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High-quality frequency references are the cornerstones in position, navigation and timing applications of both scientific and commercial domains. Optomechanical oscillators, with direct coupling to continuous-wave light and non-material-limited f × Q product, are long regarded as a potential platform for frequency reference in radio-frequency-photonic architectures. However, one major challenge is the compatibility with standard CMOS fabrication processes while maintaining optomechanical high quality performance. Here we demonstrate the monolithic integration of photonic crystal optomechanical oscillators and on-chip high speed Ge detectors based on the silicon CMOS platform. With the generation of both high harmonics (up to 59th order) and subharmonics (down to 1/4), our chipset provides multiple frequency tones for applications in both frequency multipliers and dividers. The phase noise is measured down to −125 dBc/Hz at 10 kHz offset at ~400 μW dropped-in powers, one of the lowest noise optomechanical oscillators to date and in room-temperature and atmospheric non-vacuum operating conditions. These characteristics enable optomechanical oscillators as a frequency reference platform for radio-frequency-photonic information processing.

By combining the UV spectra from IUE with photometric data in the optical band, we present a quantitative study on the continuum energy distributions of LBVs to determine the structure and geometry of LBV winds. It is shown that the shape of continuum energy distributions around the Balmer jump is sensitive to the velocity law of LBV winds. A simple, spherically symmetric wind model including free-bound and free-free radiation is constructed to compute the continuum energy distributions of LBVs. By matching theoretical ones to the observed continuum energy distributions around the Balmer jump, we have obtained value of the exponent of the velocity law in both minimum and maximum state for five LBVs, i.e., AG Car, HR Car, R40, S Dor, and R127. We have found that is about 0.5Y0.7 in the minimum state and larger than 1.5 in the maximum state. Transitions in the ionization states of metals between the minimum and maximum state of LBVs, which lead to changes in the radiative acceleration due to spectral lines, are most likely responsible for such effect on the velocity law. We have also determined the geometry of the wind and found that a spherically symmetric wind model can well reproduce the observed continuum energy distributions of the five LBVs. Based on these results we suggest that the wind of LBVs be basically quasi-spherical, maybe with some clumpy structure in the spherical wind to produce some observed aspherical features.

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Abstract. The continuum energy distributions of R127 and R110 in the outburst phase are fitted by use of a optically envelope model. Both stars show two peaks in the continuum energy distributions in which one lies in the short-wavelength range (near 1250Å) and the other in the optical band. We suggest that the fluxes in the UV and optical bands may have different origins: the UV flux comes from the central star and the optical flux comes from the expanded optically envelope. We construct such a model for LBVs with the use of two LTE atmosphere models with different temperatures, and find it to be in satisfactory agreement with the observed spectral energy distributions of R127 and R110.

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We describe a scalable optomechanical array, with double-disk resonators, for two-qubit quantum phase gate of phonon states where mechanical systems exhibit significantly long lifetime. Simulation results show high fidelity and low photon loss.OCIS Code: (270.5585) Quantum information and processing; (220.4880) Optomechanics IntroductionTwo qubit controlled phase gate and one-qubit gate are universal for constructing quantum computer [1]. In order to implement quantum computer into a real physical system, a quantum system is needed. Optomechanical systems have several advantages in comparison to the all-photonic physical systems, primarily related to the attainable lifetime of the mechanical states [2-4]. Here we focus on a specific mesoscopic optomechanical system which combines the large per photon optical gradient force with the sensitive feedback of a high quality factor whispering-gallery microcavity [5,6] and utilize the coupling between two mechanical modes to generate a quantum phase gate between phonon states. Theory and numerical simulationsThe structure consists of a pair of silica disks separated by a nanoscale gap which shows extremely strong dynamical backaction, orders of magnitude larger than in other optomechanical systems [5]. We consider an optomechanical scheme consisting of an array of double-disk resonators, all coupled to a common optical bus waveguide (as shown in Fig. 1). Each element of the array contains a cavity mode a and two mechanical modes: differential flapping mode b and common breathing mode c. Energy level structure of simplified system for one element is shown in Fig. 2. The optomechanical coupling is om g and the internal mechanical coupling is mm g . Omitting the terms which concern the Langevin noises, we can easily obtain Heisenberg equations of motion [7]. Our scheme operates in the weak excitation limit, so that the motion equations can be solved, with the transport relation ( )