A nanofabricated structure with subwavelength thickness, known as a metasurface, shows a huge potential to facilitate the miniaturization of quantum photonic devices at the nanoscale [1]. Metasurface has allowed multiphoton state reconstruction [2] and single-photon generation [3]. This project involves the generation and manipulation of polarization-entangled photon pairs with metasurface.

One direction of this project is to generate photon pairs from a subwavelength-thick lithium niobate film patterned with nanostructured grating. Photon-pair generation from bulk nonlinear crystals is subject to phase-matching conditions. Here the phase-matching limitations are released, allowing a broad choice of nonlinear materials and the preparation of diverse quantum states.  As compared with an unpatterned thin film, a metausrface with a designed optical resonance at the degenerate wavelength can boost the efficiency of the pair generation rate by several orders of magnitude. Further steps include the preparation of polarization entanglement and application towards quantum imaging. 

The other direction of this project aims to manipulate and detect entangled photon pairs with metasurface. There is a scope for the experimental characterization of metasurface and realization of quantum state discrimination and quantum communication on an integrated metasurface.

The project is a part of the newly established ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS), https://tmos.org.au/. This is an exciting opportunity to contribute to the TMOS mission of developing the next-generation miniaturised optical systems with functionalities beyond what is conceivable today.

[1] Nat. Photonics 15, 327 (2021)

[2] Science 361, 1104 (2018).

[3] Nano Lett. 21, 4423 (2021).

Knowledge of quantum mechanics and experience in free-space optical experiments would be beneficial.