Quantum nondemolition measurement of Fock states of mesoscopic mechanical oscillators

We investigate a scheme that makes a quantum nondemolition (QND) measurement of the excitation level of a mesoscopic mechanical oscillator by utilizing the anharmonic coupling between two beam bending modes. The nonlinear coupling between the two modes shifts the resonant frequency of the readout oscillator in proportion to the excitation level of the system oscillator. This frequency shift may be detected as a phase shift of the readout oscillation when driven on resonance. We derive an equation for the reduced density matrix of the system oscillator, and use this to study the conditions under which discrete jumps in the excitation level occur. The appearance of jumps in the actual quantity measured is also studied using the method of quantum trajectories. We consider the feasibility of the scheme for experimentally accessible parameters.

Ion trap transducers for quantum electromechanical oscillators

An enduring challenge for contemporary physics is to experimentally observe and control quantum behavior in macroscopic systems. We show that a single trapped atomic ion could be used to probe the quantum nature of a mesoscopic mechanical oscillator precooled to 4 K, and furthermore, to cool the oscillator with high efficiency to its quantum ground state. The proposed experiment could be performed using currently available technology.

Molecular motors-based micro- and nano-biocomputation devices

Protein molecular motors, which are natural nano-machines that convert the chemical energy into mechanical work for cellular motion, muscle contraction and cell division, have been integrated in the last decade in primitive nanodevices based on the motility of nano-biological objects in micro- and nano-fabricated structures. However, the motility of microorganisms powered by molecular motors has not been similarly exploited. Moreover, among the proposed devices based on molecular motors, i.e., nanosensors, nano-mechanical devices and nano-imaging devices, biocomputation devices are conspicuously missing. The present contribution discusses, based on the present state of the art nano- and micro-fabrication, the comparative advantages and disadvantages of using nano- and micro-biological objects in future computation devices. (c) 2006 Elsevier B.V. All rights reserved.

Effect of microstructure on material removal mechanisms in nano/micro grinding of tungsten carbide mould inserts

Nano/micro grinding of tungsten carbide (WC) mould inserts was performed. A form accuracy of 〜200nm (in PV) and a surface roughness of 〜7nm were achieved. Nanoindentation revealed that small chipping or cracking occurred even at a penetration depth of 38nm, which could hinder the further improvement of surface quality during grinding. It was found that when grinding was conducted at nanometric scale, the microstructure of the work material and the morphology of the WC grains should be taken into account to enable a fully ductile removal. Copyright 2005 by the Japan Society of Mechanical Engineers