QFS2016 Book of Abstracts

Abstracts

P4.14 Observation of high-order transitions in a superconducting qubit coupled to coplanar waveguide cavity Yu-Cheng Chang, Ze-Yan Chen, Jyh-Yang Wang, Teik-Hui Lee, Teik-Hui Lee,

Myrron A. Aguila, Joshoua Esmenda and Chii-Dong Chen Institute of Physics, Academia Sinica, Taipei 115, Taiwan

Coherent interaction between a superconducting transmon quantum bit and an on-chip superconducting cavity is studied. The transmon consists of a SQUID whose transition frequency between the two lowest levels of the transmon can be tuned continuously by the applied external magnetic flux threading the SQUID loop. As this level spacing is tuned to close to the resonance frequency of the Nb superconducting cavity, the Rabi-splitting feature emerges, indicating a coherence coupling between the qubit and the cavity. In addition, the higher-order transitions involving 2nd and 3rd excitation levels and multiple photons are observed, but there are no sign of qubit-cavity coupling. P4.15 Inductively Coupled Superconducting Quantum Interference Device Transduction of Nanoelectromechanical Systems at Low Temperatures Rupert Mellor (1), Andrew Casey (1), Brian Cowan (1), Chris Lusher (1), Kunal Lulla (1,2), John Saunders (1) 1) Department of Physics, Royal Holloway, University of London, UK 2) Now at Department of Physics, Lancaster University, UK We present work on high Q Nanoelectromechanical systems (NEMS) at millikelvin temperatures, transduced via a Superconducting Quantum Interference Device (SQUID) in low magnetic fields (200mT). In this technique, the NEMS is inductively coupled to the SQUID, mounted far from the magnet, allowing flexibility in magnetic field without affecting SQUID behaviour. A SiN dobly clamped beam (300 µ m x 250nm x 100nm), has been characterised from 3K to 21mK, observing thermally driven motion. We observe tuneable feedback effects between the SQUID and the NEMS, resulting in self-sustained oscillations with stability greater than 8ppb.

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