Leon Bello Title: In-situ quantum signal processing Affiliation: Princeton University (currently in the Weizmann Institute of Science)

Abstract: Textbook quantum mechanics treats measurement as a mathematical projection. In reality, measurement is a dynamical physical process subject to both fundamental constraints (such as back-action and added noise) and technical bottlenecks (such as insertion loss and circuit complexity). The interface where this process occurs--the boundary between the fragile quantum system and the robust macroscopic world--currently limits the scalability and fidelity of almost all quantum technologies. In this talk, I present a framework for in-situ quantum signal processing in superconducting circuits. I will demonstrate how we can address the interface challenge by replacing static hardware--isolators, amplifiers, and splitters--with engineered time-dependent interactions implemented directly on-chip. By parametrically driving multi-wave mixing processes, we engineer effective Hamiltonians that break reciprocity and amplify signals at the source. This architecture eliminates the need for bulky magnetic isolation, offering a scalable path toward high-fidelity, directional readout in large-scale arrays. Second, I will address the fundamental physics of analyzing these driven systems. Finite measurement bandwidth implies that our observation is inherently incomplete; we effectively "coarse-grain" over the system's fastest dynamics. To model this, I introduce a method that derives effective generators for these time-averaged observables. I will show how it allows us to capture the non-trivial effects of competing timescales in strongly driven systems, revealing deterministic corrections that are essential for understanding the limits and prospects of driven systems. Short bio: Leon Bello received his PhD in Physics from Bar-Ilan University in 2021 under the supervision of Prof. Avi Pe’er, with a focus on parametric processes for sensing and computation. He subsequently held a postdoctoral position at Princeton University with Prof. Hakan Türeci, where he worked on quantum device theory, quantum control, and computation in engineered physical systems. He is currently a postdoctoral fellow at the Weizmann Institute of Science.