EE Devices Seminar- Ady Arie, Tel-Aviv University

In the process of spontaneous parametric down conversion, a pump photon spontaneously splits inside a quadratic nonlinear crystal to signal and idler photons. By either structuring the nonlinear coefficient or by shaping the pump beam, it is possible to control the correlations of the down-converted signal and idler photons in different degrees of freedom. In my presentation, I will focus on generation and application of spatially encoded entangled photons.

Specifically, we have fabricated structured nonlinear crystals for direct generation of spatially entangled signal-idler pairs, including a bi-photon Bell state in the Hermite-Gauss basis. Alternatively, by shaping the pump beam, we generated bi-photon qubits and qutrits in the Laguerre-Gauss basis. The bi photon qutrit was used to demonstrate three-dimensional entanglement-based quantum key distribution. Shaped pump beams were also used for generating high brightness N00N states, which were then used for super-resolved quantum rotation sensing. Finally, I will also discuss briefly the advantages of using spatial qudits for realizing quantum algorithms, such as the Grover search algorithm.