| 1. |
- Almlof, Jonas, et al.
(författare)
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Creating and detecting specious randomness
- 2023
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Ingår i: EPJ QUANTUM TECHNOLOGY. - : Springer Nature. - 2662-4400 .- 2196-0763. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- We present a new test of non-randomness that tests both the lower and the upper critical limit of a chi 2-statistic. While checking the upper critical value has been employed by other tests, we argue that also the lower critical value should be examined for non-randomness. To this end, we prepare a binary sequence where all possible bit strings of a certain length occurs the same number of times and demonstrate that such sequences pass a well-known suite of tests for non-randomness. We show that such sequences can be compressed, and therefore are somewhat predictable and thus not fully random. The presented test can detect such non-randomness, and its novelty rests on analysing fixed-length bit string frequencies that lie closer to the a priori probabilities than could be expected by chance alone.
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| 2. |
- Gyger, Samuel, et al.
(författare)
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Metropolitan Single-Photon Distribution at 1550 nm for Random Number Generation
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics, CLEO 2023. - : Institute of Electrical and Electronics Engineers Inc..
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Konferensbidrag (refereegranskat)abstract
- Quantum communication networks are used for QKD and metrological applications. We present research connecting two nodes ≈ 20 kilometers apart over the municipal fiber network using semiconductor quantum dots emitting at 1550 nm.
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| 3. |
- Gyger, Samuel, et al.
(författare)
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Metropolitan single-photon distribution at 1550 nm for random number generation
- 2022
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 121:19, s. 194003-
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Tidskriftsartikel (refereegranskat)abstract
- Quantum communication networks will connect future generations of quantum processors, enable metrological applications, and provide security through quantum key distribution. We present a testbed that is part of the municipal fiber network in the greater Stockholm metropolitan area for quantum resource distribution through a 20 km long fiber based on semiconductor quantum dots emitting in the telecom C-band. We utilize the service to generate random numbers passing the NIST test suite SP800-22 at a subscriber 8 km outside of the city with a bit rate of 23.4 kbit/s.
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| 4. |
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| 5. |
- Urban, Patryk, et al.
(författare)
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Detection of Fiber Faults in Passive Optical Networks
- 2013
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Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 5:11, s. 1111-1121
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Tidskriftsartikel (refereegranskat)abstract
- Wider deployment of fiber in the last mile is driven by increased customer needs for broadband communication services. This deployment requires solutions that reduce operational expenditures for the operator. A cost-efficient fully reliable and accurate monitoring solution supporting fault detection, identification, and localization in different fiber access architectures will be essential. In this article, we present a fast, automatic, and precise monitoring method applicable to both power-splitter- and wavelength-router-based passive optical networks through the combined techniques of optical time domain reflectometry and optical transceiver monitoring. The description of the architecture, components, and process flow is followed by tests on setups with live data transmission.
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| 6. |
- Feyer, Vitaliy, et al.
(författare)
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Tautomerism in Cytosine and Uracil : An Experimental and Theoretical Core Level Spectroscopic Study
- 2009
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 113:19, s. 5736-5742
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Tidskriftsartikel (refereegranskat)abstract
- The O, N, and C 1s core level photoemission spectra of the nucleobases cytosine and uracil have been measured in the vapor phase, and the results have been interpreted via theoretical calculations. Our calculations accurately predict the relative binding energies of the core level features observed in the experimental photoemission results and provide a full assignment. In agreement with previous work, a single tautomer of uracil is populated at 405 K, giving rise to relatively simple spectra. At 450 K, three tautomers of cytosine, one of which may consist of two rotamers, are identified, and their populations are determined. This resolves inconsistencies between recent laser studies of this molecule in which the rare imino-oxo tautomer was not observed and older microwave spectra in which it was reported.
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| 7. |
- Kivimaki, A., et al.
(författare)
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Fluorescence emission at core-to-Rydberg excitations in the N-2 molecule
- 2009
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 42:18
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescence emission at the N 1s edge of the N-2 molecule has been studied with synchrotron radiation excitation. The partial fluorescence yields in the ultraviolet (250-320 nm) and visible (300-650 nm) wavelengths were collected by scanning the photon energy across the core-to-Rydberg excitations and the N 1s ionization potential (IP). When compared to the total ion yield, both fluorescence yields are most enhanced at the excitations to high Rydberg orbitals. A discrete structure appears just below the N 1s IP only in the UV yield and is assigned to core-valence doubly excited states. Dispersed fluorescence spectra in selected wavelength windows were measured at several photon energies in order to find out which fragments are responsible for the enhancement of fluorescence emission just below the N 1s IP. The excitation functions determined and considerations on de-excitation pathways indicate that the main responsible is the N+ ion.
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| 8. |
- Kivimaki, A., et al.
(författare)
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Line shape narrowing in the ultraviolet yield at the N 1s -> pi* resonance of the N-2 molecule
- 2009
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 42:7
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Tidskriftsartikel (refereegranskat)abstract
- The intensity of fluorescence emission in the wavelength region of 250-320 nm has been measured across the N 1s -> pi* resonance of the N-2 molecule. It displays a narrower line shape than the total ion yield recorded simultaneously. We explain the finding by the particularities of the resonant Auger transitions from the N 1s(-1) pi* state to the D-2 Pi(g) state in N-2(+) and by the subsequent D-2 Pi(g) -> A(2)Pi(u) emission.
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| 9. |
- Plekan, Oksana, et al.
(författare)
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An Experimental and Theoretical Core-Level Study of Tautomerism in Guanine
- 2009
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 113:33, s. 9376-9385
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Tidskriftsartikel (refereegranskat)abstract
- The core level photoemission and near edge X-ray photoabsorption spectra of guanine in the gas phase have been measured and the results interpreted with the aid of high level ab initio calculations. Tautomers are clearly identified spectroscopically, and their relative free energies and Boltzmann populations at the temperature of the experiment (600 K) have been calculated and compared with the experimental results and with previous calculations. We obtain good agreement between experiment and the Boltzmann weighted theoretical photoemission spectra, which allows a quantitative determination of the ratio of oxo to hydroxy tautomer populations. For the photoabsorption spectra, good agreement is found for the C 1s and I 1s spectra but only fair agreement for the N 1s edge.
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| 10. |
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