Hannover 2010 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 50: Micromechanical Oscillators I

Q 50.2: Talk

Thursday, March 11, 2010, 15:30–15:45, A 320

Cooling of nanomechanical resonator via coupling to flux qubits — •Keyu Xia and Jörg Evers — Max-Planck-Institut für Kernphysik, Heidelberg, Germany

In recent years, the idea of observing quantum phenomena in macroscopic objects raised considerable effort to achieve the mechanical ground state of a micro- or nanomechanical resonator (NAMR). One obstacle is that ground state cooling in most schemes can only be achieved in the so-called resolved or strong-confinement regime [1].

Here, we discuss cooling of a NAMR to its ground state in the weak-confinement regime by coupling it to flux qubits. Our first approach [2] is based on electromagnetically induced transparency (EIT) cooling which was already successfully proposed and implemented for trapped ions [3]. EIT cooling relies on favorable modification of the cooling field absorption spectrum by quantum interference. We show that our scheme has several advantages over previously known cooling mechanisms for NAMRs. Our second approach [4] does not have a straightforward analogy in trapped atoms in ions. It is based on the coupling of two interacting flux qubits to a single NAMR. We demonstrate that collective effects lead to an efficient ground state cooling of the NAMR in the weak-confinement regime.

[1] F. Elste et al., Phys. Rev. Lett., 102, 207209 (2009)

[2] K. Xia and J. Evers, Phys. Rev. Lett. 103, 227203 (2009)

[3] G. Morigi et al., Phys. Rev. Lett. 85, 4458 (2000); F. Schmidt-Kaler et al., Appl. Phys. B 73, 807 (2001)

[4] K. Xia and J. Evers, arXiv:0912.1990[quant-ph]