The nitrogen-vacancy defect center (N-V center) is a promising candidate for quantum information processing due to the possibility of coherent manipulation of individual spins in the absence of the cryogenic requirement. We report a room-temperature implementation of the Deutsch-Jozsa algorithm by encoding both a qubit and an auxiliary state in the electron spin of a single N-V center. By thus exploiting the specific S=1 character of the spin system, we demonstrate how even scarce quantum resources can be used for test-bed experiments on the way towards a large-scale quantum computing architecture.

A crucial challenge for future quantum technologies is to protect fragile entanglement against environment-induced decoherence. Here we demonstrate experimentally that dynamical decoupling can preserve bipartite pseudoentanglement in phosphorous donors in a silicon system. In particular, the lifetime of pseudoentangled states is extended from 0.4  μs in the absence of decoherence control to 30  μs in the presence of a two-flip dynamical decoupling sequence.

Fabrication of quasi-three-dimensional micro/nanomechanical components using electron beam cross-linked poly (methyl methacrylate) resist J.Novel scanning near-field optical microscopy/atomic force microscope probes by combined micromachining and electron-beam nanolithographyThe combination of direct-write electron beam lithography and bulk silicon micromachining is shown to give great flexibility in the definition of nanosensors. The technique is based on a novel method for coating the specimen with electron beam resist allowing high resolution features to be defined on the top of micromachined asperities or in 200 m deep etched holes. Examples of sensors fabricated using this method include advanced magnetic nanosensors such as Hall probe sensors, electromagnetic coils or combined coils and Hall probes. Near-field optical atomic force microscope probes are demonstrated with reproducible aperture size down to 20ϫ35 nm. Near-field optical probes using a shaped aperture to allow the passage of linearly polarized light are shown to offer optical throughputs up to 2% with modest collection optics. The use of a near-field optical probe having a crossed slit form is demonstrated to give high throughput and resolution in two dimensions for the imaging of fluorescent objects. Near-field optical probes with multiple apertures of closely matched size are demonstrated.

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A facile hydrothermal route at designated pH values has been developed to synthesize a series of welldispersed LaF 3 colloidal nanocrystals (NCs) with a rich variety of morphologies, including nanoparticles, hexagonal nanoplates and fullerene-like nanoparticles. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy were used to characterize the samples. It is found that the formation of monodispersed fluoride NCs not only closely correlates with the pH values of the mother solutions, but also depends on the basicity of the base employed to adjust the pH value. The strong alkaline solution in the absence of any organic additive in this system was found to be a prerequisite for producing hexagonal fullerene-like LaF 3 nanodisks. A mechanism for the formation of the fullerene-like LaF 3 via the local Ostwald ripening process has been proposed based on observations of time-dependent experiments. The multicolor upconversion (UC) emission was successfully realized in a series of Yb 3+ /Er 3+ doped LaF 3 NCs by excitation in the near-infrared region. The UC emission ratios of red to green for a series of LaF 3 NCs can be tuned by adjusting the pH values of the mother liquids, and an UC mechanism activated by high-energy phonons inherent in the hollow LaF 3 nanoplates is proposed. It is expected that these rare-earth fluoride NCs might have potential applications in photocatalysis, biolabelling and drug-delivery.