Nanoparticles with masses of 106 - 109 a.m.u are bridges between the macroscopic and the microscopic world; they link classical and quantum mechanics. The question of their gravity induced decoherence is a hot topic in literature [1]. These particles are also very suitable to test masses to probe ultra-weak external forces.
Our goal is to trap one nanoparticle in an optical tweezer and to manipulate their centre of mass motion in particular by optical forces, thanks to the polarizability of these objects. Silica nanospheres are particularly interesting as their centre of mass motion is strongly decoupled from internal degrees of freedom (heating !): They can be cooled down to a few mKelvin [2,3]. This efficient cooling allows forces to be probed down to zeptoNewton (1021 N !) strength.
This project is led by Matthias Büchner.
Literature :
[1] On Gravity’s role in Quantum State Reduction,
R. Penrose, Gen. Rev. Grav. 28, 581 (1996)
[2] Millikelvin cooling of an optically trapped microsphere in vacuum,
T. Li, S. Kheifets, M. Raizen, Nat. Physics 7, 527-530 (2011)
[3] Subkelvin Parametric Feedback Cooling of a Laser-Trapped Nanoparticle,
J. Gieseler, B. Deutsch, R. Quidant, L. Novotny, Phys. Rev. Let. 109, 103603 (2012)