| PhD Viva

Name of the Speaker: Mr. Rana Pratap (EE14D005)
Guide: Prof. Harishankar Ramachandran
Venue: ESB-210B (Conference Hall)
Date/Time: 12th December 2023 (Tuesday), 3:00 PM
Title: Photon statistics and quantum phase distribution over the fiber-optic link in the presence of phase noise

Abstract

The significant focus of the talk is to determine when semiclassical analysis fails, and quantum analysis is essential. We first investigate the quantum description of the TW electro optic phase modulator under the effect of phase fluctuations from both the laser source and the microwave oscillator. The TW electro optic phase modulator is used either directly or in a Mach-Zehnder configuration in the QKD system. We use the results of the quantum treatment of the phase modulator to evaluate the quantum bit error rate (QBER) of the FC-QKD scheme in the presence of phase noise from a radio frequency oscillator and a laser.

The second objective of the talk is to analyze the photon statistics model and quantum phase distribution for coherent optical communication links using an in-line optical amplifier in the presence of quantum phase noise, dispersion, and phase noise of the RF oscillator. The resulting photon statistics are compared with the statistics of semiclassical models. We analyze the quantum phase distribution by considering the Wigner quasiprobability distribution for a coherent optic link. Here we investigate the broadening of the quantum phase distribution and quantum analog to the bit error rate (BER). The results of quantum models are compared with the semiclassical model. Quantum treatments of both BER and variance are found to agree with prior results for single mode amplified spontaneous emission (ASE) fields in the absence of phase noise but deviate when the effect of phase noise is considered. Including phase noise effects in the amplitude in the semiclassical treatment of BER yields a new semiclassical expression that agrees with quantum expressions to machine precision for a single-mode ASE field.