Light Meets Sound: Rochester Physicist Wins $1.35 Million to Fuse Photons and Phonons

At the boundary between optics and mechanics, a quiet revolution is underway, and one of its architects has just received a major vote of confidence. William Renninger, an associate professor at the University of Rochester’s Institute of Optics, has been named one of 21 new Experimental Physics Investigators by the Gordon and Betty Moore Foundation. The honor comes with $1.35 million distributed over five years, a form of flexible, mid-career funding designed to let researchers pursue ambitious, high-risk experimental questions that conventional grant structures often struggle to accommodate. Renninger’s program centers on a deceptively simple goal: finding new and more powerful ways to couple light with sound, and then using that coupling to build instruments capable of probing matter with unprecedented precision.

To understand why pairing photons with phonons is such a compelling frontier, it helps to consider what each carrier of energy does best. Photons, the individual quanta of light, are the undisputed champions of communication. They travel at the fastest speed physics allows, they interact only weakly with their surroundings, and they can carry information across intercontinental fiber networks with astonishing fidelity. Phonons, the quantized units of mechanical vibration, are the opposite in temperament. They move slowly, they are easily disturbed by heat, and they almost never travel far in ordinary materials. Yet those same liabilities translate into strengths: phonons can store energy in compact volumes, they couple naturally to nearly every other physical system, and their slow pace gives researchers a handle for manipulating and reading out quantum states that would otherwise be too fleeting to grasp.

The field that exploits this complementarity is known broadly as cavity optomechanics, and its central idea is to place mechanical motion inside an optical resonator so that light can exert exquisitely controlled forces on a vibrating object, while the vibration in turn modulates the light. When the interaction is strong enough, the two systems stop behaving as separate entities and become hybridized, sharing quantum states the way two coupled pendulums share energy. This hybrid regime is where the most exciting applications live. A mechanical oscillator entangled with an optical field could serve as a transducer, converting quantum information from one physical carrier to another. A phonon mode driven by light could act as an extremely narrow filter or delay line for microwave and optical signals. And a massive mechanical object cooled close to its quantum ground state becomes a laboratory for testing whether the strange rules of quantum mechanics survive at scales far larger than atoms.

Renninger’s laboratory has built its reputation on pushing these interactions into new regimes, and the Moore Foundation award will support a program that deliberately spans multiple physical platforms. Rather than confining the work to a single device geometry, the project aims to create light-driven sound devices and measurement methods that operate across integrated photonic chips, surface acoustic wave devices, and bulk crystalline resonators. Each platform occupies a different niche. Chip-scale devices offer tight confinement and strong light-matter interaction, making them ideal for signal processing and integration with existing photonics. Surface acoustic waves, which ripple along the surface of a piezoelectric crystal much like waves across a pond, provide a natural bridge between electrical circuits and mechanical motion, and Rochester researchers have previously explored their potential for future quantum networks. Bulk crystals, meanwhile, can host acoustic modes of exceptional purity, with phonons bouncing back and forth millions of times before dissipating, which is exactly the kind of long-lived storage that quantum technologies demand.

One of the most consequential goals of the program is the generation of strong, narrow-band acoustic responses for optical signal processing. Modern communication systems are straining under demand for bandwidth, and the ability to filter, route, and delay light using sound offers a route to processors that combine the speed of photonics with the selectivity of acoustics. Because phonons oscillate at frequencies many orders of magnitude below those of optical carriers, they provide a natural clockwork for manipulating light with fine spectral resolution. A device that converts an optical signal into a phonon, holds it briefly, and converts it back can function as a tunable delay line or a frequency-selective switch, capabilities that underpin everything from coherent communications to quantum information protocols that must synchronize photons arriving from different sources.

A second, more speculative thread reaches into fundamental physics: the search for ultralight dark matter. Cosmological and astrophysical evidence overwhelmingly indicates that most of the matter in the universe is invisible, interacting with ordinary matter only through gravity, yet its identity remains one of the deepest open questions in science. Among the many candidate particles proposed over the decades, ultralight bosons occupy a particularly tantalizing corner of parameter space. If they exist, they could behave less like particles and more like a faint, oscillating classical field that permeates everything, potentially exerting periodic forces on matter at extremely well-defined frequencies. Detecting such signals requires sensors of extraordinary sensitivity to vanishingly weak, narrow-band forces, and precision mechanical resonators coupled to optical readout are among the most promising architectures. Renninger’s project aims to evaluate and extend this sensitivity, potentially giving researchers a new class of instruments for listening to the faintest gravitational whispers of the dark sector.

The program also promises new tools for interrogating the materials themselves. Defects in crystals, atomic-scale imperfections that disrupt an otherwise regular lattice, play a decisive role in semiconductor technology, where they can either ruin a device or, when engineered deliberately, serve as qubits, single-photon sources, or sensors. Mapping where these defects sit, how they lose energy, and how they interact with their surroundings is notoriously difficult. Renninger envisions using light to control and measure mechanical motion as a way to reveal this hidden landscape, essentially turning acoustic and optical probes into microscopes for energy loss and imperfection. Such techniques could benefit the semiconductor industry, where understanding defect behavior is central to manufacturing, as well as the quantum community, where the coherence of spin qubits often hinges on the defect environment.

Perhaps the most conceptually ambitious aim is to build experimental platforms for testing how large mechanical systems behave near the limits of quantum physics. Quantum mechanics was developed to describe atoms and photons, yet there is no agreed-upon reason why it should fail at larger scales, and no consensus on where, if ever, the quantum-to-classical transition occurs. Massive mechanical oscillators, because they couple to so many environmental degrees of freedom, offer a clean testing ground. By cooling such oscillators toward their quantum ground state and then driving them with light, researchers can ask whether superposition and entanglement persist in objects containing trillions of atoms. Renninger’s stated ambition to broaden how researchers use light to control and measure motion in systems that are currently hard to reach speaks directly to this question, extending optomechanical techniques to platforms where they have not previously been practical.

Beyond the technical program, the Moore Foundation’s Experimental Physics Investigators Initiative is structured to amplify individual awards through collective benefit. The 21 new investigators are brought together as a cohort, with support for exchanging ideas, developing new collaborations, and investing in mentoring and professional development. For mid-career scientists, this model of flexible funding is often described as room to take risks, and it reflects a philosophy that the most transformative experiments frequently begin as questions too open-ended to survive a conventional proposal cycle. Renninger expressed gratitude for the foundation’s support of his research program, noting that his lab hopes to produce better tools for optical signal processing, new ways to map hidden defects and energy loss inside materials, and experimental platforms for probing quantum behavior in mechanical systems. The full list of 2026 investigators is available on the Moore Foundation website, and for the field of optomechanics, the award signals that the marriage of light and sound is now regarded as one of experimental physics’ most fertile frontiers.

Subject of Research: Cavity optomechanics: coupling photons and phonons for quantum sensing, signal processing, and fundamental physics

Article Title: Pairing light and sound to explore new frontiers in physics

Article References: Pairing light and sound to explore new frontiers in physics. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: optomechanics, photons, phonons, quantum physics, surface acoustic waves, dark matter, Moore Foundation, University of Rochester, signal processing, crystal defects, quantum sensing, experimental physics