We measure the motion of an ultrasoft cantilever, carrying a ferromagnetic particle, by means of a superconducting quantum interference device (SQUID). In our scheme, the cantilever motion modulates the magnetic flux in the SQUID due to the coupling with the magnetic particle. For the cantilever fundamental mode, cooled to temperatures below 100 mK, we achieve a dimensionless coupling factor as large as 0.07, displacement sensitivity of 200 fm/Hz⎯⎯⎯⎯⎯√ , and subattonewton force sensitivity. We demonstrate the outstanding combination of very low displacement and force noise by feedback-cooling the cantilever mode to an effective mode temperature of 160 𝜇K . We thank G. Koning, D. van der Zalm, and R. Koehler for technical support. We acknowledge support from the European Microkelvin Collaboration, in particular for the development of the SQUID sensor. Further financial support was provided by an ERC Starting Grant and by FOM.
High sensitivity SQUID-detection and feedback-cooling of an ultrasoft microcantilever
Vinante, Andrea;
2012-01-01
Abstract
We measure the motion of an ultrasoft cantilever, carrying a ferromagnetic particle, by means of a superconducting quantum interference device (SQUID). In our scheme, the cantilever motion modulates the magnetic flux in the SQUID due to the coupling with the magnetic particle. For the cantilever fundamental mode, cooled to temperatures below 100 mK, we achieve a dimensionless coupling factor as large as 0.07, displacement sensitivity of 200 fm/Hz⎯⎯⎯⎯⎯√ , and subattonewton force sensitivity. We demonstrate the outstanding combination of very low displacement and force noise by feedback-cooling the cantilever mode to an effective mode temperature of 160 𝜇K . We thank G. Koning, D. van der Zalm, and R. Koehler for technical support. We acknowledge support from the European Microkelvin Collaboration, in particular for the development of the SQUID sensor. Further financial support was provided by an ERC Starting Grant and by FOM.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
