LASSP & AEP Seminar by Britton Plourde (Syracuse University)

Britton Plourde
Professor of Physics
Syracuse University

Protecting Superconducting Qubits from Environmental Poisoning

Superconducting circuits are an attractive system for forming qubits in a quantum computer because of the natural energy gap to excitations in the superconductor. However, experimentally it is observed that superconducting qubits have excitations above the superconducting ground state, known as quasiparticles, at a density that is many orders of magnitude above the expected equilibrium level. These quasiparticles are dissipative and can directly impact qubit coherence; in some cases, quasiparticle poisoning bursts can lead to correlated errors between qubits across an array, a process that is fatal to quantum error correction schemes. Quasiparticles can be generated by a range of energy-deposition sources, including photons from the qubit environment with energy above the superconducting gap, or the impact of high-energy particles from background radioactivity or cosmic ray muons. Following an overview of these various quasiparticle poisoning mechanisms, I will describe two recent experiments: one studying absorption of photons by spurious antenna modes of qubit structures, the other measuring correlated phonon-mediated quasiparticle poisoning in multiqubit chips in the aftermath of particle impacts. I will discuss strategies for mitigating these poisoning effects for the implementation of future fault-tolerant quantum processors.

Hosted by Valla Fatemi

Pizza served starting at 12:10 p.m.
Please bring your own beverage

For those who cannot attend in person but would like to see the seminar, livestream only will be available via Zoom:
https://cornell.zoom.us/j/98722799978?pwd=OEdYdGpWYjVuSHh2Ry82NGw3T3ZZQT09
Webinar ID: 987 2279 9978
Passcode: 8235