Lorenzo Magrini (University of Vienna)

Abstract:

The Heisenberg uncertainty principle establishes the frontier to the quantum realm. The position of a particle, the spin of an atom, the energy of a photon can only be known with finite precision. Realizing measurements close to this limit requires high efficiency and good environmental isolation. These are challenging tasks, especially with macroscopic systems and at room temperature. In this talk I will describe how the motion of a glass sphere (150 nm diameter) levitated at room temperature can be measured and controlled close to this quantum limit. This is achieved by confocal microscopy, which, together with optimal control theory allows us to track the quantum trajectory of the particle in real time and to use feedback to reduce its energy to the quantum ground state.  Finally I will show how this efficient quantum measurement is also used to observe light squeezing by radiation pressure forces on the oscillating particle even without an optical resonator.  Achieving this level of quantum control by measurement and feedback on a levitated system that is made of billions of atoms and at room temperature represents an important step for the development of extraordinary force and impulse sensors and will perhaps help future experiments addressing some of the most intriguing open questions in fundamental physics.

Bio

Lorenzo Magrini is a Postdoctoral researcher at the University of Vienna where he recently completed his Ph.D. in Physics with a thesis on quantum control of levitated nanoparticles. His most recent work was published in Nature and Optica. Before joining the group of Prof. Aspelmeyer in Vienna he graduated with a master degree in Physics at the University of Rome "La Sapienza", with particular focus in quantum optics and quantum information.

Boxed lunches will be served immediately following the talk, outdoors in the Varian courtyard. No food is allowed inside the seminar room. RSVP required. 

Zoom link  Zoom Meeting ID: 914 8268 2357; Password: 999112.