The 2nd International Symposium on Nonlinear Dynamics 
 27-30 Oct., 2007, Shanghai, China

Special Plenary Lecture

Mechanical quantum resonators: A proposal to create and detect single phonons in a bulk mechanical resonator

Andrew N. Cleland
Professor of Physics
University of California
Santa Barbara CA 93106
http://www.iqcd.ucsb.edu/clelandgroup/

We are engaged in a project to investigate mechanical resonators in the low-temperature, single-phonon quantum regime. We are coupling the highly nonlinear inductance of a Josephson phase qubit with a microwave frequency, bulk mechanical resonator, to enable us to demonstrate the coherent creation and manipulation of single phonons in the resonating element. The mechanical system is a novel type of high quality factor, GHz frequency piezoelectric resonator, which can have unprecedented quality factor in this frequency band. The quantum mechanical properties of the resonators, especially in the single-phonon regime, will be probed by Josephson junction circuits recently developed for applications to superconducting quantum computation. This experiment should reveal values for the T1 relaxation time and the T2 coherence time for the resonator, in the single phonon limit. It should also allow us to demonstrate "quantum refrigeration", removing individual phonons from a resonator with multi-phonon occupation, and demonstrate nanoelectromechanical Rabi oscillations. This would comprise the first demonstration of quantum mechanics in a macroscopic mechanical system, and would provide a milestone in quantum physics.

Representative publications:

"Quantum mechanics of a macroscopic variable: The phase difference of a Josephson junction." J. Clarke, A.N. Cleland, M. Devoret, D. Esteve, J. Martinis, Science 239, 992 (1988).

"Nanostructure-based mechanical electrometry." A.N. Cleland and M.L. Roukes, Nature 392, 160 (1998).

"Nanometre-scale displacement sensing using a single-electron transistor." R.G. Knobel and A.N. Cleland. Nature 424, 291 (2003).

"Carbon nanotubes tune up (News & Views)." A.N. Cleland. Nature 431, 251 (2004).

"Measurement of the entanglement of two superconducting qubits via state tomography." M. Steffen, M. Ansmann, R.C. Bialczak, N. Katz, E. Lucero, R. McDermott, M. Neeley, E.M. Weig, A.N. Cleland, J.M. Martinis. Science 313, 1423-1425 (2006).

"Coherent State Evolution in a Superconducting Qubit from Partial-Collapse Measurement." N. Katz, M. Ansmann, R.C. Bialczak, E. Lucero, R. McDermott, M. Neeley, M. Steffen, E.M. Weig, A.N. Cleland, J.M. Martinis, and A.N. Korotkov. Science 312, 1498-1500 (2006).

Book: Foundations of Nanomechanics. A.N. Cleland. Springer-Verlag (2002).