| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Chi, Xiaoming, et al.
(författare)
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Fractal superconducting nanowire single-photon detectors with reduced polarization sensitivity
- 2018
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Ingår i: Optics Letters. - : OPTICAL SOC AMER. - 0146-9592 .- 1539-4794. ; 43:20, s. 5017-5020
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate superconducting nanowire single-photon detectors (SNSPDs) based on a fractal design of the nanowires to reduce the polarization sensitivity of detection efficiency. We patterned niobium titanium nitride thin films into Peano curves with a linewidth of 100 nm and integrated the nanowires with optical microcavities to enhance their optical absorption. At a base temperature of 2.6 K, the fractal SNSPD exhibited a polarization-maximum device efficiency of 67% and a polarization-minimum device efficiency of 61% at a wavelength of 1550 nm. Therefore, the polarization sensitivity, defined as their ratio, was 1.1, lower than the polarization sensitivity of the SNSPDs in the meander design. The reduced polarization sensitivity of the detector could be maintained for higher-order spatial modes in multimode optical fibers and could tolerate misalignment between the optical mode and the detector. This fractal design is applicable to both amorphous and polycrystalline materials that are commonly used for making SNSPDs.
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| 3. |
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| 4. |
- Feng, Yifan, et al.
(författare)
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Fractal Superconducting Nanowire Single-Photon Detectors and Their Applications in Imaging
- 2022
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Ingår i: Proceedings of the 2022 Conference on Lasers and Electro-Optics Pacific Rim, CLEO/PR 2022. - : Optica Publishing Group.
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Konferensbidrag (refereegranskat)abstract
- We present our research on fractal superconducting nanowire single-photon detectors and their applications in light detection and ranging (LiDAR), full-Stokes polarimetric imaging, and non-line-of-sight imaging.
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| 5. |
- Feng, Yifan, et al.
(författare)
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Fractal Superconducting Nanowire Single-Photon Detectors and Their Applications in Imaging
- 2022
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Ingår i: 2022 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2022 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc..
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Konferensbidrag (refereegranskat)abstract
- We present our research on fractal superconducting nanowire single-photon detectors and their applications in light detection and ranging (LiDAR), full-Stokes polarimetric imaging, and non-line-of-sight imaging.
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| 6. |
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| 7. |
- Hu, Nan, et al.
(författare)
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Full-Stokes polarimetric measurements and imaging using a fractal superconducting nanowire single-photon detector
- 2022
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Ingår i: Optica. - : Optica Publishing Group. - 2334-2536. ; 9:4, s. 346-351
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Tidskriftsartikel (refereegranskat)abstract
- Measuring the states of polarization (SoP) of light is fundamentally important for applications ranging from communication, sensing, spectroscopy, imaging, to navigation. Superconducting nanowire single-photon detectors (SNSPDs) are ideal detectors of choice for faint-light detection and measurements, but SNSPDs themselves cannot resolve the SoP of photons. Here, based on a fractal SNSPD, we demonstrate a full-Stokes polarimetric measurement system that can measure arbitrary SoP of faint light. The measured SoPs are in excellent agreement with those of a state-of-the-art commercial polarimeter, but the sensitivity of our system reaches -86.6 dBm, which is 26.6 dB better than that of the commercial counterpart. As a direct application, we further demonstrate remote polarimetric imaging (i.e., polarimetric LiDAR) with a complete set of polarimetric contrast.
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| 8. |
- Hu, Nan, et al.
(författare)
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Photon-Counting LIDAR Based on a Fractal SNSPD
- 2021
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Ingår i: 2021 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXPOSITION (OFC). - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- We report on a photon-counting LIDAR system based on a polarization-insensitive fractal SNSPD with high detection efficiency and high timing resolution, and showcase depth imaging of an object at 1560 nm with millimeter depth resolution.
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| 9. |
- Hu, Xiaolong, et al.
(författare)
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Fractal superconducting nanowire single-photon detectors and their applications in polarimetric imaging
- 2024
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Ingår i: Advanced Photon Counting Techniques XVIII. - : SPIE-Intl Soc Optical Eng.
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Konferensbidrag (refereegranskat)abstract
- In this paper, we review the research and development of the fractal superconducting nanowire single-photon detectors (SNSPDs), including our demonstrations of high-performance devices and systems with over 80% system detection efficiency, negligibly low residual polarization sensitivity, and low timing jitter. Using the fractal SNSPDs, we demonstrate full-Stokes polarimetric imaging LiDAR.
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| 10. |
- Hu, Xiaolong, et al.
