Classical Pendulum Feels Quantum Back-Action

In this thesis, ultimate sensitive measurement for weak force imposed on a suspended mirror is performed with the help of a laser and an optical cavity for the development of gravitational-wave detectors. According to the Heisenberg uncertainty principle, such measurements are subject to a fundamental noise called quantum noise, which arises from the quantum nature of a probe (light) and a measured object (mirror). One of the sources of quantum noise is the quantum back-action, which arises from the vacuum fluctuation of the light. It sways the mirror via the momentum transferred to the mirror upon its reflection for the measurement. The author discusses a fundamental trade-off between sensitivity and stability in the macroscopic system, and suggests using a triangular cavity that can avoid this trade-off. The development of an optical triangular cavity is described and its characterization of the optomechanical effect in the triangular cavity is demonstrated. As a result, for the first time in the world the quantum back-action imposed on the 5-mg suspended mirror is significantly evaluated. This work contributes to overcoming the standard quantum limit in the future.

Nominated as an outstanding contribution by The University of Tokyo's Physics Department in 2014 Describes precise force measurement imposed on a suspended mirror and the effect of the quantum back-action Introduces a newly developed technique on how to trap the macroscopic mirror by laser, free from the thermal bath Includes supplementary material: sn.pub/extras

Autorentext

Dr.Nobuyuki Matsumoto
The university of Tokyo, Physics Department
matsumoto@granite.phys.s.u-tokyo.ac.jp

Inhalt
Introduction.- Theory of Optomechanics.- Application of Optomechanics.- Optical Torsional Spring.- Experimental Setup.- Experimental Results.- The Future.- Conclusions.