1,977 research outputs found

    High-sensitivity optical measurement of mechanical Brownian motion

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    We describe an experiment in which a laser beam is sent into a high-finesse optical cavity with a mirror coated on a mechanical resonator. We show that the reflected light is very sensitive to small mirror displacements. We have observed the Brownian motion of the resonator with a very high sensitivity.Comment: 4 pages, 4 figures, RevTe

    Quantum engineering of squeezed states for quantum communication and metrology

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    We report the experimental realization of squeezed quantum states of light, tailored for new applications in quantum communication and metrology. Squeezed states in a broad Fourier frequency band down to 1 Hz has been observed for the first time. Nonclassical properties of light in such a low frequency band is required for high efficiency quantum information storage in electromagnetically induced transparency (EIT) media. The states observed also cover the frequency band of ultra-high precision laser interferometers for gravitational wave detection and can be used to reach the regime of quantum non-demolition interferometry. And furthermore, they cover the frequencies of motions of heavily macroscopic objects and might therefore support the attempts to observe entanglement in our macroscopic world.Comment: 12 pages, 3 figure

    Squeezing and entangling nuclear spins in helium 3

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    We present a realistic model for transferring the squeezing or the entanglement of optical field modes to the collective ground state nuclear spin of 3^3He using metastability exchange collisions. We discuss in detail the requirements for obtaining good quantum state transfer efficiency and study the possibility to readout the nuclear spin state optically

    Self-cooling of a movable mirror to the ground state using radiation pressure

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    We show that one can cool a micro-mechanical oscillator to its quantum ground state using radiation pressure in an appropriately detuned cavity (self-cooling). From a simple theory based on Heisenberg-Langevin equations we find that optimal self-cooling occurs in the good cavity regime, when the cavity bandwidth is smaller than the mechanical frequency, but still larger than the effective mechanical damping. In this case the intracavity field and the vibrational mechanical mode coherently exchange their fluctuations. We also present dynamical calculations which show how to access the mirror final temperature from the fluctuations of the field reflected by the cavity.Comment: 4 pages, 3 figure

    Stationary entanglement between two movable mirrors in a classically driven Fabry-Perot cavity

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    We consider a Fabry-Perot cavity made by two moving mirrors and driven by an intense classical laser field. We show that stationary entanglement between two vibrational modes of the mirrors, with effective mass of the order of micrograms, can be generated by means of radiation pressure. The resulting entanglement is however quite fragile with respect to temperature.Comment: 15 pages, 3 figure

    High-sensitivity optical monitoring of a micro-mechanical resonator with a quantum-limited optomechanical sensor

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    We experimentally demonstrate the high-sensitivity optical monitoring of a micro-mechanical resonator and its cooling by active control. Coating a low-loss mirror upon the resonator, we have built an optomechanical sensor based on a very high-finesse cavity (30000). We have measured the thermal noise of the resonator with a quantum-limited sensitivity at the 10^-19 m/rootHz level, and cooled the resonator down to 5K by a cold-damping technique. Applications of our setup range from quantum optics experiments to the experimental demonstration of the quantum ground state of a macroscopic mechanical resonator.Comment: 4 pages, 5 figure

    A micropillar for cavity optomechanics

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    We present a new micromechanical resonator designed for cavity optomechanics. We have used a micropillar geometry to obtain a high-frequency mechanical resonance with a low effective mass and a very high quality factor. We have coated a 60-ÎĽ\mum diameter low-loss dielectric mirror on top of the pillar and are planning to use this micromirror as part of a high-finesse Fabry-Perot cavity, to laser cool the resonator down to its quantum ground state and to monitor its quantum position fluctuations by quantum-limited optical interferometry

    Long-lived quantum memory with nuclear atomic spins

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    We propose to store non-classical states of light into the macroscopic collective nuclear spin (101810^{18} atoms) of a 3^3He vapor, using metastability exchange collisions. These collisions, commonly used to transfer orientation from the metastable state 23S_12^{3}S\_1 to the ground state state of 3^3He, can also transfer quantum correlations. This gives a possible experimental scheme to map a squeezed vacuum field state onto a nuclear spin state with very long storage times (hours).Comment: 4 page

    Seeking Sustainability: COSA preliminary analysis of sustainability initiatives in the coffee sector

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    The growing economic value and consumer popularity of sustainability standards inevitably raise questions about the extent to which their structure and dynamics actually address many environmental, economic and public welfare issues. The Committee on Sustainable Assessment (COSA) was formed, in part, to develop a scientifically credible framework capable of assessing the impacts associated with the adoption of sustainability initiatives. This paper examines the pilot phase of vetting and testing the COSA method, an innovative management tool used to gather and analyze data using economic, environmental and social metrics.sustainability initiatives, standards, organic, fair trade, Rainforest, social, environmental, economic certification

    The influence of philosophical perspectives in integrative research: a conservation case study in the Cairngorms National Park

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    The benefits of increasing the contribution of the social sciences in the fields of environmental and conservation science disciplines are increasingly recognized. However, integration between the social and natural sciences has been limited, in part because of the barrier caused by major philosophical differences in the perspectives between these research areas. This paper aims to contribute to more effective interdisciplinary integration by explaining some of the philosophical views underpinning social research and how these views influence research methods and outcomes. We use a project investigating the motivation of volunteers working in an adaptive co-management project to eradicate American Mink from the Cairngorms National Park in Scotland as a case study to illustrate the impact of philosophical perspectives on research. Consideration of different perspectives promoted explicit reflection of the contributing researcher's assumptions, and the implications of his or her perspectives on the outcomes of the research. We suggest a framework to assist conservation research projects by: (1) assisting formulation of research questions; (2) focusing dialogue between managers and researchers, making underlying worldviews explicit; and (3) helping researchers and managers improve longer-term strategies by helping identify overall goals and objectives and by identifying immediate research needs
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