(författare)
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Superconducting nanowire single-photon detectors at the infrared spectrum range : detection efficiency and timing jitter
- 2019
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Ingår i: TERAHERTZ, RF, MILLIMETER, AND SUBMILLIMETER-WAVE TECHNOLOGY AND APPLICATIONS XII. - : SPIE. - 9781510624771
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Konferensbidrag (refereegranskat)abstract
- This paper reviews some recent research progress in superconducting nanowire single-photon detectors (SNSPDs) at the infrared spectrum range, with particular emphasis on detection efficiency and timing jitter. For detection efficiency, we present fractal SNSPDs with reduced polarization sensitivity; for timing jitter, we present two mechanisms of device timing jitter - vortex-crossing-induced timing jitter and spatial-inhomogeneity-induced timing jitter.
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| 11. |
- Hu, Xiaolong, et al.
(författare)
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Timing properties of superconducting nanowire single-photon detectors
- 2019
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Ingår i: Quantum Optics and Photon Counting 2019. - : SPIE - International Society for Optical Engineering. - 9781510627215
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Konferensbidrag (refereegranskat)abstract
- In this paper, we review theoretical and experimental research progress on timing properties of superconducting nanowire single-photon detectors, including six possible mechanisms that induce timing jitter and experiments towards ultra-low timing jitter.
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| 12. |
- Meng, Yun, et al.
(författare)
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Fractal Superconducting Nanowires Detect Infrared Single Photonswith 84% System Detection Efficiency, 1.02 Polarization Sensitivity,and 20.8 ps Timing Resolution br
- 2022
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 9:5, s. 1547-1553
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Tidskriftsartikel (refereegranskat)abstract
- The near-unity system detection efficiency (SDE) and excellent timing resolution of superconducting nanowiresingle-photon detectors (SNSPDs), combined with their other merits, have enabled many classical and quantum photonicapplications. However, the prevalent design based on meandering nanowires makes SDE dependent on the polarization states of theincident photons; for unpolarized light, the major merit of high SDE would get compromised, which could be detrimental to photon-starved applications. Here, we create SNSPDs with an arced fractal geometry that almost completely eliminates this polarizationdependence of the SDE, and we experimentally demonstrate 84 +/- 3% SDE, 1.02-0.02+0.06polarization sensitivity at the wavelength of1575 nm, and 20.8 ps timing jitter in a 0.1 W closed-cycle Gifford-McMahon cryocooler, at the base temperature of 2.0 K. Thisdemonstration provides a novel, practical device structure of SNSPDs, allowing for operation in the visible, near-infrared, and mid-infrared spectral ranges, and paves the way for polarization-insensitive single-photon detection with high SDE and high timingresolution.
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| 13. |
- Zou, Kai, et al.
(författare)
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Fractal superconducting nanowire single-photon detectors working in dual bands and their applications in free-space and underwater hybrid LIDAR
- 2023
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Ingår i: Optics Letters. - : Optica Publishing Group. - 0146-9592 .- 1539-4794. ; 48:2, s. 415-418
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a fiber-coupled fractal superconducting nanowire single-photon detector (SNSPD) system with minimum polarization dependence of detection efficiency. Its system detection efficiency (SDE) was maximized at the wavelength of 1540 nm, which was measured to be 91 +/- 4%; furthermore, we observed the second local maximum of SDE at the wavelength of 520 nm, which was measured to be 61 +/- 2%. This dual-band feature of SDE was due to the enhancement of the optical absorptance by two longitudinal resonance modes of the micro-cavity. By using high SDE with minimum polarization dependence in these two bands, we implemented a hybrid LIDAR for imaging the remote objects in free space and under water.
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| 14. |
- Zou, Kai, et al.
(författare)
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Superconducting Nanowire Single-Photon Detectors and Multi-Photon Detectors
- 2022
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Ingår i: Optics InfoBase Conference Papers. - : Optica Publishing Group (formerly OSA).
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Konferensbidrag (refereegranskat)abstract
- We present our research progress in superconducting nanowire single-photon detectors (SNSPDs) and multi-photon detectors (SNMPDs), including fractal SNSPDs with reduced polarization sensitivity, two mechanisms of device timing jitter, and SNMPDs integrated with current reservoirs.
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| 15. |
- Chen, Xiaolong, et al.
