arXiv subjects

S Chaturvedi

Publications and source records attributed to S Chaturvedi.

3 recordsLinked to original sources

arXiv2019

Geometric phases for finite-dimensional systems -- the roles of Bargmann Invariants, Null Phase Curves and the Schwinger Majorana SU(2) framework

We present a study of the properties of Bargmann Invariants (BI) and Null Phase Curves (NPC) in the theory of the geometric phase for finite dimensional systems. A recent suggestion to exploit the Majorana theorem on symmetric SU(2) multispinors is combined with the Schwinger oscillator operator construction to develop efficient operator based methods to handle these problems. The BI is described using intrinsic unitary invariant angle parameters, whose algebraic properties as functions of Hilbert space dimension are analysed using elegant group theoretic methods. The BI-geometric phase connection, extended by the use of NPC's, is explored in detail, and interesting new experiments in this subject are pointed out.

quant-ph↗

arXiv2017

The Ericsson Nano-Brownian Engine in the Quantum Domain

We examine here a hitherto unchartered Ericsson motor, operating in the quantum domain. The engine is a nanoscopic system of an electron trapped in a two-dimensional parabolic well and further subjected to an external magnetic field in the third direction. The quantum-coherent cyclotron motion of the electron is de-cohered due to strong interaction with a dissipative quantum heat bath.The calculation employs two different approaches - exact functional integral representation of the partition function and quantum Langevin equations for the operators of the system. Though in equilibrium, both the approaches yield equivalent expressions for the efficiency, the Langevin method opens up further avenues for investigating time dependent properties of the nano motor.

quant-ph↗

arXiv1995

Canonical Partition Functions for Parastatistical Systems of any order

A general formula for the canonical partition function for a system obeying any statistics based on the permutation group is derived. The formula expresses the canonical partition function in terms of sums of Schur functions. The only hitherto known result due to Suranyi [ Phys. Rev. Lett. {\bf 65}, 2329 (1990)] for parasystems of order two is shown to arise as a special case of our general formula. Our results also yield all the relevant information about the structure of the Fock spaces for parasystems.

hep-th↗