In-situ quantum signal processing

by Dr. (candidate) Leon Bello

Princeton

at Condensed Matter Seminar

Mon, 20 Apr 2026, 11:10
Sacta-Rashi Building for Physics (54), room 207

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.

Created on 02-03-2026 by Bar Lev, Yevgeny (ybarlev)
Updaded on 04-03-2026 by Bar Lev, Yevgeny (ybarlev)