We have cooled a macroscopic LC electrical resonator using feedback-cooling combined with an ultrasensitive dc Superconducting Quantum Interference Device (SQUID) current amplifier. The resonator, with resonance frequency of 11.5 kHz and bath temperature of 135 mK, is operated in the high coupling limit so that the SQUID back-action noise overcomes the intrinsic resonator thermal noise. The effect of correlations between the amplifier noise sources clearly show up in the experimental data, as well as the interplay of the amplifier noise with the resonator thermal noise. The lowest temperature achieved by feedback is 14 mu K, corresponding to 26 resonator photons, and approaches the limit imposed by the noise energy of the SQUID amplifier. Copyright (C) EPLA, 2010
Active cooling of an audio-frequency electrical resonator to microkelvin temperatures / Vinante, A.; Bonaldi, M.; Mezzena, R.; Falferi, P.. - In: EUROPHYSICS LETTERS. - ISSN 1286-4854. - 92:3(2010), p. 34005. [10.1209/0295-5075/92/34005]
Active cooling of an audio-frequency electrical resonator to microkelvin temperatures
Vinante A.;Mezzena R.;
2010-01-01
Abstract
We have cooled a macroscopic LC electrical resonator using feedback-cooling combined with an ultrasensitive dc Superconducting Quantum Interference Device (SQUID) current amplifier. The resonator, with resonance frequency of 11.5 kHz and bath temperature of 135 mK, is operated in the high coupling limit so that the SQUID back-action noise overcomes the intrinsic resonator thermal noise. The effect of correlations between the amplifier noise sources clearly show up in the experimental data, as well as the interplay of the amplifier noise with the resonator thermal noise. The lowest temperature achieved by feedback is 14 mu K, corresponding to 26 resonator photons, and approaches the limit imposed by the noise energy of the SQUID amplifier. Copyright (C) EPLA, 2010I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione
