Pitt-CMU Colloquium: Tom Purdy (Pitt)

Coupling Optical, Mechanical, and Microwave Systems for Quantum Sensing and Transduction Quantum information science provides a new approach to a range of challenging tasks in computing, sensing, and communication. I will present recent experiments that connect quantum systems to each other and to the classical world with sufficient fidelity to harness their full potential as sensors and transducers. Drawing on ideas from atomic physics, nanomechanics, nonlinear optics, gravitational wave detection, and precision optical metrology, my lab develops devices and techniques to couple mechanical, optical, microwave, and qubit systems. First, I will show how to turn an electro-optic modulator, a workhorse of modern classical telecommunications systems for encoding microwave signals on laser light, into a transducer capable of efficiently moving quantum information between the optical and microwave domains. Our recent results show that bulk, resonant electro-optic devices are capable of transduction efficiency approaching unity, an over six-order-of-magnitude step-up from classical telecom devices. We are currently exploring how laser light in this system can be used to manipulate and measure microwave devices in analogy to laser cooling in atomic and optomechanical systems. Next, I will discuss the optical lever, one of the simplest precision measurement techniques, with centuries-old roots in the scientific literature and still the go-to readout for modern atomic force microscopes. Despite its simplicity, a few minor modifications to the optical beam path allow optical lever detectors to operate with high efficiency and evade quantum noise, pushing it to and beyond standard quantum limits. Finally, I will highlight some of the unexpected places where acoustic waves can replace their electromagnetic counterparts in quantum sensing, including mechanical quantum memories and the acoustic analog of blackbody radiation. In one such system, sound waves on a string cool the mo