Quantum electromechanical systems

Quantum electromechanical systems are nano-to-micrometer (micron) scale mechanical resonators coupled to electronic devices of comparable dimensions, such that the mechanical resonator behaves in a manifestly quantum manner. We review progress towards realising quantum electromechanical systems, beginning with the phononic quantum of thermal conductance for suspended dielectric wires. We then describe efforts to reach the quantum zero-point displacement uncertainty detection limit for (sub)micron-scale mechanical resonators using the single electron transistor as displacement transducer. A scheme employing the Cooper-pair box as coherent control device to generate and detect quantum superpositions of distinct position states is then described. Finally, we outline several possible schemes to demonstrate various other quantum effects in (sub)micron mechanical resonators, including single phonon detection, quantum squeezed states and quantum tunnelling of mechanical degrees of freedom. (C) 2003 Elsevier B.V. All rights reserved.