Atomic Hyperentanglement: Generation and Applications

Abstract

Quantum mechanics is entirely counterintuitive and exhibits a multitude of mysterious traits. In this entanglement is one of the earliest and most debated mystery highlighting nonlocality and anti-realism at its zenith. This phenomenon at one side helped to clear philosophical foundations of the theory whereas at the other end, the same phenomenon is being exploited for protocols of quantum information processing (QIP) and quantum communication. Most of these earlier entanglement generation and applications research employed the single qubit while minimizing physical resources as well as the systems with long decoherence times. Exploration of hyperentangled state is one of the milestones towards this quantum revolution because hyperentangled states tremendously boost quantum information and communication capacity due to their high information content per quantum entity. Till now, mostly the engineering and manipulation of such states were, however, limited to the photonic systems only. In the present thesis, we propose the schemes for atomic hyperentanglement generation and applications through applying state of the art tool of Atomic Bragg Diffraction (ABD). We present entangled states consisting of atomic internal energy levels as well as atomic external momenta states for generation of atomic hypersuperposition, hyperentangled cluster-, Bell- and GHZ-states engineered deterministically through resonant and off-resonant Bragg diffraction of neutral twolevel atoms in conjunction with semi-classical atom-field interaction along classical momenta axes. Further we propose Remote State Preparation through these atomic hyperentangled states and prepare upto N-atoms state remotely. Our RSP scheme certainly offers high capacity quantum communication with good fidelity as these atomic hyperentangled states have minimum risk of decoherence and provide evident benefits of full controllability along with extremely high detection efficiency over the counterpart photonic states. We have also employed an atomic hypersuperposition state, duly pre- and post-selected, to investigate Quantum Cheshire Cat (QCC) paradox and proposed an Atomic Cheshire Cat (ACC) that strangely enough exhibit energy signature of atom in that arm of ABD interferometer where no atom is detected in momentum space. Finally thesis concludes with a general discussion as well as marking the feasibility of presented proposals for applications in quantum communications and in explorations related to foundational issues of quantum mechanics.