In-situ quantum signal processing

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.

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.