Johannes Skaar

• Hågenvik, Hans Olaf & Skaar, Johannes (2019). Magnetic permeability in Fresnel’s equation. Journal of the Optical Society of America. B, Optical physics.  ISSN 0740-3224.  36(5), s 1386- 1395 . doi: 10.1364/JOSAB.36.001386 Full text in Research Archive.
• Skaar, Johannes (2019). Fresnel's equations in statics and quasistatics. European journal of physics.  ISSN 0143-0807.  40(4) . doi: 10.1088/1361-6404/ab166b Full text in Research Archive.
• Skaar, Johannes; Hågenvik, Hans Olaf & Dirdal, Christopher Andrew (2019). Four definitions of magnetic permeability for periodic metamaterials. Physical review B (PRB).  ISSN 2469-9950.  99(6) . doi: 10.1103/PhysRevB.99.064407 Full text in Research Archive. Show summary

  We state and compare four different definitions of magnetic permeability for periodic, artificial media, or metamaterials. The connections among them, and properties in general, are discussed in detail, including causality, passivity, symmetry, asymptotic behavior, and origin dependence. The analysis is limited to metamaterials made from linear and nonmagnetic constituents

• Dirdal, Christopher Andrew; Hågenvik, Hans Olaf; Haave, Haakon Aamodt & Skaar, Johannes (2018). Higher order multipoles in metamaterial homogenization. IEEE Transactions on Antennas and Propagation.  ISSN 0018-926X.  66(11), s 6403- 6407 . doi: 10.1109/TAP.2018.2863742 Full text in Research Archive. Show summary

  The higher order multipoles above the electric quadrupole are commonly neglected in metamaterial homogenization. We show that they nevertheless can be significant when the second-order spatial dispersive effects, such as the magnetic response, are considered. In this respect, they can be equally important as the magnetization and quadrupole terms, and should not be automatically neglected.

