MSE Seminar: Zheshen Zhang

"Quantum Information Processing Using Optical Materials"

Thursday, May 4, 2017
9:30-10:30 a.m., Harshbarger 332

Abstract:

Optical materials lie at the heart of many forms of quantum information processing. In particular, light interacting with nonlinear optical materials can produce nonclassical phenomena beneficial to a variety of applications ranging from secure communication to high-performance computing. The nonclassical states of light have also been employed in quantum sensors to substantially outperform their classical counterparts. Nonclassical states, however, are fragile as they are easily destroyed by environmental loss and noise, limiting the value of quantum sensors in many practical situations.

In the first part of this talk, Zhang will present his team's recent work on quantum illumination: a robust sensing paradigm that uses nonlinear optical materials to produce broadband entanglement and to perform ultra-sensitive measurements. In a target-detection experiment using quantum illumination, they demonstrated an entanglement-enabled signal-to-noise-ratio gain over the optimum classical sensor. He'll then discuss a theoretical proposal for the optimum quantum-illumination receiver based on single-photon-level nonlinear optical materials. The combined efforts of material scientists and quantum-optics researchers could lead to sensing and imaging at ultimate precision limits.

The second part of this talk is dedicated to quantum communication and Zhang's joint work on the design and characterization of silicon-photonic devices for quantum communication. Together with professor Dirk Englund of MIT's Quantum Photonics Laboratory, they fabricated on-chip active ring resonators for encoding and exploited superconducting WiS2 nanowires for single-photon detection. As well they successfully implemented the coherent-one-way protocol using the silicon-photonic chip, paving the way for high-rate quantum communication at low cost. Before closing, promising prospects for quantum information processing with new materials will be discussed. In particular, extraordinary properties of nanomaterials would give rise to long sought quantum-information-processing functionalities including deterministic multi-photon entanglement generation for photonic quantum computing, quantum repeaters for the quantum Internet, and quantum-limited measurements for ultra-precise sensing.

Biography:

Zheshen Zhang is a research scientist at the Massachusetts Institute of Technology. His research interests cover a wide swath of the theoretical and experimental aspects of quantum information processing using novel optical and nanomaterials, high-rate quantum-secured communications at long distances, and robust quantum-enhanced metrology for ultra-precise sensing and imaging. In addition to his research activities, Zhang has taught courses at MIT, including "Signals, Systems, and Inference" and "Quantum Optical Communication." He is a graduate of the Georgia Institute of Technology, where he received his doctorate degree.

University of Arizona College of Engineering