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Q-FARM presents a Double Feature Seminar - " Ultra-low-power second-order nonlinear optics on a chip" & "Quantum Dynamics of Ultrafast Nonlinear Photonics"

Event date: 
Wednesday, April 14, 2021 - 12:00 pm
Timothy P. McKenna (Stanford University) & Ryotatsu Yanagimoto (Stanford University)

Speaker #1: Timothy P. McKenna 

Title #1: Ultra-low-power second-order nonlinear optics on a chip
Thin-film lithium niobate is a promising platform for integrated photonics because it can tightly confine light in small waveguides which allows for large interactions between light, microwaves, and mechanics. Recent advances in nanofabrication have made such high performance photonic circuits possible.  In this talk, I will present a recent demonstration of efficient frequency doubling and parametric oscillation in a thin-film lithium niobate resonator. The operating regimes of this system are controlled using the relative detuning of the intracavity resonances, and the emission frequency of parametric oscillation is tuned over one THz simply by adjusting the pump laser over a few hundreds of MHz. We also observe highly-enhanced effective third-order nonlinearities caused by cascaded second-order processes resulting in parametric oscillation.  These resonant second-order nonlinear circuits will form a crucial part of the emerging nonlinear and quantum photonics platforms.
Timothy McKenna is a senior graduate student in the group of Prof. Amir Safavi-Naeini at Stanford University where he designs nanoscale systems for quantum technologies. He enjoys waves and particles of all kinds but focuses on light and microwaves at present. He currently works on integrated nonlinear optical devices and chip-scale cryogenic transducers to network quantum computers. Previously, he worked at the Johns Hopkins Applied Physics Laboratory where he combined photonic and millimeter-wave technologies to create new systems for sensing and communication. Tim holds a B.S. from the University of Pennsylvania and an M.S. from Stanford University.
Speaker #2: Ryotatsu Yanagimoto
Title #2: Quantum Dynamics of Ultrafast Nonlinear Photonics
Abstract: Broadband optical pulses propagating in highly nonlinear nanophotonic waveguides can significantly leverage optical nonlinearity by tight temporal and spatial field confinements, promising a route towards all-optical quantum engineering and information with single-photon nonlinearities. Modeling and engineering quantum optical devices operating in this strongly interacting regime, however, pose significant theoretical challenges; a large number of frequency modes undergo non-Gaussian dynamics, whose description naïvely requires exponentially large Hilbert space. Using an example of broadband parametric downconversion, we show that such systems can exhibit rich quantum dynamics that are qualitatively different from semi-classical predictions. In the talk, we introduce a prescription based on matrix product state (MPS) representations to realize an efficient full-quantum simulation of generic pulse propagation. Specifically, we unravel the dynamics of an optical soliton, highlighting features that cannot be captured by a conventional theoretical framework.
Bio: I am a Ph.D. student in Applied Physics working at Hideo Mabuchi’s group. I am interested in AMO physics and quantum photonics in general, and my main research interest is on understanding and engineering broadband quantum dynamics of optical photons in highly nonlinear systems. I got BE in Applied Physics at the University of Tokyo, where I worked on experiments on optical lattice clocks.