• Dirdal, Christopher Andrew & Skaar, Johannes (2018). Diamagnetism and the dispersion of the magnetic permeability. European Physical Journal B : Condensed Matter Physics.  ISSN 1434-6028.  91(6) . doi: 10.1140/epjb/e2018-80515-1 Full text in Research Archive.
• Joshi, Siddarth Koduru; Pienaar, Jacques; Ralph, Timothy C.; Cacciapuoti, Luigi; McCutcheon, Will; Rarity, John; Giggenbach, Dirk; Lim, Jin Gyu; Makarov, Vadim; Fuentes, Ivette; Scheidl, Thomas; Beckert, Erik; Bourennane, Mohamed; Bruschi, David Edward; Cabello, Adán; Capmany, Jose; Carrasco-Casado, Alberto; Diamanti, Eleni; Dušek, Miloslav; Elser, Dominique; Gulinatti, Angelo; Hadfield, Robert H.; Jennewein, Thomas; Kaltenbaek, Rainer; Krainak, Michael A.; Lo, Hoi-Kwong; Marquardt, Christoph; Milburn, Gerard; Peev, Momtchil; Poppe, Andreas; Pruneri, Valerio; Renner, Renato; Salomon, Christophe; Skaar, Johannes; Solomos, Nikolaos; Stipčević, Mario; Torres, Juan P.; Toyoshima, Morio; Villoresi, Paolo; Walmsley, Ian; Weihs, Gregor; Weinfurter, Harald; Zeilinger, Anton; Żukowski, Marek & Ursin, Rupert (2018). Space QUEST mission proposal: experimentally testing decoherence due to gravity. New Journal of Physics.  ISSN 1367-2630.  20:063016(6), s 1- 22 . doi: 10.1088/1367-2630/aac58b Full text in Research Archive.
• Hågenvik, Hans Olaf; Bløtekjær, Kjell & Skaar, Johannes (2017). Dielectric media considered as vacuum with sources. American Journal of Physics (AJP).  ISSN 0002-9505.  85(11), s 830- 833 . doi: 10.1119/1.5003810 Full text in Research Archive.
• Marøy, Øystein; Makarov, Vadim & Skaar, Johannes (2017). Secure detection in quantum key distribution by real-time calibration of receiver. Quantum Science and Technology.  ISSN 2058-9565.  2(4) . doi: 10.1088/2058-9565/aa83c9 Full text in Research Archive.
• Dirdal, Christopher Andrew; Bondevik, Tarjei & Skaar, Johannes (2015). Relaxed dispersion constraints and metamaterial effective parameters with physical meaning for all frequencies. Physical Review B. Condensed Matter and Materials Physics.  ISSN 1098-0121.  91(13) . doi: 10.1103/PhysRevB.91.134102
• Dirdal, Christopher Andrew & Skaar, Johannes (2015). Superposing Lorentzian resonance functions towards engineering target responses, In Said Zouhdi; Nikolay Zheludev & Jing Hua Teng (ed.),  Meta'14 Singapore Proceedings.  META conference.  ISBN 978-2-9545460-4-9.  Artikkel.  s 53 - 58
• Hågenvik, Hans Olaf; Malema, Markus Edward & Skaar, Johannes (2015). Fourier theory of linear gain media. Physical Review A. Atomic, Molecular, and Optical Physics (PRA).  ISSN 1050-2947.  91(4) . doi: 10.1103/PhysRevA.91.043826
• Hågenvik, Hans Olaf & Skaar, Johannes (2015). Fourier-Laplace analysis and instabilities of a gainy slab. Journal of the Optical Society of America. B, Optical physics.  ISSN 0740-3224.  32(9), s 1947- 1953 . doi: 10.1364/JOSAB.32.001947
• Svendsen, Guro Kristin; Skaar, Johannes; Weman, Helge & Dupertuis, Marc-André (2015). Symmetries and optical transitions of hexagonal quantum dots in GaAs/AlGaAs nanowires. Physical Review B. Condensed Matter and Materials Physics.  ISSN 1098-0121.  92(20) . doi: 10.1103/PhysRevB.92.205303
• Bugge, Audun Nystad; Sauge, Sebastien; Ghazali, Aina Mardhiyah M.; Skaar, Johannes; Lydersen, Lars Vincent Van de Wiel & Makarov, Vadim (2014). Laser damage helps the eavesdropper in quantum cryptography. Physical Review Letters.  ISSN 0031-9007.  112(7:070503) . doi: 10.1103/PhysRevLett.112.070503
• Liu, Qin; Lamas-Linares, Antia; Kurtsiefer, Christian; Skaar, Johannes; Makarov, Vadim & Gerhardt, Ilja (2014). A universal setup for active control of a single-photon detector. Review of Scientific Instruments.  ISSN 0034-6748.  85(1) . doi: 10.1063/1.4854615
• Marøy, Øystein; Gudmundsen, Magne; Lydersen, Lars Vincent Van de Wiel & Skaar, Johannes (2014). Error estimation, error correction and verification in quantum key distribution. IET Information Security.  ISSN 1751-8709.  8(5), s 277- 282 . doi: 10.1049/iet-ifs.2012.0333
• Dirdal, Christopher Andrew & Skaar, Johannes (2013). Negative refraction in causal media by evaluating polar paths for rational functions. Journal of the Optical Society of America. B, Optical physics.  ISSN 0740-3224.  30(2), s 370- 376 . doi: 10.1364/JOSAB.30.000370
• Dirdal, Christopher Andrew & Skaar, Johannes (2013). Superpositions of Lorentzians as the class of causal functions. Physical Review A. Atomic, Molecular, and Optical Physics (PRA).  ISSN 1050-2947.  88(3) . doi: 10.1103/PhysRevA.88.033834
• Svendsen, Guro Kristin; Haakestad, Magnus Willum & Skaar, Johannes (2013). Reciprocity and the scattering matrix of waveguide modes. Physical Review A. Atomic, Molecular, and Optical Physics (PRA).  ISSN 1050-2947.  87(1) . doi: 10.1103/PhysRevA.87.013838
• Skaar, Johannes & Haakestad, Magnus Willum (2012). Inverse scattering of dispersive stratified structures. Journal of the Optical Society of America. B, Optical physics.  ISSN 0740-3224.  29(9), s 2438- 2445 . doi: 10.1364/JOSAB.29.002438 Show summary

  We consider the inverse-scattering problem of retrieving the structural parameters of a stratified medium consisting of dispersive materials, given knowledge of the complex reflection coefficient in a finite frequency range. It is shown that the inverse-scattering problem does not have a unique solution in general. When the dispersion is sufficiently small, such that the time-domain Fresnel reflections have durations less than the round-trip time in the layers, the solution is unique and can be found by layer peeling. Numerical examples with dispersive and lossy media are given, demonstrating the usefulness of the method for, e.g., terahertz technology.

