Title: Quantum cavity optomechanics at microwave frequencies
Speaker: Prof. Mika Sillanpää
Affiliation: Department of Applied Physics, Aalto University, Finland
Date: Friday April 30th
Please contact to the department for the Zoom Meeting information details.
Abstract: Mechanical oscillators affected by radiation pressure forces allow to address fundamental questions on quantum properties of moving objects, or, to explore quantum limits in measurement and amplification. A interesting setup for the purpose consists of superconducting on-chip microwave cavities coupled to a micromechanical vibrating membranes. After an introduction to the topic, we will discuss our recent work where we study the collective modes of two aluminum drumhead oscillators, each independently coupled to a microwave cavity. We show how one can carry out quantum non-demolition measurements of the collective quadratures of the vibrations, and achieve an evasion of quantum backaction, caused by microwave shot noise, below the backaction arising in a continuous position monitoring. By perturbing the measurement slightly (i.e., reservoir engineering), such measurements could be used to generate stabilized entanglement between two macroscopic mechanical oscillators. This prepares a canonical entangled state known as the two-mode squeezed state. It corresponds to the variances of collective position and momentum quadratures being reduced below the quantum zero-point fluctuations level. We carry out such a measurements, and infer the existence of entanglement in the steady state by combining measurements of correlated mechanical fluctuations with an analysis of the microwaves emitted from the cavity.
Bio: Prof. Mika A. Sillanpää obtained his Ph.D. Helsinki University of Technology, Finland in 2005. Prof. Sillanpää spent years 2005-2007 as a postdoctoral researcher at NIST in Boulder, Colorado, USA, studying superconducting quantum bits made of Josephson junctions. Starting 2010, he established the Quantum Nanomechanics research team at the Aalto University, Helsinki, Finland. In 2012 he was nominated as a tenure-track associate professor at the Department of Applied Physics. He obtained a tenured professorship in 2015. Prof. Sillanpää’s research is recently focused on quantum phenomena in micromechanical and cavity optomechanical systems. He has published six original research papers in either Nature or Science. He has been awarded twice the prestigious frontier research funding from the European Research Council; the Starting Grant in 2009, and the Consolidator Grant in 2013. He is a member of the Finnish Academy of Science and Letters since 2016, recipient of the Väisälaä Award by the Finnish Academy of Science and Letters, and a recipient of the IUPAP Young Scientist Prize.