Topologically Tunable Polaritons Based on a Two-Dimensional Crystal in a Photonic Lattice

Area of Science:

• Condensed Matter Physics
• Quantum Optics
• Materials Science

Background:

• Structured optical cavities are crucial for studying lattice Hamiltonians and topological phenomena.
• In-situ tuning of topological modes in monolithic cavities is experimentally challenging.

Purpose of the Study:

• To emulate the Su-Schrieffer-Heeger (SSH) lattice Hamiltonian in a tunable open optical cavity.
• To investigate the in-situ tunability of topological modes and their properties.
• To explore the transformation of the SSH lattice into a Stark ladder.

Main Methods:

• Emulation of the SSH lattice Hamiltonian in a tunable open optical cavity.
• Strong coupling of the cavity to excitons in an integrated WS2 monolayer.
• Utilizing tilt tunability to transform the SSH lattice into a Stark ladder.

Main Results:

• Observation of a topologically protected, exponentially localized mode at a domain boundary.
• Spectral tunability of the topological mode over 80 meV.
• Direct quantification of the Zak-phase difference (1.07±0.11)π.
• Transformation of the SSH lattice into a Stark ladder, coupling defect and propagating modes.

Conclusions:

• This work presents a significant advancement in the in-situ tuning of topological lattices.
• The developed platform enables precise control and guidance of light in nonlinear photonic systems.
• Opens new avenues for on-chip manipulation of topological states of light.