• Svendsen, Guro Kristin; Weman, Helge & Skaar, Johannes (2012). Investigations of Bragg reflectors in nanowire lasers. Journal of Applied Physics.  ISSN 0021-8979.  111(12) . doi: 10.1063/1.4729529
• Andresen, Marte Pernille Hatlo; Krogstad, Harald E & Skaar, Johannes (2011). Inverse scattering of two-dimensional photonic structures by layer stripping. Journal of the Optical Society of America. B, Optical physics.  ISSN 0740-3224.  28(4), s 689- 696 . doi: 10.1364/josab.28.000689
• Gerhardt, Ilja; Liu, Qin; Lamas-linares, Antia; Skaar, Johannes; Kurtsiefer, Christian & Makarov, Vadim (2011). Full-field implementation of a perfect eavesdropper on a quantum cryptography system. Nature Communications.  ISSN 2041-1723.  2(349) . doi: 10.1038/ncomms1348 Full text in Research Archive. Show summary

  Quantum key distribution (QKD) allows two remote parties to grow a shared secret key. Its security is founded on the principles of quantum mechanics, but in reality it significantly relies on the physical implementation. Technological imperfections of QKD systems have been previously explored, but no attack on an established QKD connection has been realized so far. Here we show the first full-field implementation of a complete attack on a running QKD connection. An installed eavesdropper obtains the entire 'secret' key, while none of the parameters monitored by the legitimate parties indicate a security breach. This confirms that non-idealities in physical implementations of QKD can be fully practically exploitable, and must be given increased scrutiny if quantum cryptography is to become highly secure.

• Gerhardt, Ilja; Liu, Qin; Lamas-linares, Antia; Skaar, Johannes; Scarani, Valerio; Makarov, Vadim & Kurtsiefer, Christian (2011). Experimentally faking the violation of Bell’s inequalities. Physical Review Letters.  ISSN 0031-9007.  107(170404) . doi: 10.1103/PhysRevLett.107.170404 Show summary

  Entanglement witnesses such as Bell inequalities are frequently used to prove the non-classicality of a light source and its suitability for further tasks. By demonstrating Bell inequality violations using classical light in common experimental arrangements, we highlight why strict locality and efficiency conditions are not optional, particularly in security-related scenarios.

• Grepstad, Jon Olav & Skaar, Johannes (2011). Does evanescent gain exist?, In W. Ross Stone (ed.),  Proceedings of the XXXth URSI General Assembly in Istanbul (August 2011).  IEEE conference proceedings.  ISBN 978-1-4244-5117-3.  Artikkel.
• Grepstad, Jon Olav & Skaar, Johannes (2011). Total internal reflection and evanescent gain. Optics Express.  ISSN 1094-4087.  19(22), s 21404- 21418 . doi: 10.1364/OE.19.021404 Full text in Research Archive.

