分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the most
sensitive radio telescope for pulsar observations. We make polarimetric
measurements of a large number of faint and distant pulsars using the FAST. We
present the new measurements of Faraday rotation for 134 faint pulsars in the
Galactic halo. Significant improvements are also made for some basic pulsar
parameters for 15 of them. We analyse the newly determined rotation measures
(RMs) for the Galactic magnetic fields by using these 134 halo pulsars,
together with previously available RMs for pulsars and extragalactic radio
sources and also the newly determined RMs for another 311 faint pulsars which
are either newly discovered in the project of the Galactic Plane Pulsar
Snapshot (GPPS) survey or previously known pulsars without RMs. The RM
tomographic analysis in the first Galactic quadrant gives roughly the same
field strength of around 2~$\mu$G for the large-scale toroidal halo magnetic
fields. The scale height of the halo magnetic fields is found to be at least
2.7$\pm$0.3~kpc. The RM differentiation of a large number of pulsars in the
Galactic disk in the Galactic longitude range of $26^{\circ}
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the most
sensitive radio telescope for pulsar observations. We make polarimetric
measurements of a large number of faint and distant pulsars using the FAST. We
present the new measurements of Faraday rotation for 134 faint pulsars in the
Galactic halo. Significant improvements are also made for some basic pulsar
parameters for 15 of them. We analyse the newly determined rotation measures
(RMs) for the Galactic magnetic fields by using these 134 halo pulsars,
together with previously available RMs for pulsars and extragalactic radio
sources and also the newly determined RMs for another 311 faint pulsars which
are either newly discovered in the project of the Galactic Plane Pulsar
Snapshot (GPPS) survey or previously known pulsars without RMs. The RM
tomographic analysis in the first Galactic quadrant gives roughly the same
field strength of around 2~$\mu$G for the large-scale toroidal halo magnetic
fields. The scale height of the halo magnetic fields is found to be at least
2.7$\pm$0.3~kpc. The RM differentiation of a large number of pulsars in the
Galactic disk in the Galactic longitude range of $26^{\circ}
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Mengqi Wang
Haoyu Sun
Xiangyu Ye
Pei Yu
Hangyu Liu
Jingwei Zhou
Pengfei Wang
Fazhan Shi
Ya Wang
Jiangfeng Du
摘要： To efficiently align the creation of defect center with photonics structure in nanoscale precision is one of the outstanding challenges for realizing high-performance photonic devices and the application in quantum technology such as quantum sensing, scalable quantum systems, and quantum computing network. Here, we propose a facile self-aligned patterning technique wholly based on conventional engineering technology, with the doping precision can reach ~15nm. Specifically, we demonstrate this technique by fabricating diamond nanopillar sensor arrays, which show high consistency and near-optimal photon counts, high yield approaching the theoretical limit, and high filtering efficiency for different NV centers. Combined with appropriate crystal orientation, a saturated fluorescence rate of 4.65 Mcps and the best reported fluorescence-dependent detection sensitivity of 1900 cps^(-1/2) are achieved. This technique applicable to all similar solid-state systems should facilitate the development of parallel quantum sensing and scalable information processing.
分类： 物理学 >> 电磁学、光学、声学、传热、经典力学和流体动力学 分类： 材料科学 >> 纳米科学和纳米技术 提交时间： 2017-02-23
摘要： The hexagonal boron nitride (h-BN) nanosheets are synthesized by the liquid-phase exfoliation method and transferred onto the microfiber by optical deposition method. The h-BN-deposited microfiber exhibits dual-function, that is, saturable absorption and high-nonlinearity. To check the laser performance by using the proposed h-BN device, it is inserted into an erbium-doped fiber laser (EDFL). In experiment, we demonstrate a tunable, switchable dual-wavelength soliton pulse by properly adjusting the pump power and the polarization state in the EDFL. The dual-wavelength soliton laser has a pump threshold of 50 mW at 976 nm, pulse energy of up to 3.4 nJ, peak power of about 2.62 kW, and pulse duration of about 1.3 ps. Additionally, we also demonstrate switchable operation of single-wavelength soliton pulse located at 1531.5 and 1557.5 nm, respectively. Our finding unambiguously implies that apart from its fantastic electric and thermal property, h-BN nanosheets may also possess attractive optoelectronic property for nonlinear photonics, such as mode-locker, Q-switcher, optical limiter and so on.
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