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Jun 28, 2018
06/18

Jun 28, 2018
by
Suranjana Ghosh; Raman Sharma; Prasanta K. Panigrahi

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The orthogonality of cat and displaced cat states, underlying Heisenberg limited measurement in quantum metrology, is studied in the limit of large number of states. The mesoscopic superposition of the generalized cat state is correlated with the corresponding state overlap function, controlled by the sub-Planck structures arising from phase space interference. The asymptotic expression of this overlap function is evaluated and the validity of large phase space support and distinguishability of...

Topics: Quantum Physics, Optics, Physics

Source: http://arxiv.org/abs/1507.05210

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Jun 27, 2018
06/18

Jun 27, 2018
by
Suranjana Ghosh; Utpal Roy

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Quantum sensitivity is an important issue in the field of quantum metrology where sub-Planck scale structures play crucial role in the Heisenberg limited measurement. We investigate the mesoscopic superposition structures, particularly for well-known cat-like and compass-like states, in the rotating Morse system where sub-Planck scale structures originate in the dynamics of a suitably constructed SU(2) coherent state. A detail study of the sensitivity analysis reveals that rotational coupling...

Topic: Quantum Physics

Source: http://arxiv.org/abs/1504.00370

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Sep 23, 2013
09/13

Sep 23, 2013
by
Suranjana Ghosh; Irene Marzoli

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The time evolution of a particle, caught in an infinitely deep square well, displays unexpected features, when one includes tiny relativistic effects. Indeed, even the smallest corrections to the non-relativistic quadratic spectrum manifest themselves in a dramatic way. Our theoretical analysis brings to light a completely new time scale, at which the system exhibits surprisingly perfect revivals. This longer time scale rules the system dynamics and replaces the original revival time of the...

Source: http://arxiv.org/abs/1006.2733v2

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Sep 23, 2013
09/13

Sep 23, 2013
by
Suranjana Ghosh

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A phase controlled wave packet, recently used in experiment of wave packet interferometry of adiatomic molecule, is investigated to obtain mesoscopic superposition structures, useful in quantum metrology. This analysis provides a new way of obtaining sub-Planck scale structures at smaller time scale of revival dynamics. We study a number of situations for delineating the smallest interference structures and their control by tailoring the relative phase between two subsidiary wave packets. We...

Source: http://arxiv.org/abs/1111.5112v2

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Sep 23, 2013
09/13

Sep 23, 2013
by
Utpal Roy; Suranjana Ghosh; P. K. Panigrahi; David Vitali

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We find the existence of sub-Planck scale structures in the P{\"o}schl-Teller potential, which is an exactly solvable potential with both symmetric and asymmetric features. We analyze these structures in both cases by looking at the Wigner distribution of the state evolved from an initial coherent state up to various fractional revival times. We also investigate the sensitivity to perturbations of the P{\"o}schl-Teller potential and we verify that, similar to the harmonic oscillator,...

Source: http://arxiv.org/abs/0904.0488v2

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Sep 21, 2013
09/13

Sep 21, 2013
by
Suranjana Ghosh; Utpal Roy; Claudiu Genes; David Vitali

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We study the effect of decoherence on the sub-Planck scale structures of the vibrational wave packet of a molecule. The time evolution of these wave packets is investigated under the influence of a photonic or phononic environment. We determine the master equation describing the reduced dynamics of the wave-packet and analyze the sensitivity of the sub-Planck structures against decoherence in the case of a hydrogen iodide (HI) molecule.

Source: http://arxiv.org/abs/0902.4474v3

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Sep 21, 2013
09/13

Sep 21, 2013
by
Suranjana Ghosh; J. Banerji

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We show that the time frequency analysis of the autocorrelation function is, in many ways, a more appropriate tool to resolve fractional revivals of a wave packet than the usual time domain analysis. This advantage is crucial in reconstructing the initial state of the wave packet when its coherent structure is short-lived and decays before it is fully revived. Our calculations are based on the model example of fractional revivals in a Rydberg wave packet of circular states. We end by providing...

Source: http://arxiv.org/abs/0706.1576v1

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Sep 21, 2013
09/13

Sep 21, 2013
by
Utpal Roy; Suranjana Ghosh; Kaushik Bhattacharya

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In quantum mechanics textbooks the momentum operator is defined in the Cartesian coordinates and rarely the form of the momentum operator in spherical polar coordinates is discussed. Consequently one always generalizes the Cartesian prescription to other coordinates and falls in a trap. In this work we introduce the difficulties one faces when the question of the momentum operator in general curvilinear coordinates arises. We have tried to elucidate the points related to the definition of the...

Source: http://arxiv.org/abs/0706.0924v2

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Sep 21, 2013
09/13

Sep 21, 2013
by
Raman Sharma; Suranjana Ghosh; Utpal Roy; Prasanta K. Panigrahi

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The orthogonality of cat and displaced cat states, underlying Heisenberg limited measurement in quantum metrology, is studied in the limit of large number of states. The asymptotic expression for the corresponding state overlap function, controlled by the sub-Planck structures arising from phase space interference, is obtained exactly. The validity of large phase space support, in which context the asymptotic limit is achieved, is discussed in detail. For large number of coherent states,...

Source: http://arxiv.org/abs/1008.0630v2

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Sep 19, 2013
09/13

Sep 19, 2013
by
Suranjana Ghosh; Aravind Chiruvelli; J. Banerji; P. K. Panigrahi

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We demonstrate the possibility of realizing sub-Planck-scale structures in the mesoscopic superposition of molecular wave packets involving vibrational levels. The time evolution of the wave packet, taken here as the SU(2) coherent state of the Morse potential describing hydrogen iodide molecules, produces macroscopicquantum- superposition-like states, responsible for the above phenomenon. We investigate the phase-space dynamics of the coherent state through the Wigner function approach and...

Source: http://arxiv.org/abs/quant-ph/0507082v2

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Sep 18, 2013
09/13

Sep 18, 2013
by
Utpal Roy; Suranjana Ghosh; T. Shreecharan; Kaushik Bhattacharya

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In quantum mechanics textbooks the momentum operator is defined in the Cartesian coordinates and rarely the form of the momentum operator in spherical polar coordinates is discussed. Consequently one always generalizes the Cartesian prescription to other coordinates and falls in a trap. In this work we introduce the difficulties one faces when the question of the momentum operator in spherical polar coordinate comes. We have tried to point out most of the elementary quantum mechanical results,...

Source: http://arxiv.org/abs/0704.0373v1