In the past 5-6 years, there have been path-breaking developments in Quantum Information Processing(QIP) that help to understand how fundamental ideas in quantum mechanics can dramatically facilitate information processing. I have been actively involved with theoretical as well as collaborative experimental research in this area. A few of my research contributions thus far include: the design of quantum algorithms that explore the role of entanglement in quantum computation, quantum dissipation and its control, optical schemes for quantum computers and NMR implementations of quantum information processors. Quantum computers when functional, are expected to qualitatively outperform their classical counterparts. However, it is still not clear what gives quantum computers their exponential computational advantage. It has been conjectured that it is quantum entanglement which plays a crucial role. Characterising quantum entanglement and tracing its exact role in quantum algorithms remains a challenging open problem. I have worked on issues related to quantum entanglement in the context of the Deutsch-Jozsa algorithm and Parity Determining algorithm. It is known that the entanglement of a two-qubit quantum state can be completely quantified. However, quantifying measures of multi-qubit entanglement and investigating its robustness is a theoretical challenge even today. Such studies will help distinguish the boundary between classical and intrinsically quantum behaviour and its connection with the computational advantage of a quantum computer.
Optics has been an important test-bed for novel and counterintuitive aspects of quantum theory and Gaussian states with Gaussian-Wigner distribution functions play an important role. They are a family which can be easily generated and manipulated in the laboratory and have members from classical-like states to maximally entangled ones. This particular family is expected to play a very important role in quantum information processing for continuous variables (an area which is beginning to emerge). Recently, linear quantum optical schemes have been proposed where quantum gates are implemented in a probabilistic way using linear optical elements. The physical schemes are attractive because of the ease with which linear optical elements can be handled. Dissipation destroys quantum information and hence its study and control is important. We have explored the effect of dissipation in the context of Gaussian states, and are developing methods to improve the robustness of QIP using such states.
I have been involved with the NMR implementation of quantum algorithms in a major way in the past four years. New conceptual and experimental breakthroughs are required and collaborative work between experimentalists and theorists is needed to come up with scalable models for NMR quantum computing.
I have been interested in foundational issues in quantum mechanics, namely quantum nonlocality, quantum measurement and interpretations of quantum mechanics. I plan on continuing my investigations of these issues, mainly through exploring the quantum aspects of information processing.
I have also been working on developing new pedagogical tools for teaching physics. In particular I am interested in developing new ways of teaching Quantum Mechanics from a quantum information theoretic point of view.