A classical model of spontaneous parametric down-conversion

Dr Girish Kulkarni, Group of Prof. Robert Boyd, Department of Physics, University of Ottawa, Canada

Leuchs-Russell Auditorium, A.1.500, Staudtstr. 2

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Spontaneous parametric down-conversion (SPDC) is a nonlinear optical process in which an incident field known as the pump interacts with a nonlinear medium to produce a pair of fields known as signal and idler. While a complete description of this process requires the fields to be quantized, there are certain important features of this process that can be modeled classically. In this talk, I will discuss a classical model in which SPDC is viewed as a difference frequency generation process between the pump and a hypothetical stochastic field that mimics the vacuum fluctuations. I will show that the model's predictions agree with our experimental measurements of the far-field profile, orbital angular momentum spectrum, and wavelength spectrum of the SPDC field for increasing pump strengths. I will then show that the model can be successfully applied to SU(1,1) interferometers and induced coherence experiments. Intriguingly, the model also correctly predicts the linear scaling of the interference visibility with object transmittance in the low-gain regime – a feature that is often regarded as a quintessential signature of the nonclassicality of induced coherence.

A preprint of this work can be found here: arXiv:2201.03842

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