Dynamically Encircling an Exceptional Point in a Real Quantum System

Dynamically Encircling Exceptional Points: Exact Evolution and Polarization State Conversion.

We show that a two-level non-Hermitian Hamiltonian with constant off-diagonal exchange elements can be analyzed exactly when the underlying exceptional point is perfectly encircled in the complex plane. The state evolution of this system is explicitly obtained in terms of an ensuing transfer matrix, even for large encirclements, regardless of adiabatic conditions. Our results clearly explain th...

Observation of an exceptional point in a chaotic optical microcavity.

We present spectroscopic observation of an exceptional point or the transition point between mode crossing and avoided mode crossing of neighboring quasieigenmodes in a chaotic optical microcavity of a large size parameter. The transition to the avoided mode crossing was impeded until the degree of deformation exceeded a threshold deformation owing to the system's openness also enhanced by the ...

VFS Interceptor: Dynamically Tracing File System Operations in real environments

File system traces have been used for file system evaluation, user behavior analysis, file system debugging and intrusion detection. Current file system tracing tools are hardly applicable in real environments, because they require restarting the applications or are designed for specific kinds of file systems. We developed VFS Interceptor, a low-overhead tool for capturing file system traces dy...

Coherent Control of Quantum Entropy via Quantum Interference in a Four-Level Atomic System

The time evaluation of quantum entropy in a four-level double- type atomic system is theoretically investigated. Quantum entanglement of the atom and its spontaneous emission fields is then discussed via quantum entropy. It is found that the degree of entanglement can be increased by the quantum interference induced by spontaneous emission. The phase dependence of the atom-field entanglement is...

An Automatic Real Time Impedance Matching System for Use in an RF Electrostatics Accelerator Ion Source