the Floquet–Bloch bands, which have a finite Chern number. Detailed characterization of the lattice potential depth and its dynamics highlighted the role of high-energy carriers in the formation of optical potential landscapes for polaritons, demonstrating the possibility of modulation faster than the polariton lifetime and opening a pathway towards Floquet engineering in polariton condensates… read more. Open Access TECHNICAL ARTICLE
Band structures of a polariton conveyor belt. Credit: Nature Photonics, 23 April 2024