Polarization mode dispersion in radio-frequency interferometric embedded fiber-optic sensors

The effect of fiber birefringence on the propagation delay in an embedded fiber-optic strain sensor is studied. The polarization characteristics of the sensor are described in terms of polarization mode dispersion through the principal states of polarization and their differential group delay. Using these descriptors, an analytical expression for the response of the sensor for an arbitrary input state of polarization is given and experimentally verified. It is found that the differential group delay, as well as the input and output principal states of polarization, vary when the embedded fiber is strained, leading to fluctuations in the sensor output. The use of high birefringence fibers and different embedding geometries is examined as a means for reducing the polarization dependency of the sensor

Single-photon emitting diode in silicon carbide

Electrically driven single-photon emitting devices have immediate applications in quantum cryptography, quantum computation and single-photon metrology. Mature device fabrication protocols and the recent observations of single defect systems with quantum functionalities make silicon carbide (SiC) an ideal material to build such devices. Here, we demonstrate the fabrication of bright single photon emitting diodes. The electrically driven emitters display fully polarized output, superior photon statistics (with a count rate of $>$300 kHz), and stability in both continuous and pulsed modes, all at room temperature. The atomic origin of the single photon source is proposed. These results provide a foundation for the large scale integration of single photon sources into a broad range of applications, such as quantum cryptography or linear optics quantum computing.Comment: Main: 10 pages, 6 figures. Supplementary Information: 6 pages, 6 figure

Integration of Tobacco Treatment Services into Cancer Care at Stanford.

As part of a National Cancer Institute Moonshot P30 Supplement, the Stanford Cancer Center piloted and integrated tobacco treatment into cancer care. This quality improvement (QI) project reports on the process from initial pilot to adoption within 14 clinics. The Head and Neck Oncology Clinic was engaged first in January 2019 as a pilot site given staff receptivity, elevated smoking prevalence, and a high tobacco screening rate (95%) yet low levels of tobacco cessation treatment referrals (<10%) and patient engagement (<1% of smokers treated). To improve referrals and engagement, system changes included an automated "opt-out" referral process and provision of tobacco cessation treatment as a covered benefit with flexible delivery options that included phone and telemedicine. Screening rates increased to 99%, referrals to 100%, 74% of patients were reached by counselors, and 33% of those reached engaged in treatment. Patient-reported abstinence from all tobacco products at 6-month follow-up is 20%. In July 2019, two additional oncology clinics were added. In December 2019, less than one year from initiating the QI pilot, with demonstrated feasibility, acceptability, and efficacy, the tobacco treatment services were integrated into 14 clinics at Stanford Cancer Center

Effects of low energy electron irradiation on formation of nitrogen-vacancy centers in single-crystal diamond

Exposure to beams of low energy electrons (2 to 30 keV) in a scanning electron microscope locally induces formation of NV-centers without thermal annealing in diamonds that have been implanted with nitrogen ions. We find that non-thermal, electron beam induced NV-formation is about four times less efficient than thermal annealing. But NV-center formation in a consecutive thermal annealing step (800C) following exposure to low energy electrons increases by a factor of up to 1.8 compared to thermal annealing alone. These observations point to reconstruction of nitrogen-vacancy complexes induced by electronic excitations from low energy electrons as an NV-center formation mechanism and identify local electronic excitations as a means for spatially controlled room-temperature NV-center formation

Peningkatan Kemampuan Reading Comprehension melalui Pembelajaran Kooperatif Tipe Jigsaw

