Abstract
We apply a feedback cooling technique to simultaneously cool the three electromechanical normal modes of the ton-scale resonant-bar gravitational wave detector AURIGA. The measuring system is based on a dc superconducting quantum interference device (SQUID) amplifier, and the feedback cooling is applied electronically to the input circuit of the SQUID. Starting from a bath temperature of 4.2 K, we achieve a minimum temperature of 0.17 mK for the coolest normal mode. The same technique, implemented in a dedicated experiment at subkelvin bath temperature and with a quantum limited SQUID, could allow to approach the quantum ground state of a kilogram-scale mechanical resonator.
- Received 3 March 2008
DOI:https://doi.org/10.1103/PhysRevLett.101.033601
©2008 American Physical Society
Viewpoint
How to silence a one-ton bell
Published 14 July 2008
The longitudinal ringing mode of a metal bar resonator weighing approximately one metric ton has been cooled to submillikelvin temperatures with the use of active amplifier feedback. Further improvements may allow researchers to approach the quantum limit for cooling macroscopic objects.
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