| PhD Seminar

Name of the Speaker: Mr. Bhaskar Kumar (EE21D041)
Guide: Dr. Balaji Srinivasan
Co-Guide: Dr. Prabhu Rajagopal
Venue: ESB-244 (Seminar Hall)
Date/Time: 21st Aug 2025 (Thursday), 3:30 PM
Title: Study of phonon antibunching in quantum optomechanical setup using high-Q silicon nitride suspended membranes

Abstract :

Phonon antibunching, refers to the non-classical phenomenon where phonons which are quanta of mechanical vibrations—are emitted or detected with suppressed probability of simultaneous occurence. Phonons, being bosons are subject to Bose-Einstein statistics which allow unlimited occupancy of the same quantum state resulting in multiple phonons to be detected simultaneously. Conventional Phonon Blockade (CPB) structures rely on strong nonlinearity in the Nanomechanical Resonator (NAMR) to create anharmonic energy levels, blocking two-phonon states due to energy mismatch. This strong nonlinearity is very challenging to achieve experimentally and to date the experimental realization of phonon blockades remains an elusive feat.

In this work, we propose a detailed investigation using analytical models and numerical simulations to predict and optimize conditions for phonon antibunching in coupled NAMR systems through the framework of cavity optomechanical systems. These coupled resonator systems form what is known as Unconventional Phonon Blockades (UPB) which relaxes the stringent requirement of strong nonlinearity through the phenomenon of quantum interference making it more conducive for experimental realization. We propose experimental work focused on achieving ground state cooling of high-Q silicon nitride membrane in quantum optomechanical systems through sideband cooling, a critical step towards the goal of single phonon sources.