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McKelvey School of Engineering

Falk on Superconducting Circuits

Wednesday, October 13 | 4:00 PM

Crow Hall, 204
Crow Hall, St. Louis, MO 63105

Superconducting circuits have been used to make scalable quantum bit (qubit) devices, with high coherence and easy addressability. Decades of development have improved these devices to the point that they can be combined into noisy intermediate-scale quantum (NISQ) processors, which have already been used to demonstrate quantum advantage over classical processors. Superconducting qubits rely on lossless transport of supercurrent in order to achieve high coherence. However, quasiparticle excitations of the superconducting state can give rise to lossy transport, causing qubit state transitions and fast decoherence. Furthermore, "bursts" of these quasiparticles from high-energy radiation (such as muon impacts) can cause correlated errors in many qubits across a chip, breaking most quantum error correction architectures. In this talk I will give an introduction to quasiparticles and where they come from. I will show recent results from my group demonstrating real-time detection of quasiparticles trapping in the Andreev states of a nanobridge Josephson junction, and explain how these measurements can be used to probe quasiparticle behavior. And I will discuss possible techniques for mitigating quasiparticle-mediated decoherence in superconducting qubits.

Please note that for all in-person events, attendees must adhere to Washington University’s public health requirements, including the latest events and meetings protocol. Guests will be required to show a successful self-screening result and wear a mask at all times. 

This colloquium will be in person. If you prefer to join via Zoom, please register at the link below.

Register to attend colloquium through Zoom.

Event Type



Arts & Sciences


Science & Technology



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Speaker Information
Eli Levenson-Falk (Hosted by Murch) from University of Southern California will be presenting the colloquium "How Supernovae Break Your Quantum Computer: Quasiparticles in Superconducting Circuits"
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