Feedback cooling of the normal modes of a massive electromechanical system to submillikelvin temperature.
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.
Vinante
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Istituto di Fotonica e Nanotecnologie, CNR-Fondazione Bruno Kessler, 38100 Povo, Trento, Italy. vinante@science.unitn.it
Bignotto
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M
Bonaldi
M
M
Cerdonio
M
M
Conti
L
L
Falferi
P
P
Liguori
N
N
Longo
S
S
Mezzena
R
R
Ortolan
A
A
Prodi
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GA
Salemi
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F
Taffarello
L
L
Vedovato
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G
Vitale
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Zendri
J-P
JP