This is a past event.

Thursday, February 25 @ 4pm – Zoom

Seth Nelson [Advisor: Miguel Levy] will present: 

Nonreciprocity and Photon Entanglement

Magneto-Optical materials are well explored media in which the propagation of electromagnetic radiation is non-reciprocally modified by the presence of a magnetic field. There has been extensive work done with this phenomenon, however we propose to study and implement a unique effect for possible application in quantum computation. I will present a discussion of this effect. We have mathematically shown through several methods that the angles of refraction and reflection within a magneto-optical material beam splitter will be different due to the Faraday effect. This difference in angles results in the separation of the propagation directions for the left and right circular polarizations. In order to verify the effect, we propose to study its experimental implementation in magneto-optical material bismuth substituted yttrium iron garnet (BiIG). BiIG provides several advantages including transparency within telecom wavelengths and static material magnetization. This beam separation has many potential applications especially in the quantum regime where we expect to verify a nonreciprocal version of the Hong-Ou-Mandel (HOM) effect. Here the HOM effect will be used for the implementation of nonreciprocal CNOT gates for use in quantum computing.

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Dharmendra Pant [Advisor: Prof. Ranjit Pati] will present: 

Understanding Bilayer Graphene and Graphene Like Structures

Graphene is a one-atom-thick two-dimensional sheet of carbon atoms arranged in a hexagonal honeycomb lattice. Since its discovery in 2004, it has been a wonder material among researchers because of its superlative electrical and mechanical properties. Being a zero-bandgap material, its valence and conduction bands meet at the Dirac points. Bilayer graphene consists of two sheets of graphene stacked one over another. Like a single graphene sheet, the bilayer graphene is also a zero-bandgap material. The conductivity of twisted bilayer graphene changes with the angle of twists and shows a superconducting behavior at a magic angle of 1.1°. To understand the origin of such interesting behavior, we are attempting a first principles study to investigate the role of interlayer coupling in twisted bilayer quantum dots at different twisting angles. From our preliminary electronic structure analysis (without van der Waals interactions) we have observed a state of the phase transition at some angles of twist in two different size bilayer quantum dots. We are examining these results further with higher K-points sampling and calculations that takes van der Waals interactions into account. I will also present our result on graphene stacked with 2D boron nitride, which did not yield a similar energy gap dependence as observed in a bilayer graphene.