Abstract

Entanglement, “the characteristic trait of quantum mechanics” [1], has raised widespread interest in different branches of physics. It provides insight into the fundamental structure of physical reality and it has become a basic resource for many quantum information processing schemes. So far entanglement has been experimentally prepared and manipulated using microscopic quantum systems such as photons, atoms and ions. Nothing in the principles of quantum mechanics prevents macroscopic systems to attain entanglement. However, the answer to the question as to what extent entanglement should hold when going towards “classical” systems is yet unknown. Therefore it is of crucial importance to investigate the possibilities to obtain entangled states of macroscopic systems [2] and to study the robustness of entanglement against temperature. Experiments in this direction include single-particle interference of macro-molecules [3], the demonstration of entanglement between collective spins of atomic ensembles [4], and of entanglement in Josephson-junction qubits [5]. Mechanical oscillators are of particular interest since they resemble a prototype of “classical” systems. Thanks to the fast-developing field of microfabrication, micro-or nano-mechanical oscillators can now be prepared and controlled to a very high precision [6]. In addition, several theoretical proposals exist that suggest how to reach the quantum regime for such systems [7]. Experimentally, quantum limited measurements have been developed that could allow ground state detection [8]. However, quantum effects in mechanical oscillators have not been demonstrated to date.

© 2007 IEEE