Asma Al-Qasimi

Definitions of the degree of polarization of a light beam

A necessary and sufficient condition is derived for certain ad hoc expressions that are frequently used in the literature to represent correctly the degree of polarization of a light beam.

Quantum properties and dynamics of X states

X states are a broad class of two-qubit density matrices that generalize many states of interest in the literature. In this work, we give a comprehensive account of various quantum properties of these states, such as entanglement, negativity, quantum discord and other related quantities. Moreover, we discuss the transformations that preserve their structure both in terms of continuous time evolution and discrete quantum processes.

Nonexistence of entanglement sudden death in dephasing of high NOON states.

We study the dynamics of entanglement in continuous variable quantum systems. Specifically, we study the phenomena of entanglement sudden death (ESD) in general two-mode-N-photon states undergoing pure dephasing. We show that for these circumstances, ESD never occurs. These states are generalizations of the so-called high NOON states (i.e., a superposition of N photons in the first mode, O in the second, with O photons in the first, N in the second), shown to decrease the Rayleigh limit of lambda to lambda/N, which promises great improvement in resolution of interference patterns if states with large N are physically realized [Phys. Rev. Lett.85, 2733 (2000)]. However, we show that in dephasing NOON states, the time to reach some critical visibility Vcrit, scales inversely with N2. On the practical level, this shows that as N increases, the visibility degrades much faster, which is likely to be a considerable drawback for any practical application of these states.

Properties of quasi-homogeneous isotropic electromagnetic sources

We study the properties of Quasi-Homogeneous Isotropic Electromagnetic (QuHIEM) Sources, a model for partially-coherent secondary light sources beyond the scalar and paraxial approximations. Our results include polarization properties in the far zone and the realizability condition. We demonstrate these results for sources with a degree of coherence described by Gaussians.

Rainbows in Bosonic Josephson Junctions

Optical rainbows are an example of natural focusing. Here we discuss an analogous phenomenon that occurs in the dynamics of a system of N atoms in a double well potential following a quench.

Quantifying Quantum Correlation: What is the Best Way to Measure 'Quantumness' in a System

Besides being stronger and stranger than correlations encountered in everyday life, Quantum Correlations can be useful. It is, therefore, very important to quantify them. I discuss various methods, developed by the community, to achieve that.

Measurement-Induced Disturbance for a Variety of Projector Operators

Like Discord, Measurement-Induced Disturbance (MID) is defined based on the fact that measurements disturb quantum systems. However, MID is symmetric and involves no maximizations. I investigate various MID projectors selected for realistic systems.

Properties of Quasihomogeneous Isotropic Electromagnetic Sources

We study the properties of quasihomogeneous isotropic electromagnetic sources, a model for partially-coherent secondary light sources beyond the scalar and paraxial approximations. Our results include polarization properties in the far zone and the realizability condition.

Intensity Fluctuations and Cross-Polarization in Gaussian Schell-Model Beams

We study intensity fluctuations of two light beams differing only in the degree of cross-polarization. For two model beams with same degree of coherence and same degree of polarization, the intensity fluctuations can be different.