Dr. Han Zhao
California Institute of Technology
Bridging Microwave and Optical Quantum Worlds Using Nanomechanics
Location: 1080 Physics Research Building
Faculty Host: Dan Gauthier
Abstract: Imparting quantum information from microwave onto optical frequencies and vice versa is an indispensable functionality in modern quantum technologies, underlying key breakthroughs towards the quantum version of Moore’s law. Gigahertz mechanical oscillations with the characteristic wavelength at the nanoscale couple strongly to both microwave and optical fields, hence provide the ideal intermediator that bridges the orders-of-magnitude frequency gap. This talk will showcase how properly engineered on-chip mechanical systems can be leveraged to address the outstanding challenges of quantum networking and scalable quantum computing. I will present our recent progress towards phonon-mediated quantum transduction that interconnects superconducting circuits using telecommunication-band photons. Owing to the ultra-long acoustic lifetime at millikelvin temperatures, this approach achieves percent-level transduction efficiency and sub-quanta added noise under continuous-wave optical pump, opening the door to a new era of speedup for generating long-range entanglements among distant superconducting quantum processors. Looking ahead, I will share the exciting prospect of utilizing such a transducer to build efficient quantum links across different quantum hardware systems for the "quantum Internet". The quantum coherence of photon-phonon interactions at the nanoscale also enables a unique optoelectronic interface for hybrid information processing. In the second part, I will demonstrate a cavity acousto-optic arithmetic unit that performs large-scale linear transformations in the frequency dimension of light. Equipped with unprecedented arithmetic parallelism, this prototype device marks a milestone towards a hardware-efficient integrated optical quantum computing framework harvesting the quantum advantages at room-temperature.
Bio: Han Zhao is a postdoctoral scholar at the California Institute of Technology. His current research focuses on developing a silicon electro-optomechanical quantum transducers for superconducting qubits. Previously, he was a postdoctoral researcher at the University of Washington. He received his Ph.D. from the University of Pennsylvania, where his thesis was on the applications of non-Hermitian topological physics in integrated active photonics. His research interests include the synergetic engineering of hybrid quantum devices encompassing superconducting circuits, nanomechanics and integrated photonics, with the aim to enable efficient and scalable quantum interconnects and quantum information processing.
