| 1. |
- Azzouz, Hatim, et al.
(författare)
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Capacitive readout and gating of superconducting single photon detectors
- 2013
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 84:5
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Tidskriftsartikel (refereegranskat)abstract
- We propose and develop a readout scheme for superconducting single-photon detectors based on an integrated circuit, relaxing the need for large bandwidth amplification and resulting in voltage steps proportional to the number of detected photons. We also demonstrate time gating, to filter scattered light in time and reduce dark counts. This could lead to a higher signal-to-noise ratio. The gate pulse is generated on the detection of a photon created by a spontaneous parametric down-conversion source, heralding the presence of a second photon. These two schemes could find applications within advanced multi-array imaging detection systems.
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| 2. |
- Azzouz, Hatim, et al.
(författare)
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Efficient single particle detection with a superconducting nanowire
- 2012
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Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- Detection of alpha- and beta-particles is of paramount importance in a wide range of applications. Current particle detectors are all macroscopic and have limited time resolution. We demonstrate a nanoscale particle detector with a small detection volume, high detection efficiency, short dead times and low dark count levels. We measure alpha- and beta-particle detection efficiencies close to unity using different sources and also demonstrate blindness towards gamma-rays. Our nanoscale detector offers particle detection measurements with unprecendented spatial resolution.
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| 3. |
- Barnes, W. L., et al.
(författare)
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Solid-state single photon sources : light collection strategies
- 2002
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Ingår i: European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 18:2, s. 197-210
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Tidskriftsartikel (refereegranskat)abstract
- We examine the problem of efficiently collecting the photons produced by solid-state single photon sources. The extent of the problem is first established with the aid of simple physical concepts. Several approaches to improving the collection efficiency are then examined and are broadly categorized into two types. First are those based on cavity quantum dynamics, in which the pathways by which the source may emit a photon are restricted, thus channeling emission into one desired mode. Second are those where we try to reshape the free space modes into a target mode in an optimal way, by means of refraction, without fundamentally altering the way in which the source emits. Respectively, we examine a variety of microcavities and solid immersion lenses. Whilst we find that the micropillar microcavities offer the highest collection efficiency (similar to70%), choosing this approach may not always be appropriate due to other constraints. Details of the different approaches, their merits and drawbacks are discussed in detail.
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| 4. |
- Chen, Wei, et al.
(författare)
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Crystal field, phonon coupling and emission shift of Mn2+ in ZnS:Mn nanoparticles
- 2001
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 89, s. 1120-1129
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Tidskriftsartikel (refereegranskat)abstract
- The Mn2+ emission wavelengths are at 591, 588, 581 and 570 nm, respectively, for the similar to 10, similar to4.5, similar to3.5 nm sized nanoparticles and the ZnS:Mn nanoparticles formed in an ultrastable zeolite-Y. To reveal the cause for the shift, the crystal field and phonon coupling were investigated. The results show that the predominant factor for the shift is the phonon coupling, whose strength is size dependent and is determined by both the size confinement and the surface modification of the nanoparticles. Although the crystal field strength decreases with the decreasing of the particle size, its change has little contribution to the emission shift of Mn2+ in ZnS:Mn nanoparticles. (C) 2001 American Institute of Physics.
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| 5. |
- Chen, Wei, et al.
(författare)
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Energy structure and fluorescence of Eu2+ in ZnS:Eu nanoparticles
- 2000
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Ingår i: Physical Review B. - 1098-0121. ; 61:16, s. 11021-11024
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Tidskriftsartikel (refereegranskat)abstract
- Eu2+-doped ZnS nanoparticles with an average size of around 3 nm were prepared, and an emission band around 530 nm was observed. By heating in air at 150 degrees C, this emission decreased, while the typical sharp line emission of Eu3+ increased. This suggests that the emission around 530 nm is from intraion transition of Eu2+: In bulk ZnS:Eu2+, no intraion transition of Eu2+ was observed because the excited states of Eu2+ are degenerate with the continuum of the ZnS conduction band. We show that the band gap in ZnS:Eu2+ nanoparticles opens up due to quantum confinement, such that the conduction band of ZnS is higher than the first excited state of Eu2+, thus enabling the intraion transition of Eu2+ to occur.
