CAREER: Cavity-less optomechanics with macroscopic resonances

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

Nontechnical Description: Cavity-optomechanics faces tremendous challenges of interrogating quantum mechanical oscillators of suspended structures using light at low temperature, caused by optical-absorption-driven mechanical heating and the associated quantum noise. On the other hand, implementation of dynamic modulation of light based on resonator arrays, which could lead to topological photonic states and unconventional light guiding, is facing the scaling issue of inhomogeneous resonators and modulators. Mechanical bound states in the continuum (BICs) in two-dimensional slab-on-substrate optomechanical crystals uniquely solve these challenges in the two distinct research areas. Thanks to the prohibited radiation of these mechanical BICs while being in contact with the substrate, unparalleled parametric optomechanical coupling might be achieved without introducing excess quantum noises. The large-scale resonance effect will also enhance traveling-wave acousto-optic modulations for a new paradigm of effective gauge field for photons in the continuum without using discrete resonators, leading to reconfigurable light guiding on chips and topological photonic states. The achievement of these demonstrations will enable a significant leap in programmable integrated photonic circuits, implementing quantum optomechanical protocols, and pushing the boundary between quantum and classical realms. Technical Description: The goal of this program is to demonstrate a new on-chip optomechanical architecture for macroscopic quantum optomechanics and Floquet light guiding by taking advantage of mechanical BICs. Fundamental physics involving quantum coherence and light-matter interactions at macroscopic scales are being explored, while theoretical concepts are translated to experimental demonstrations in integrated devices and systems. Trapping resonance phonons in large areas while enabling dissipation of optical-absorption-driven thermal phonons, this cavity-less optomechanical architecture might provide unprecedented cooperativity between phonons and photons, transcending the limitation of the prevailing architecture of optomechanical cavities in suspended structures. The primary focus of the project is on exploring macroscopic quantum optomechanical phenomena and time-modulated light guiding. In the first focus, radiation-pressure force will be used to cool the mechanical BICs for studying quantum phononic coherence beyond the microscopic scale, and in the second, mechanical BICs with finite Bloch momentum will be used for strong acousto-optic modulations of photonic band structure leading to Floquet light guiding. Experimental validations of these effects will be attained through the combination of physical modeling and device engineering. New regime of quantum optomechanics and Floquet photonics will be studied, aiming for fundamentally transcending the current limitations in manipulating single phonon states and dynamic modulation of light based on micro-resonators. The outcome of this program, including a new platform for optomechanics, could have a tremendous impact beyond this program including programmable optical computing, understanding quantum-to-classical transition, and enhancing quantum protocols for larger quantum networks. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.