This research aims at analyzing (1) instructional design of reading comprehension 4 course through cooperative learning jigsaw type, (2) the implementation of cooperative learning jigsaw type on Reading Comprehension 4 Course, (3) the evaluation system of Reading Comprehension 4 Course through cooperative learning jigsaw type, and (4) the improvement of reading comprehension ability through cooperative learning jigsaw type on Reading Comprehension 4 Course. The research method used is classroom action research which is carried out on three cycles. The subjects were two classes: A-2D3-BI 1 and A-2D3-BI 2. Data collecting technique used in this research are evaluation sheet, observation, and test. The data were analyzed by using descriptive analysis. Cycle I discussed about science and technology, cycle II North American History, government, culture, and geographic, and cycle III about biography.Penelitian ini bertujuan menganalisis (1) desain perencanaan pembelajaran pemahaman membaca bahasa Inggris melalui pembelajaran kooperatif tipe jigsaw matakuliah Reading Comprehension 4; (2) pelaksanaan pembelajaran pemahaman membaca bahasa Inggris melalui pembelajaran kooperatif tipe jigsaw matakuliah Reading Comprehension 4; (3) sistem evaluasi pembelajaran pemahaman membaca bahasa Inggris melalui pembelajaran kooperatif tipe jigsaw; dan (4) peningkatan kemampuan pemahaman membaca bahasa Inggris mahasiswa melalui pembelajaran kooperatif tipe jigsaw matakuliah Reading Comprehension 4. Metode penelitian yang digunakan adalah Penelitian Tindakan yang dilaksanakan dalam tiga siklus. Subjek penelitian ini adalah mahasiswa kelas A-2D3-BI 1 dan A-2D3-BI 2. Teknik pengumpulan data yang digunakan dalam penelitian ini adalah lembar penilaian, observasi, dan tes. Analisis data yang digunakan adalah analisis deskripsi. Pada siklus I topik yang dibahas adalah teks tentang science and technology, siklus II North American History, government, culture, and geographic, dan siklus III tentang biography

Engineering chromium related single photon emitters in single crystal diamond

Color centers in diamond as single photon emitters, are leading candidates for future quantum devices due to their room temperature operation and photostability. The recently discovered chromium related centers are particularly attractive since they possess narrow bandwidth emission and a very short lifetime. In this paper we investigate the fabrication methodologies to engineer these centers in monolithic diamond. We show that the emitters can be successfully fabricated by ion implantation of chromium in conjunction with oxygen or sulfur. Furthermore, our results indicate that the background nitrogen concentration is an important parameter, which governs the probability of success to generate these centers.Comment: 14 pages, 5 figure

Quantum-confined single photon emission at room temperature from SiC tetrapods

Controlled engineering of isolated solid state quantum systems is one of the most prominent goals in modern nanotechnology. In this letter we demonstrate a previously unknown quantum system namely silicon carbide tetrapods. The tetrapods have a cubic polytype core (3C) and hexagonal polytype legs (4H)-a geometry that creates spontaneous polarization within a single tetrapod. Modeling of the tetrapod structures predicts that a bound exciton should exist at the 3C-4H interface. The simulations are confirmed by the observation of fully polarized and narrowband single photon emission from the tetrapods at room temperature. The single photon emission provides important insights into understanding the quantum confinement effects in non-spherical nanostructures. Our results pave the way to a new class of crystal phase nanomaterials that exhibit single photon emission at room temperature and therefore are suitable for sensing, quantum information and nanophotonics. © 2014 the Partner Organisations

Structure and vibrational spectra of carbon clusters in SiC

The electronic, structural and vibrational properties of small carbon interstitial and antisite clusters are investigated by ab initio methods in 3C and 4H-SiC. The defects possess sizable dissociation energies and may be formed via condensation of carbon interstitials, e.g. generated in the course of ion implantation. All considered defect complexes possess localized vibrational modes (LVM's) well above the SiC bulk phonon spectrum. In particular, the compact antisite clusters exhibit high-frequency LVM's up to 250meV. The isotope shifts resulting from a_{13}C enrichment are analyzed. In the light of these results, the photoluminescence centers D_{II} and P-U are discussed. The dicarbon antisite is identified as a plausible key ingredient of the D_{II}-center, whereas the carbon split-interstitial is a likely origin of the P-T centers. The comparison of the calculated and observed high-frequency modes suggests that the U-center is also a carbon-antisite based defect.Comment: 15 pages, 6 figures, accepted by Phys. Rev.