arXiv subjects
Publications and source records attributed to P. Anantha Lakshmi.
A detailed analysis highlighting the effect of optomechanical non-linearity on the dynamical evolution of a hybrid electro-optomechanical system (EOMS) is presented. The study, conducted over a wide range of parameter regime reveals that the quadratic coupling term significantly alters the dynamics of the system and thus cannot be ignored for any potential applications.
We demonstrate coherent control of optomechanically induced transparency and Fano resonances in a four mirror macroscopic optomechanical cavity, with two movable mirrors, each driven by an external mechanical pump. The variable control of the amplitude and phase of the coherent mechanical pumps provides a means of tuning the shape and nature of the Fano profiles. Further, our scheme shows the occurrence of tunable optomechanical features, even at very low mechanical driving field amplitudes, in macroscopic optomechanical cavities.
We demonstrate that light quanta of well defined characteristics can be generated in a coupled two-level system of three atoms. The quantum nature of light is controlled by the entanglement structure, discord, and monogamy of the system which leads to sub and superradiant behavior as well as sub-Poissonian statistics, at lower temperatures. Two distinct phases with different entanglement characteristics are observed with uniform radiation in one case and the other displaying highly focused and anisotropic radiation in far field regime. At higher temperatures, sub and superradiant light is found to persist in the absence of entanglement but with non-zero quantum discord, showing bunching of photons. It is shown that the radiation intensity can be a precise estimator of the inter-atomic distance of coupled two-level atomic systems. Our investigation shows for the first time, the three body correlation in the form of `monogamy score' controlling sub and superradiant nature of radiation intensity.
We investigate the super and sub-radiance characteristics of the radiation emitted from a system of three two-level atoms, in the GHZ and W-states. The dipolar coupling between atoms leads to two distinct configurations, one in which the three atoms are on a line, and the other in a closed loop form, wherein each atom interacts with both its neighbours. The quantum statistical properties of the emitted radiation show distinctly different characteristics for the GHZ and W-states resulting from the above configurations. The far-field radiation pattern also shows distinct differences between differently entangled states, making it possible for optical probing of entangled states.
We study the intensity-intensity correlations of the radiation emitted on probe transition in a three level cascade electromagnetically induced transparency (EIT) scheme. By applying an incoherent pump, we also monitor further changes in the characteristics of the emitted radiation. It is found that application of even a very weak incoherent pump can significantly alter the characteristics of the emitted radiation, even though the EIT characteristics remain unaltered. Our study demonstrates that for certain range of parameter values, the two photon correlation function in the probe transition oscillates between classical and non-classical domains.
The behaviour of a system of two two-level atoms, both identical as well as non-identical, under the influence of a continuously varying dipole-dipole coupling parameter for a wide range of other parameters such as the atomic level separations and the coupling strength of the external radiation field is explored. A detailed analysis of the behaviour of various level populations and some of the atomic coherences is presented. The influence of the competing effects between the Rabi field strength and the dipole dipole interaction on the two photon absorption probability is explored in detail both for identical as well as non-identical atoms. There are significant variations in the behaviour of identical and non-identical atoms as a function of the dipole coupling strength, even for small amounts of non-identity of the atoms, which in this study is incorporated through the atomic level separations.
We show efficient electro-optic modulation in a subwavelength gap-plasmon waveguide (GPW) formed by an electro-optic polymer with metal coatings. The proposed device is studied in the attenuated total reflection and end-fire configurations. In dealing with the end-fire configuration we used a taper from a micron sized guide to the GPW. The structure is shown to exhibit large phase accumulation over short distances, controllable by the applied modulating voltage.
A recently developed wavelet based approach is employed to characterize the scaling behavior of spectral fluctuations of random matrix ensembles, as well as complex atomic systems. Our study clearly reveals anti-persistent behavior and supports the Fourier power spectral analysis. It also finds evidence for multi-fractal nature in the atomic spectra. The multi-resolution and localization nature of the discrete wavelets ideally characterizes the fluctuations in these time series, some of which are not stationary.