Mode expansion and Bragg filtering enable a high-fidelity fiber-based photon-pair source

We report the development of a fiber-based single spatial mode source of photon-pairs where the efficiency of extracting photon-pairs is improved over a previous source [18] through the use of fiber-end expansion and Bragg filters. This improvement in efficiency enabled a spectrally bright and pure photon-pair source having a small second-order correlation function (0.03) and a raw spectral brightness of 44,700 pairs/(s nm mW). The source can be configured to generate entangled photon-pairs,characterized via optimal and minimal quantum state tomography, to have a fidelity of 97% and tangle of 92%, without subtracting any background.Comment: Manuscript was edited to provide additional information on the end-tapered photonic crystal fibers and high efficiency volume Bragg gratings. The analysis of the extraction efficiency was also expanded, and experimental uncertainties included where relevant. This paper has been accepted for publication in Optics Expres

Experimental study on a dual compensation chamber loop heat pipe with dual bayonet tubes

Dual compensation chamber loop heat pipe (DCCLHP) holds great application potential in the future aircraft thermal management. In this work, a DCCLHP with dual bayonet tubes was first proposed and fabricated, aiming to improve its startup performance especially at small heat loads in the terrestrial surroundings. Extensive experimental validation was conducted at three typical attitudes of the evaporator/CCs, i.e., the vertical attitude, 45° tilt angle and the horizontal attitude, mainly focusing on its startup characteristics and heat transport capability. According to the experimental results, the DCCLHP with dual bayonet tubes can successfully realize the startup at small heat loads in whatever attitudes of the evaporator/CCs in the ground condition, and reach a heat transport limit greater than 400 W over a distance of 2.0 m. No obvious operating instability was observed in the DCCLHP operation. In addition, a new flow mechanism was observed in the experiment, i.e., a local natural circulation of the working fluid driven by gravity occurred in the loop composed of the evaporator, the CCs, the bayonet tubes, and the branches of the liquid line. This local circulation of working fluid was identified to appear only when the evaporator/CCs were at a certain tilt angle and the heat loads were relatively small