Exceptional points and quantum entanglement via unitary and thermal dynamics

Kumar, Akhil (2021) Exceptional points and quantum entanglement via unitary and thermal dynamics. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Akhil Kumar (16MS052)) 16MS052_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

We investigated the dynamics of a qubit undergoing periodic evolution on a two-dimensional temporal space, that is part thermal and part unitary. Properties of such evolution can be studied via Non-Hermitian Floquet Hamiltonians that can be in the PT -symmetric or PT -broken phases. We map out the phase diagram of the system, along with the ex- ceptional point (EP) contours through analytical and numerical methods. We analyse the system analytically for N-cycles to observe the stroboscopic behaviour through the e�ective Floquet Hamiltonian. Our results suggest that dynamics in unitary and thermal systems are a new avenue to realize EP degeneracies. Moreover, we extend this single qubit sys- tem to a coupled two qubit system, where the qubits are in unitary and thermal dynamics respectively. We explore its dynamics with di�erent initial con�gurations, and the result shows a new possible way of creating entanglement in a bipartite system.

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