Bose Institute

A Brief Summary of the Significant Scientific Contributions

Dipankar Home is one of the early Indian researchers pursuing investigations on the Foundational issues of Quantum Mechanics (QM) since 1980s – a line of study that has gradually become amenable to experimental studies as well as has become intimately related to the currently vibrant area of Quantum Information Theory and its applications.

Apart from his more than 125 Research Publications that have been cited in 20 Books, and that have Total Citation Number around 1616 (Google Scholar), Home’s notable contribution has been Two distinctive Research-level Books: “Conceptual Foundations of Quantum Physics – An Overview from Modern Perspectives” (Plenum, 1997), with a Foreword by Nobel laureate Anthony Leggett, and (ii) “Einstein’s Struggles with Quantum Theory: A Reappraisal” (Springer, 2007), co-authored with Andrew Whitaker, having a Foreword by Roger Penrose. Both these books have been peer-appreciated in Physics Today (October, 1998 and May, 2008 respectively), apart from the former being also appreciatively reviewed in The Times (London), Higher Education Supplement (25 September, 1998), Foundations of Physics, Vol. 31, pp. 855 -857 (2001), and in Progress in Quantum Electronics, Vol. 22, pp. 41-42 (1998) by some of the leading experts in the area of Quantum Foundations. These two books have Total Citation Number around 190 (Google Scholar).

Among the manifold research works of Home with his collaborators, the most significant ones are briefly mentioned as follows:

A) A hitherto unexplored connection was revealed between two profound features of QM, viz. Quantum Indistinguishability (QI) and Quantum Entanglement (QE) by invoking QI for formulating an arbitrarily efficient generic scheme that can entangle, using any spin-like variable, any two identical bosons/fermions coming from independent sources [Physical Review Letters 88, 050401 (2002)].

Having such an efficient generic scheme for generating QE is of considerable importance since QE lies at the core of Quantum Foundations and various applications of Quantum Information Theory. Furthermore, this work suggested a novel form of complementarity between particle distinguishability and the amount of entanglement generated, besides providing one of the ingredients of the seminal work by C. W. J. Beenakker et al. [Physical Review Letters 93, 020501 (2004)] which initiated studies on Free-Electron Quantum Computation.

B) The above-mentioned line of study blending QI and QE was enriched by uncovering an earlier unnoticed property of QE involving any two identical particles which has been called ‘Duality in Entanglement’ [Physical Review Letters 110, 140404 (2013)]. Importantly, this property enables studying the transition from QI to Classical Distinguishability, as well as can be an effective tool for empirically probing spects of QI for mesoscopic/macroscopic molecules without requiring to bring them together, thereby avoiding the effect of interaction between them.

For photons, this predicted property of ‘Entanglement Duality’ (involving the manifestation of polarization entanglement when the photons are labelled by different momenta, or, for the same source, manifesting momentum entanglement when the photons are labelled by polarization variables) has been experimentally verified at Tsinghua University, Beijing [New Journal of Physics 16, 083011 (2014)], followed by another experimental study at INRIM, Torino [Physical Review A 91, 062117 (2015)] using Bell measurements in order to probe some subtle aspects of our predicted ‘Entanglement Duality’.

C) A series of investigations on an intriguing fundamental Quantum Mechanical effect known as the Quantum Zeno Effect throwing light on the various critical aspects of its treatment, its wide-ranging conceptual implications and the question of its experimental realizability, culminated in a comprehensive and widely cited in-depth analysis of this effect [Annals of Physics 258, 237 (1997)].

D) A striking biomolecular example was formulated in order to empirically probe aspects of the Quantum Measurement Problem in the mesoscopic domain [Physical Review Letters 76, 2836 (1996)] by using the biochemical property of photolyase enzyme attachment to uv-absorbed DNA molecules. This work was one of the earliest of its kind, trying to use the biomolecular phenomenon in order to provide empirically relevant constraints on the various approaches seeking to address the much debated Quantum Measurement Problem.

E) Wigner’s argument seeking to demonstrate Quantum Nonlocality that was originally formulated only for bipartite states was successfully generalized for an arbitrary multipartite state, thereby providing a powerful method for obtaining multipartite Bell-type inequalities in order to probe Quantum Nonlocality of the states of multipartite systems [Physical Review A 91, 012102 (2015)]. The efficacy of such obtained multipartite Bell-type inequalities has been demonstrated for the quadripartite entangled states, thus opening up a novel direction of study in this area.

Other major research contributions of Home with his collaborators are as follows:

i) A novel manifestation of wave-particle duality of single photon states providing fresh insights into the Bohrian principle of wave particle complementarity was formulated by invoking the quantum mechanical treatment of tunneling of single photon states in the context of a double-prism device [Physics Letters A 153, 403 (1991); 168, 95 (1992)]. This proposal was experimentally realized at the Hamamatsu Photonics Central Research Laboratory, Japan [Physics Letters A 68, 1 (1992)].

ii) One of the earliest ideas for testing the fundamental property of Quantum Contextuality was formulated by introducing the notion of path-spin intraparticle entanglement as applied to a Bell-type inequality involving the path and spin variables pertaining to a single spin-1/2 particle [Physics Letters A 279, 281 (2001)]. This was experimentally verified by the neutron interferometric group at Atominstitut, Vienna [Nature 425, 45 (2003)].

iii) An earlier unexplored application of the temporal analogue of Bell’s inequality, known as the Leggett-Garg inequality (LGI), for weak interaction induced two-state oscillations pertaining to neutral kaons and neutrinos revealed an intriguing result that CP violation occurring in the case of kaon oscillation enhances the Quantum Mechanical violation of LGI, a result whose conceptual implications call for a deeper probing [Physical Review A 88, 022115 (2013)].

iv) The following research works by Home with his collaborators are also noteworthy:

  • A curious application of the Dynamical Model of Spontaneous Wave Function Collapse in the cosmological context, analyzing the role of the liberated energy associated with the wave function collapse process arising from the interaction of a fluctuating scalar field with the matter wave function [Physics Letters B 679, 167 (2009)].

  • A comprehensive and widely cited Review on Ensemble Interpretations of Quantum Mechanics [Physics Reports 210, 223 (1992)].

  • Derivation of new forms of the Leggett-type crypto-nonlocal realist inequalities [Physical Review A 84, 052115 (2011)] that are free from any geometrical constraint on the measurement settings, thereby enabling their unambiguous empirical scrutiny.

  • A novel analysis of the role of Statistical Fluctuations in Quantum Cryptography [Physical Review A 67, 022306 (2003)].

  • Formulation of a testable example showing Nonlocality of Single Photon States [Physics Letters A 209, 1 (1995)].

  • For CV, please click here .

    Back to top

    Copyright @ Swapan Das. All Rights Reserved