• SWAPAN MANDAL

      Articles written in Pramana – Journal of Physics

    • Antibunching of photons in a coherent radiation field coupled to a non-degenerate parametric oscillator beyond rotating wave approximation

      SWAPAN MANDAL MOHOSIN ALAM MONOJIT KORA MOHAMED RIDZA WAHIDDIN

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      Under the classical (strong) pump condition, the Hamiltonian involving the signal and the idler modes of a non-degenerate parametric oscillator is exhibited. Without using the usual rotating wave approximation (RWA), the analytical solutions of the field operators are used to investigate the antibunching of photons of the input radiation field coupled to the non-degenerate parametric oscillator. By using the symbolic calculation, the antibunching of photons for both the signal and idler modes are investigated. In particular, the effects of the inclusion of rotating wave approximated terms on the antibunching of photons are clearly indicated. To substantiate the analytical results, the temporal evolution of signal photon and idler photons, and the antibunching effects of the signal and idler modes are investigated numerically by using the QuTip 3.1.0. The exact numerical results obtained by QuTip 3.1.0 matches extremely well with those of the analytical results. The present article and hence the analytical method might be of use for investigating the situations of having ultra-strongly and deep-strongly coupled systems where the possibilities of using RWA is completely ruled out.

    • Quantum phase fluctuations of coherent light coupled to a direct band-gap semiconductor

      ARJUN MUKHOPADHYAY MOHOSIN ALAM BISWAJIT SEN SWAPAN MANDAL

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      The coherent light interacting with a direct band-gap semiconductor is modelled as two coupled harmonic oscillators with Kerr-type nonlinearity in one of the oscillators. By considering the nonlinearity in the exciton mode, we derive approximate analytical solutions of the coupled differential equations involving two bosonic modes. For both photon and exciton modes which are in initial coherent states, we calculate the phase fluctuation parameters due to Carruthers and Nieto. We have used the Pegg–Barnett formalism for defining the useful phase operators. We report the increase and decrease of phase fluctuation parameters of input radiation field compared to its initial values. Effects of vacuum field on the phase fluctuation parameters are found distinctly different from their counterparts without vacuum. The complete analytical approach of the present investigation is substantiated by the numerical calculations based on QuTip.

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