Ushnish Ray

uray@caltech.edu

  Link to my CV.

I received my Bachelors degree from Colgate University, NY in 2008, graduating Summa  Cum Laude with High Honors in both Physics and Computer Science. Following this, I received a fellowship from the Physics department at the University of Illinois at Urbana-Champaign to pursue a Ph.D. I received my degree in 2015, having spent two years in experimental Atomic-Molecular-Optical (AMO) physics research and five years at the Institute of Condensed Matter Theory under the auspices of Dr. David Ceperley.


My experience with the two different approaches (viz., experiment and theory), allowed me to appreciate the importance of the different types of tools needed to address frontier questions. So, while my core approach to physics problems is a theoretical one, involving the use of both analytical and computational techniques, I also endeavor to collaborate closely with experiments in order gain insight into challenging problems. 


My dissertation was focused on studying the effects of disorder on quantum phases such as superfluids. Disorder-induced phenomena entails some of the most difficult problems in physics and are rife with open questions. The field of artificial materials constitutes a recent innovation that uses traditional AMO approaches to delve into fundamental questions in Condensed Matter (CM). The synthesis of such materials have allowed for a novel synergistic approach between experiment and theory to gain insights into disordered systems. My collaborative effort with Dr. Brian DeMarco's experimental group at UIUC undertook a comprehensive study of the  strongly correlated physics  in the presence of disorder in a Bosonic system. The project entailed some of the largest  Quantum Monte-Carlo simulations  to date, which were performed on supercomputers such as  Titan


During my time in Dr. Garnet Chan's group as a postdoctoral fellow, I worked in two important areas of physics. The first is in the area of non-equilibrium classical systems. Such systems are ubiquitous in nature, including processes as diverse as heat flow in nanotubes, flocking of birds, chemical kinetics, dynamics of ribosomes on m-RNA, growth of cancer cells etc.  The properties of the rare fluctuations of such systems are incredibly important as they encode mechanisms through which a system undergoes spontaneous change and by which it responds to external perturbations. Our work, done in collaboration with Dr. David Limmer (UC-Berkeley), exploits a connection between quantum ground state calculations and non-equilibrium statistical mechanics to arrive at a novel sampling technique. We showed that much like in quantum ground state calculations, it is possible to construct a hierarchy of approximate solutions for nonequilibrium stationary states that can then be used to compute properties of rare fluctuations efficiently. Our work opens the door to studying larger systems in fields of non-equilibrium transport, active matter, biological systems, and chemical kinetics for longer times, with increased molecular resolution.


The second area of research is in the context of strongly correlated electronic systems such as high temperature superconductors. I have been involved in the development and extension of Density Matrix Embedding Theory (DMET) to tackle models that support superconductivity. My longterm interest is to use the framework that I have developed to study the interplay of disorder and strong correlations in electronic systems.  I am keenly interested in understanding the role of strong correlation and disorder in more exotic quantum scenarios such  as topological systems and heavy-Fermions. 


Apart from fundamental research, I am also interested in computational and other technologies (such as control systems), including novel implementations of neural networks, network security and so forth. I am always on the look out for fun side projects in different contexts, as I think a hybrid approach towards learning keeps my mind engaged and enables me to think non-linearly and make global connections.


Outside of work, I enjoy socializing and communicating with people from different backgrounds. I particularly enjoy explaining physics and the "quantum-classical connection" to non-experts. I find it very illuminating to work through and adapt to another person's way of thinking in order to convey challenging concepts. Playing with my dog, reading, Tango, movies, cooking, food and wine are my immediate avenues of solace and relaxation. I also enjoy traveling and hiking.