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.