Junior Quantum Seminar - Manel Bosch Aguilera (University of Basel)

Please join us for the Junior Quantum Seminar with Manel Bosch Aguilera from the Quantum Optics lab, Department of Physics, University of Basel who will give the talk "When Quantum Noise Dominates Experiments: From Certification to Control" on Tuesday February 17th from 10h30-12h.

PLEASE NOTE: The Junior Quantum Series are for gathering  the junior quantum community of master's students, PhDs and post-docs at EPFL, to create a non-judgmental space were scientific ideas can be shared between peers. This event is not for Professors or senior researchers. 

ABTRACT: 
What does it mean for a light–matter system to operate at the quantum limit?
Rather than referring to minimal noise or ultimate sensitivity, one can adopt an operational definition in which a system is quantum-noise limited when its dynamics are dominated by quantum backaction, as opposed to thermal or technical noise. This condition is quantified by a quantum cooperativity Cq > 1. In this regime, quantum fluctuations of light become the primary source of noise, and their presence can be directly certified through correlations in the output field.
In the first part of this talk, I will discuss and show how this notion of operating at the quantum limit arises in light–mechanical interfaces, where vacuum fluctuations of the optical field dominate the dynamics of a nanomechanical membrane and lead to observable signatures such as ponderomotive squeezing of light. Once quantum noise becomes the dominant factor, a natural question follows: can this intrinsically quantum object—the noise itself—be processed and controlled in a useful way?
In the second part, I will show how a technique known as coherent feedback provides a route to reshaping quantum noise without measurement. By avoiding measurement and processing the optical field within a coherent feedback loop, this approach preserves quantum correlations and allows them to interfere coherently, thereby engineering an effective reservoir with tunable noise correlations. I will present experimental results demonstrating dynamical control of a mechanical oscillator and cooling beyond the standard limits of cavity dynamical backaction in the unresolved-sideband regime.

BIO: 
Manel Bosch Aguilera studied Physics at the University of Barcelona and obtained his PhD at Laboratoire Kastler Brossel in Paris, where he worked on ultracold atom experiments investigating dissipation and coherence in many-body quantum systems in optical lattices. He is currently a postdoctoral researcher at the University of Basel, where his research focuses on coherent feedback and the integration of optomechanics with cold atom systems.