Engineering multipartite entanglement in nonlinear photonic crystals

Prof. Alessandra Gatti, Università dell’ Insubria, Como, Italy
Leuchs-Russell Auditorium, A.1.500, Staudtstr. 2
Location details


This seminar analyzes the quantum state of twin-photon generated by parametric down-conversion in a nonlinear photonic crystal (NPC), with a periodic modulation of the nonlinear susceptibility in 2 dimensions. The peculiarities of this source derive from the multiple possibilities of quasi-phase matching, supported by the multiplicity of noncollinear vectors of the 2D pattern, and from the existence of shared modes characterized by a tripartite coupling, where interesting path-entangled quantum states can be realized. 
The interplay between the pump spatial degrees of freedom and the nonlinear pattern enriches the possibilities: as recently demonstrated [1], by properly modulating the transverse phase of the pump, a peculiar resonance effect takes place with a sudden boosts of the intensities of shared modes. At the same time, the tripartite entanglement turns into a four-mode entangled state, dominated by the Golden Ratio of the segment [2].  The curious appearance of this famous number will be discussed in connection with an analogy with the Fibonacci series. A transverse modulation of the pump intensity opens the relevant possibility of engineering the state [3]. In condition of spatial resonance we will show that the source enables a flexible interference of squeezed states, without the need of an external beam splitter, where both the squeezing amplitudes and mixing coefficients can be reconfigured by acting on the pump pattern.

[1] O.Jedrkiewicz, A. Gatti, E. Brambilla, M. Levenius, G. Tamošauskas, K. Gallo, Sci. Rep. 8, 1 (2018).
[2] A. Gatti, E. Brambilla, K. Gallo, O. Jedrkiewicz, Phys. Rev. A 98, 053827 (2018).
[3] E. Brambilla and A. Gatti, Opt. Expr. 27,30233 (2019)

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