Seminar Prof. Dr. Roman Schnabel

Title: From interferometers using squeezed states of light to the generation of microscopic Schrödinger cat states.

In this talk, four types of experiments are presented in which continuous wave laser interferometers were combined with squeezing of the quantum uncertainty of light. First, a brief overview of the success story of squeezed light in gravitational wave detectors will be given. Our recent experiment improved the detection of the vibrational frequencies of a surface by suppressing the photon noise by 10 dB, even though the surface is highly absorbing. In another experiment, we measured the ensemble trajectory of the complex amplitude of an optical signal much more accurately than the Heisenberg uncertainty principle seems to allow. Finally, I present an experiment in which an ensemble of a squeezed vacuum state of light was converted into a superposition of two coherent states with a phase difference of 180° using a superconducting nanowire single photon detector. The latter state is usually understood as a microscopic Schrödinger cat state.

Biography
Roman Schnabel received his doctorate in 1999 and was a Feodor-Lynen Research Fellow at the Australian National University, where he worked on quantum teleportation. From 2003 to 2014, he was professor at Leibniz Universität Hannover and pioneered the squeezed light technology, which is now used in GEO600, LIGO and Virgo. Since 2014, he has been working at the University of Hamburg, at the Institute of Quantum Physics. He is co-founder of Noisy-Labs GmbH, member of the LIGO Scientific Collaboration (LSC) and the Academy of Sciences in Hamburg. His awards and honors include the APS 2013 Joseph F. Keithley Award.