Colloquium: Saikat Guha - Photonic quantum computing and applications

Title:
Photonic quantum computing and applications

Abstract(s):
In the cluster model of quantum computing, any quantum algorithm can be implemented by an adaptive sequence of measurements at the nodes of a graph, where the nodes are qubits (photons in our case) and edges between two nodes represent entanglement. An entangled cluster in a 2D square lattice topology is known to a resource for universal quantum computing. Photons are a promising candidate for encoding qubits scalably but assembling a large photonic entangled cluster state (using photons and linear optical circuits) is a challenge, since each step relies on probabilistic operations, and losses in transmission and detection. I will describe a new proposal for cluster-model photonic quantum computing that combines ideas from recent work on "boosted" linear optics based Bell basis measurements, percolation theory and quantum error correction for photon loss. In this architecture, small photonic clusters are fused in an efficient “ballistic" fashion, i.e., without any detection-induced feedback, into a long sheet of entangled photons, which can then be re-cast into a logical square-lattice graph for quantum computing. Aside from the obvious uses in general-purpose quantum computing, I will talk about applications of photonic cluster states to a special purpose quantum processor known as quantum repeater, which will be a key enabler to a future quantum internet.

Speaker Bio(s):
Saikat Guha is an Associate Professor of Optical Sciences at the University of Arizona. He earned his B.Tech. degree in electrical engineering in 2002 from the Indian Institute of Technology Kanpur (India), followed by S.M. and Ph.D. degrees in 2004 and 2008 respectively, from the department of electrical engineering and computer science at the Massachusetts Institute of Technology. His research interests span quantum limits to optical communication and sensing, optical quantum computing, and network information theory. Guha represented India at the International Physics Olympiad in 1998, where he was awarded the European Physical Society award for the experimental component. He was a co-recipient of a NASA Tech Brief award in 2010 in recognition of his work on novel receivers for quantum imaging. His Defense Advanced Research Projects Agency Information in a Photon team won the Raytheon 2011 Excellence in Engineering and Technology Award, Raytheon's highest technical honor, for outstanding research on fundamental limits of optical communication.