The variation in phase of the resultant field being non-linearly related to the changes in phase difference between the interfering complex fields, the ensuing enhancement in sensitivity for phase detection in optical metrology is achieved.

Asymmetry in the object is used as a tool to eliminate the twin-image problem. By carrying out the simulations as well as the experiment, the validity of the proposed scheme has been proven. The proposed method only requires calculating the object support information. For most of the objects, the support information can be retrieved from the object autocorrelation itself without requiring additional measurements.

A novel method is proposed and demonstrated experimentally to retrieve the 2D as well as the 3D complex object from its autocorrelation. The method utilizes edge point referencing, therefore, does not require any separate reference to record the hologram. Being common-path, it is robust to external vibrations. The employment of the amplitude shifting in the proposed setup as opposed to phase shifting also avoids using expensive components required to perform phase shifting operation.

This work improves upon the best known theoretical limits of phase sensitivity as obtained through intensity measurements in a Mach-Zehnder interferometer.

This work resolves the separability/entanglement issue exactly for a class of bipartite states.

The superposition principle applies to several physical problems. When the problem involves two or more degrees of freedom, the notion of entanglement emerges, as elucidated by Erwin Schroedinger in 1935. Quantum information processing, quantum communication, and quantum computation, have their basis on entanglement, a consequence of the superposition principle. An even more elementary consequence of the superposition principle, as seen in optics

We have found the quadrature operator eigenstates and wavefunctions for the general f-deformed oscillators. We have defined the f-deformed quadrature operator with the help of the homodyne detection method and represented its eigenstates in the f-deformed Fock state basis. This allowed us to produce a recurrence relation for the wavefunctions, which in turn allowed us to discover a new class of orthogonal polynomials. These new polynomials enabled us to represent the excited state wavefunctions of the f-oscillators in terms of the ground state wavefunction.

We have studied the squeezing properties of arbitrary numbers of superpositions of various squeezed states such as squeezed vacuum state, photon-added coherent states, and two mode squeezed vacuum state. We have considered two superpositions: the first kind and the second kind. In the case of the first kind, the superpositions of squeezed states do not show both squeezing and higher-order squeezing of all orders. This is found to be true for any state which has quadrature squeezing and multi-mode squeezed states.

The dynamics of quantum systems play an essential role in quantum information processing and computing. We have studied the dynamics of superposition of wavepackets evolving under different nonlinear Hamiltonians corresponding to Kerr medium, Morse oscillator, and bosonic Josephson junction. We have shown that quantum systems' periodic, quasi-periodic, ergodic, and chaotic dynamics can change drastically if we change just the initial state to its superposition by keeping all other system parameters the same.