(författare)
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Nontrivial resource requirement in the early stage for containment of epidemics
- 2019
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Ingår i: Physical review. E. - 2470-0045 .- 2470-0053. ; 100:3
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Tidskriftsartikel (refereegranskat)abstract
- During epidemic control, containment of the disease is usually achieved through increasing a devoted resource to reduce the infectiousness. However, the impact of this resource expenditure has not been studied quantitatively. For disease spread, the recovery rate can be positively correlated with the average amount of resource devoted to infected individuals. By incorporating this relation we build a novel model and find that insufficient resource leads to an abrupt increase in the infected population size, which is in marked contrast with the continuous phase transitions believed previously. Counterintuitively, this abrupt phase transition is more pronounced in less contagious diseases. Furthermore, we find that even for a single infection source, the public resource needs to be available in a significant amount, which is proportional to the total population size, to ensure epidemic containment. Our findings provide a theoretical foundation for efficient epidemic containment strategies in the early stage.
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| 16. |
- Hao, Zifan, et al.
(författare)
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High-performance eight-channel system with fractal superconducting nanowire single-photon detectors
- 2024
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Ingår i: Chip. - : Elsevier B.V.. - 2709-4723 .- 2772-2724. ; 3:2
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Tidskriftsartikel (refereegranskat)abstract
- Superconducting nanowire single-photon detectors (SNSPDs) have become a mainstream photon-counting technology that has been widely applied in various scenarios. So far, most multi-channel SNSPD systems, either reported in literature or commercially available, are polarization sensitive, that is, the system detection efficiency (SDE) of each channel is dependent on the state of polarization of the to-be-detected photons. Here, we reported an eight-channel system with fractal SNSPDs working in the wavelength range of 930 to 940 nm, which are all featured with low polarization sensitivity. In a close-cycled Gifford-McMahon cryocooler system with the base temperature of 2.2 K, we installed and compared the performance of two types of devices: (1) SNSPD, composed of a single, continuous nanowire and (2) superconducting nanowire avalanche photodetector (SNAP), composed of 16 cascaded units of two nanowires electrically connected in parallel. The highest SDE among the eight channels reaches 96−5+4%, with the polarization sensitivity of 1.02 and a dark-count rate of 13 counts per second. The average SDE for eight channels for all states of polarization is estimated to be 90 ± 5%. It is concluded that both the SNSPDs and the SNAPs can reach saturated, high SDE at the wavelength of interest, and the SNSPDs show lower dark-count (false-count) rates, whereas the SNAPs show better properties in the time domain. With the adoption of this system, we showcased the measurements of the second-order photon-correlation functions of light emission from a single-photon source based on a semiconductor quantum dot and from a pulsed laser. It is believed that this work will provide new choices of systems with single-photon detectors combining the merits of high SDE, low polarization sensitivity, and low noise that can be tailored for different applications.
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| 17. |
- Hao, Zifan, et al.
(författare)
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Multi-channel system with high-performance fractal superconducting nanowire single-photon detectors
- 2024
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Ingår i: 2024 Optical Fiber Communications Conference and Exhibition, OFC 2024 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc..
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Konferensbidrag (refereegranskat)abstract
- We report on an eight-channel fractal SNSPD system in the wavelength range of 940 nm with minimal polarization sensitivity. The best channel exhibits 96% system detection efficiency and 19 cps dark-count rate.
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| 18. |
- Higgins, Charlotte, et al.
(författare)
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Planning tools and methods for systems facing high levels of distributed energy resources
- 2023
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Konferensbidrag (refereegranskat)abstract
- It is important for utilities to plan for Distributed Energy Resources (DER) uptake by representing and modelling their characteristics using appropriate assumptions, methods and tools. Large-scale DER deployment impacts power flows and power system performance in various complex ways as well as potentially contributing to ancillary services. In this paper, we explore state of the art planning methods and tools being developed and deployed by utilities internationally, for systems facing high levels of distributed energy resources. This is part of technical working group C1 6.42 and our findings will be further expanded in the full technical brochure to be published in 2023. A survey of 17 international utilities was carried out to inform our study. In network planning, DER can broadly be treated similar to any other energy source. However, complexity arises particularly from several aspects: 1) how to model the impact of diverse, distributed DER at transmission and distribution network level and 2) how to model and characterise the impact of higher uncertainty from DER. This has led to a wider range of study conditions being considered using clustered time series and probabilistic methods to efficiently capture varying geospatial generation and demand during different times and seasons.Novel modelling approaches to representing DER in steady state and dynamic/transient studies have also been developed. These can have strengths and weaknesses and simulations of severe grid disturbances often fail to reproduce the widespread tripping of DER that can occur in reality, for example. Plant specific tuning for DER models and EMT modelling of high penetration networks are under development to better model behaviour under transient conditions. In order to provide greater whole-system representation, EMTP type numerical tools have been used to solve load flow problems with both transmission systems and distribution systems integrated into one network model. Hybrid/co-simulation approaches and dynamic phasor techniques are also being explored. More sophisticated and innovative statistical methods are also being applied to understand the impacts of DER and other uncertainty. Development of resilience standards and a more standardised approach to resilience modelling will support the improved consideration and contribution of DER in a resilient, decarbonised grid.
