Selected Student Papers

Pairing superbunching with compounded nonlinearity in a resonant transition


In this article, George Mouloudakis, a PhD student of our Department and Prof. Peter Lambropoulos, Emeritus Professor of our Department, study the response of non-linear atomic transitions driven strongly by quantized electromagnetic fields of various quantum states, exploring the role of their fluctuations on the behavior of such systems.

It has been known since the early 60’s that any non-linear light-matter interaction does not depend solely on the intensity of the light but also on its photon correlation properties. A prototype of such a non-linear process is the strong field driving of a bound-bound transition, inducing the splitting of the atomic states into doublets, a phenomenon known as “Stark splitting”. If the transition between these two bound states is also a multi-photon transition, which is inherently a non-linear process, then the system becomes “doubly non-linear”. The question that arises in this case is how such a system responds to the quantum fluctuations of the driving field?

FigureTwo-photon Stark splitting modeled with Lithium parameters. The calculation is carried out for various types of radiation fields, with increasing intensity from (a) to (d). As seen in the figure, no splitting of the profile into doublets occurs in the cases of non-coherent driving, giving rise to a single peak whose width is interestingly slightly smaller for sq. vac. driving compared to chaotic driving.

The results of this work indicate that if the driving field is characterized by photon bunching or super-bunching properties, as in the case of a chaotic or a squeezed vacuum field, respectively, the strong driving of such a doubly non-linear transition leads to counterintuitive behavior.

This work sheds light on the role of field fluctuations on highly non-linear processes, an area that is undergoing renaissance due to the rapid development of high-intensity sources of squeezed radiation.

Article: “Pairing superbunching with compounded nonlinearity in a resonant transition”, G. Mouloudakis, P. Lambropoulos, Phys. Rev. A 102, 023713 – 20 August 2020


February 2021


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