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| 6. |
- Chen, W, et al.
(författare)
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Size dependence of Eu2+ fluorescence in ZnS:Eu2+ nanoparticles
- 2001
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 89:5, s. 2671-2675
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Tidskriftsartikel (refereegranskat)abstract
- The emission bands of the 4.2, 3.2 and 2.6 nm sized ZnS:Eu2+ nanoparticles are peaking at 670, 580 and 520 nm, respectively. The emission of the 4.2 nm sized nanoparticles originates from the recombination of the Eu2+-bound exciton, while the emission of the 3.2 and 2.6 nm sized nanoparticles is from the Eu2+ intra-ion transition of 4f(6)5d(1)(t(2g))-4f(7). Possible mechanisms for the size dependence of the 4f(6)5d(1)(t(2g))-4f(7) transition of Eu2+ in ZnS:Eu2+ nanoparticles were investigated, and it was concluded that the decreases in the electron-phonon coupling and in crystal field strength upon a decrease in size are the two major factors responsible for the shift. (C) 2001 American Institute of Physics.
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| 7. |
- Fälth, S, et al.
(författare)
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Isolating single selected quantum dots using cryogenic photolithography
- 2002
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Ingår i: PHYSICA SCRIPTA. - 0031-8949 .- 1402-4896. ; T101, s. 133-135
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Konferensbidrag (refereegranskat)abstract
- We propose and demonstrate a technique combining micro-photoluminescence imaging with scanning photolithography at Cryogenic temperatures for creating photoresist masks at designated locations relative to single selected self-assembled quantum dots. The technique is demonstrated by producing a photoresist mask on top of a single selected InP quantum dot imbedded in GaInP. A mesa containing the quantum dot is then created by wet chemical etching. The combination of micro-photoluminescence and scanning photolithography relies on the use of two different lasers with a micro-photoluminescence setup, each laser having different power, focusing and wavelength. The resulting structure enables many experiments and applications in the emerging field of single quantum dot physics.
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| 8. |
- Haffouz, Sofiane, et al.
(författare)
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Bright Single InAsP Quantum Dots at Telecom Wavelengths in Position-Controlled InP Nanowires : The Role of the Photonic Waveguide
- 2018
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Ingår i: Nano letters (Print). - : AMER CHEMICAL SOC. - 1530-6984 .- 1530-6992. ; 18:5, s. 3047-3052
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Tidskriftsartikel (refereegranskat)abstract
- We report on the site-selected growth of bright single InAsP quantum dots embedded within InP photonic nanowire waveguides emitting at telecom wavelengths. We demonstrate a dramatic dependence of the emission rate on both the emission wavelength and the nanowire diameter. With an appropriately designed waveguide, tailored to the emission wavelength of the dot, an increase in the count rate by nearly 2 orders of magnitude (0.4 to 35 kcps) is obtained for quantum dots emitting in the telecom O-band, showing high single-photon purity with multiphoton emission probabilities down to 2%. Using emission-wavelength-optimized waveguides, we demonstrate bright, narrow-line-width emission from single InAsP quantum dots with an unprecedented tuning range of 880 to 1550 nm. These results pave the way toward efficient single-photon sources at telecom wavelengths using deterministically grown InAsP/InP nanowire quantum dots.
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| 9. |
- 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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| 10. |
- Håkanson, Ulf, et al.
(författare)
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Luminescence polarization of ordered GaInP/InP islands
- 2003
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:4, s. 627-629
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Tidskriftsartikel (refereegranskat)abstract
- The luminescence polarization properties of GaInP islands have been investigated. The islands, which form during overgrowth of InP quantum dots, were studied using scanning tunneling luminescence (STL) and photoluminescence (PL). STL from these islands shows emission at an energy below the main emission peak of the bulk GaInP. The linear PL polarization anisotropy was measured at low temperature, for which the emission from the islands shows high polarization anisotropy. The intensity maximum for the emission occurs for light polarized parallel to the elongation of the islands. The observed linear PL polarization anisotropy indicates the presence of highly ordered domains of GaInP in the islands. (C) 2003 American Institute of Physics.
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