NBIA Colloquium via Zoom by Albert Schliesser, NBI
Mechanics at the Quantum Limit:
Quantum Measurement and Control of Macroscopic Motion
Speaker: Albert Schliesser (NBI)
Abstract: For more than a century, Quantum Mechanics has been a tremendously successful physical theory, whose predictions have been confirmed with astounding accuracy. However, experimental tests have mostly remained limited to microscopic systems, and it is an open question how “large” a system can be and still behave quantum mechanically. Addressing this frontier, I will report in this talk on the advances in our ability to measure and control the quantum state of motion of mechanical systems visible to the bare eye.
To this end, we develop highly coherent membrane resonators which are extremely well shielded from any perturbations by their environment. We then use optical interferometry to monitor the membranes’ motion. In doing so, we directly observe the quantum “back-action” of the measurement process on the measured object, here in the form of quantum fluctuations of radiation pressure. I will discuss optimum measurement strategies, which imply noise trade-offs similar to those known from the Heisenberg microscope thought experiment, but also benefit from quantum correlations generated in the system. The information gained through such near-ideal measurements can also be used to control the quantum state, for example by applying feedback to the mechanical systems – in principle not unlike noise cancellation in modern headphones.
Beyond the fundamental interest, a goal of this research is to provide unique mechanical functionality to future quantum technologies, analogous to mechanical devices ubiquitous in today’s classical technology. Potential applications could include memories and transducers for quantum information carried by light and microwaves, or new kinds of nano-scale magnetic resonance imaging.
Brief bio-sketch: Albert Schliesser took his Master’s degree at the Technical University of Munich. In 2009, he obtained his PhD from Ludwig-Maximilians University Munich and the Max-Planck Institute of Quantum Optics, for a work on both optomechanical effects and frequency comb generators in microscale optical devices. He then did a postdoc at the École Polytechnique Fédérale de Lausanne. In 2013, he joined the Niels Bohr Institute, where he became full professor in 2016. He has since led a research group at NBI in the area of Quantum Optics and Optomechanics. He is recipient of both a Starting and a Consolidator ERC grant, a NERD grant from the Novo Nordisk Foundation, and a co-PI of the DG center Hy-Q. In 2020 he has been elected Fellow of the Optical Society of America.
To participate on Friday, click on
https://ucph-ku.zoom.us/j/61333932427
The colloquium will be moderated by Evert van Nieuwenburg and we strongly encourage you to participate actively by asking questions during the talk. Evert will briefly remind you how this can be done just before the colloquium starts