Nonlocal Correlations between Frequency Entangled Two-Qudit States
Sacha Schwarz, University of Bern
In my talk, I will demonstrate our method to experimentally encode qudits in the energy spectrum of broadband entangled photons generated by parametric down-conversion and detected in coincidence by sum frequency generation. Employing techniques from ultrafast optics to shape fs-laser pulses, the two-photon spectrum is discretized into frequency bins. By controlling each frequency bin individually, the generation of maximally entangled two-qudit states up to d = 4 is verified through quantum state tomography. Further, due to the high flexibility of our setup in performing projective measurements, Bell parameters of different Bell scenarios with multiple inputs and outcomes are experimentally determined in the case of entangled qubits and qutrits as a function of their degree of entanglement. Subsequently, the nonlocality content of various qutrit states is further quantified by means of the distance to the local polytope and the nonlocal capacity. The latter is an alternative measure of nonlocality with a direct information-theoretic interpretation representing the minimal amount of classical communication required for simulating nonlocal correlations.
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