PHYS838C Seminar: Jarryd Allyn Horn/Aaron Somoroff

Mon, Nov 29, 2021 4:00 pm - 5:30 pm
Toll Physics Rm 1201


Speaker1 : Jarryd Allyn Horn
Advisor: Johnpierre Paglione

Title: Superconducting and normal state properties of Ni-Bi binary system

Abstract: Superconductivity in the bismuth-nickel system has been of interest due to both the discovery of triplet p-wave superconductivity in bilayer films and the possible competition between superconductivity and magnetic order that has been measured in single-crystal NiBi3. While previous literature suggests that the presence of amorphous nickel may be the source of the previously reported ferromagnetic order in NiBi3, the effect of bismuth impurities on the electronic properties are rarely addressed. Understanding the role of these extrinsic effects calls for a more careful investigation of the electronic properties of NiBi3. In order to address this, we have grown NiBi3 samples by bismuth flux (as have all previously reported NiBi3 single crystal samples) as well as by chemical vapor transport (CVT). In this talk, I present magneto transport studies of flux- and CVT-grown NiBi3 samples which reveal large discrepancies in the electronic properties both between samples and between different sections of the same sample that suggest that bismuth impurities play a significant role in the normal state and superconducting properties of NiBi3. In addition,  will also report on recent measurements of the superconducting and normal state properties of NiBi grown by Bismuth flux.

Speaker 2: Aaron Somoroff
Advisor: Vladimir Manucharyan

Title: Quantum Computing with Fluxonium

Abstract: Among the main obstacles in realizing a quantum processor based on superconducting circuits are increasing quantum coherence times and the anharmonicity of the spectrum. I report our group's progress in improving coherence and control of fluxonium superconducting circuits with optimization of the circuit's spectrum and enhancements in fabrication. I demonstrate a device with coherence time T2 exceeding 1 millisecond and an average single qubit gate fidelity greater than 99.99% [1]. This coherence time is still limited by dielectric loss and can be improved by further mitigating material losses. The high gate fidelity is readily achievable due to the high anharmonicity inherent to fluxonium. Finally, I will present our recent work on scaling up from the single-qubit level to demonstrating two-qubit gates with capacitively coupled fluxonium circuits [2].

[1] A. Somoroff et al. arXiv:2103.08578 (2021)
[2] Q. Ficheux et al. Phys. Rev. X 11, 021026 (2021)

Note: there will NOT be receptions prior to the talk until further notice.