September 2022

Abstracts of the QSIT Lunch Seminar, Thursday, September 1, 2022

Towards a Bulk Acoustic Quantum Transducer

Maxwell Drimmer - Hybrid Quantum Systems Group (Chu group), ETH Zurich

A low-noise, efficient, bi-directional microwave-to-optical transducer could connect superconducting circuits in distant dilution refrigerators, offering a promising route towards powerful, large-scale quantum computers and networks. We present our advances in developing a device in which a Bulk Acoustic Wave (BAW) resonator mediates interactions between the microwave field of a transmon qubit and a telecom-frequency mode of a Fabry-Perot cavity. We discuss the design challenges of building the cryogenic optomechanical cavity, in particular thermal misalignment and isolation against dilution refrigerator vibrations, and present our first observation of optomechanical coupling and mode thermometry. We also detail our strategy for minimizing the amount of stray optical radiation that impinges on the superconductor. We show results from an experiment that studies quasiparticle generation due to laser light and its detrimental effects on our microwave circuitry.

Towards fast entangling operations in trapped ions with integrated photonics

Alfredo Ricci - Trapped Ion Quantum Information Group (Home group), ETH Zurich

We present the control of a qubit transition in one and two trapped calcium ions in a standing wave generated using integrated photonics. In this configuration, we achieve maximal motional coupling of the ions, while minimizing their carrier coupling allowing us to achieve faster entangling gates. Furthermore, the use of integrated photonics provides excellent passive phase stability of the beams generating the standing wave, therefore, minimizing the complexity of the system while increasing its scalability.