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| 19. |
- Li, Xiaolong, 1991, et al.
(författare)
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Solid solution softening at room temperature and hardening at elevated temperatures: a case by minor Mn addition in a (HfNbTi) 85 Mo 15 refractory high entropy alloy
- 2023
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Ingår i: Materials Research Express. - 2053-1591. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- To address the conflict between room-temperature (RT) ductility and high-temperature (HT) strength in single phase bcc-structured refractory high entropy alloys, here we propose to use minor alloying to achieve solid solution softening at RT and simultaneously, solid solution hardening at HT. Our strategy was manifested by minor Mn additions in a RT brittle (HfNbTi)85Mo15 refractory high entropy alloy, where nominal Mn additions ranging from 2 at. % down to 0.03 at. % were seen to soften the base (HfNbTi)85Mo15 alloy at RT, while to harden the base alloy at the temperature range from 400 to 800 °C. The yield stress in all studied alloys showed a three-stage pattern, characterized by a temperature dependent stage at temperatures below 400 °C, followed by a temperature independent stage at intermediate temperatures ranging from 400 to 800 °C, and finally another temperature dependent stage at temperatures higher than 800 °C. The mechanisms for solid solution softening and solid solution hardening in single phase bcc-structured refractory high entropy alloys were discussed, together with their temperature dependence.
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| 20. |
- Zadeh, Iman Esmaeil, et al.
(författare)
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Efficient Single-Photon Detection with 7.7 ps Time Resolution for Photon-Correlation Measurements
- 2020
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Ingår i: ACS Photonics. - : AMER CHEMICAL SOC. - 2330-4022. ; 7:7, s. 1780-1787
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Tidskriftsartikel (refereegranskat)abstract
- A broad range of scientific and industrial disciplines require precise optical measurements at very low light levels. Single-photon detectors combining high efficiency and high time resolution are pivotal in such experiments. By using relatively thick films of NbTiN (8-11 nm) and improving the pattern fidelity of the nanostructure of the superconducting nanowire single-photon detectors (SNSPD), we fabricated devices demonstrating superior performance over all previously reported detectors in the combination of efficiency and time resolution. Our findings prove that small variations in the nanowire width, in the order of a few nanometers, can lead to a significant penalty on their temporal response. Addressing these issues, we consistently achieved high time resolution (best device 7.7 ps, other devices similar to 10-16 ps) simultaneously with high system detection efficiencies (80-90%) in the wavelength range of 780-1000 nm, as well as in the telecom bands (1310-1550 nm). The use of thicker films allowed us to fabricate large-area multipixel devices with homogeneous pixel performance. We first fabricated and characterized a 100 x 100 mu m(2) 16-pixel detector and showed there was little variation among individual pixels. Additionally, to showcase the power of our platform, we fabricated and characterized 4-pixel multimode fiber-coupled detectors and carried out photon-correlation experiments on a nanowire quantum dot resulting in g(2) (0) values lower than 0.04. The multipixel detectors alleviate the need for beamsplitters and can be used for higher order correlations with promising prospects not only in the field of quantum optics, but also in bioimaging applications, such as fluorescence microscopy and positron emission tomography.
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| 21. |
- Zhang, Xudong, et al.
(författare)
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C-60/Na4FeO3/Li3V2(PO4)(3)/soft carbon quaternary hybrid superstructure for high-performance battery-supercapacitor hybrid devices
- 2020
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Ingår i: NPG ASIA MATERIALS. - : NATURE PUBLISHING GROUP. - 1884-4049 .- 1884-4057. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- To develop battery-supercapacitor hybrid devices with high energy and power densities, we propose a rational design of a quaternary hybrid superstructure by using a high-energy biotemplate. This new superstructure is composed of stable fullerene C-60 nanocages, electroactive Na4FeO3, high-energy Li3V2(PO4)(3) and soft carbon as well as tubular ordered mesoporous channels. This design takes advantage of the unique properties of each component, resulting in nanocomposites with synergistic effects to improve the charge transfer and energy storage. We found that this quaternary hybrid electrode has both high energy and power densities as well as a long cycling life in a Li/Na mixed-ion electrolyte, outperforming a multitude of other battery-supercapacitor hybrid devices reported thus far. The charge storage mechanisms of this hybrid superstructure are proposed for optimizing the electrode design.
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