Speaker: Hong Qiao University of Chicago
Time: 2024-07-12 10:00-2024-07-12 11:30
Venue: RM 327, MMW Building

Abstract:

Entanglement and superposition are fundamental properties of quantum-mechanical states, with no classical counterparts. It is well-established that elementary particles, such as electrons and photons, follow the rules of quantum mechanics in the microscopic world. Over the past several decades, significant advancements have been made in quantum computing, with microwave and optical photons playing crucial roles in the development of leading quantum computing platforms, including superconducting qubits and linear photonic circuits.

This study explores the possibility of using phonons—the single quanta of sound or vibrations—as quantum information carriers instead of photons. Unlike photons, phonons are relatively macroscopic, representing collective motions of quadrillions of atoms. Through extensive research in the field of "quantum acoustics", it has been demonstrated that superconducting qubits can emit and capture single phonons when the entire system is well-isolated and cooled to near absolute zero temperatures [A. Bienfait et al., Science (2019)].

In this presentation, I will discuss our recent work from the Cleland Lab, which involves the demonstration of a phononic beam splitter element, using two superconducting qubits to fully characterize it with single phonons [H. Qiao et al., Science (2023)]. We further use the beam splitter to demonstrate two-phonon interference, a requirement for phonon two-qubit gates. This work provides a complete toolbox for linear mechanical quantum computing (LMQC) based on single quanta of sound and establishes a high-fidelity hybrid quantum computing platform integrated with superconducting qubits.

Short Bio:

Hong earned his B.S. in Physics from Peking University in 2019, where he conducted research on quantum information theory under the supervision of Prof. Qiongyi He and Prof. Heng Fan, and worked on quantum optics experiments with Prof. Yunfeng Xiao. Following a brief period of studying quantum networks, he became a Ph.D. candidate in Prof. Andrew Cleland's lab at the University of Chicago, focusing on quantum acoustics, superconducting qubits, and hybrid quantum systems.