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• Nilsen, Fabian Skalleberg & Skaar, Johannes (2020, 24. februar). Østlandssendingen - er det mulig å forsyne seg selv med strøm ved hjelp av spinningsykler og tredemøller?. [Radio].  NRK P1.
• Fedorov, Aleksey; Gerhardt, Ilja; Huang, Anqi; Jogenfors, Jonathan; Kurochkin, Yury; Lamas-Linares, Antia; Larsson, Jan-Åke; Leuchs, Gerd; Lydersen, Lars Vincent Van de Wiel; Makarov, Vadim & Skaar, Johannes (2019). Comment on 'Inherent security of phase coding quantum key distribution systems against detector blinding attacks' (2018 Laser Phys. Lett. 15 095203). Laser Physics Letters.  ISSN 1612-2011.  16 . doi: 10.1088/1612-202X/aaf22d
• Hågenvik, Hans Olaf & Skaar, Johannes (2019). Analysis of active and passive metamaterials.
• Jemterud, Torkild; Skaar, Johannes; Eidsvoll, David & Iqbal, Yasmin Sofia (2019, 01. november). Abels tårn. [Radio].  NRK P2.
• Risan, Lars & Skaar, Johannes (2019). SENT-kveld på Teknisk museum: Foredrag om kvantedatamaskiner.
• Skaar, Johannes (2019). Musikk og matematikk.
• Dirdal, Christopher Andrew; Hågenvik, Hans Olaf; Haave, Haakon Aamodt & Skaar, Johannes (2018). Higher order multipoles in metamaterial homogenization.
• Skaar, Johannes (2018). Energi - uten en tråd.
• Skaar, Johannes (2018). Fysikk og musikk.
• Skaar, Johannes (2018). Matematikk i musikk.
• Andersen, Elise Rønnevig; Bratberg, Øivind; Hellum, Mari Kjos; Hjelle, Ole Petter; Hussein, Bassam; Lie, Anne Helene Kveim; McNicol, John; Raklev, Are; Selboe, Tone; Skaar, Johannes & Stensaker, Inger G. (2017, 31. august). Landets beste forelesere svarer: Slik studerer du mest effektivt.  Aftenposten.
• Klingenberg, Mathias & Skaar, Johannes (2017, 13. februar). 100 milliarder bilder i sekundet fanger lys som går raskere enn seg selv. [Fagblad].  Teknisk ukeblad.
• Mauren, Arnfinn & Skaar, Johannes (2017, 01. januar). Magisk teknologi kan bety farvel til hacking. [Fagblad].  Aftenposten Vitenskap.
• Opheim, Aagot & Skaar, Johannes (2017, 11. januar). Vil gi ære, status og høyere lønn til de beste underviserne.  Adresseavisen.
• Sande, Anniken & Skaar, Johannes (2017, 27. januar). Her og nå: Dagens gjest. [Radio].  NRK P1.
• Skaar, Johannes (2017). Musikkens fysikk.
• Skaar, Johannes & Tollersrud, Emma (2017, 20. januar). Med lønnsøkning skal underviserne skinne.  Morgenbladet.
• Stensvold, Tore & Skaar, Johannes (2017, 13. oktober). Norwegian Tech Awards 2017 - WÄRTSILÄ. De lader ferge med 1,2 megawatt effekt - uten fysisk kontakt med fartøyet. [Fagblad].  Teknisk ukeblad.
• Sund, Steinar & Skaar, Johannes (2017, 27. september). Snart kan du lade med klærne. [Tidsskrift].  Aftenposten Vitenskap.
• Sævik, Bjørnar Torvholm; Folven, Erik; Jahre, Magnus & Skaar, Johannes (2017, 24. februar). Ein æra er omm. [Internett].  nrk.no.
• Bakken, Kjersti & Skaar, Johannes (2016, 20. september). Norgesglasset: "Lærer man egentlig noe av forelesninger, eller trenger studentene noe helt annet for å bli flinke?". [Radio].  NRK P1.
• Dirdal, Christopher Andrew; Hågenvik, Hans Olaf & Skaar, Johannes (2016). Higher order terms and origin dependence in metamaterial homogenization.
• Dirdal, Christopher Andrew; Hågenvik, Hans Olaf & Skaar, Johannes (2016). Permittivity, permeability, and the significance of the electrical quadrupole in metamaterials.
• Hågenvik, Hans Olaf; Dirdal, Christopher Andrew & Skaar, Johannes (2016). Homogenization of metamaterials: comparison and analysis.
• Indregard, Sigve & Skaar, Johannes (2016, 25. november). Til Mars med mikrobølgeovn.  Morgenbladet.
• Kleiven, David; Skjønsfjell, Eirik Torbjørn Bakken; Zontone, Federico; Chushkin, Yuriy; Skaar, Johannes & Breiby, Dag Werner (2016). Experimental and Numerical Studies for Improved Coherent Diffraction Phase Retrieval.
• Skaar, Johannes (2016). Kortforedrag om musikk og fysikk.
• Skaar, Johannes (2016). Magneter, metallrør og usynlighetskapper.
• Tollersrud, Emma & Skaar, Johannes (2016, 02. september). «Hvis vi ikke underviser, er det lett å ta elementære ting for gitt.».  Morgenbladet.
• Dirdal, Christopher Andrew & Skaar, Johannes (2015). Giving Freedom and Physical Meaning to the Effective Parameters of Metamaterials for all Frequencies.
• Hågenvik, Hans Olaf & Skaar, Johannes (2015). Laplace-Fourier analysis and instabilities of an active slab.
• Jegtvik, Karin & Skaar, Johannes (2015, 02. april). Er du vinneren av påskefjellet?. [Internett].  nrk.no.
• Ramsdal, Roar & Skaar, Johannes (2015, 18. mars). Her sendes 10 kilowatt trådløst. [Internett].  Teknisk ukeblad.
• Skaar, Johannes (2015). Hva er lys?.
• Skaar, Johannes (2015). Maxwells teori og Hertz' eksperiment – grunnlaget for moderne telekommunikasjon ble skapt for 150 år siden.
• Andreassen, Katrine; Skaar, Johannes; Løland, Anders & Rolén, Tage (2014, 11. februar). Finn ut om du er en sinke på ski. [Internett].  klikk.no.
• Brandslet, Steinar; Skaar, Johannes; Løland, Anders & Rolén, Tage (2014). Hvor fort går du på ski?. Aftenposten (morgenutg. : trykt utg.).  ISSN 0804-3116.
• Børringbo, Klaus & Skaar, Johannes (2014, 29. september). Trådløs strøm – snart er den her.  Aftenposten.
• Dalløkken, Per Erlien; Skaar, Johannes & Samset, Bjørn Hallvard (2014, 01. juli). «Metamaterialer» skal beskytte piloter mot laserangrep fra bakken. [Internett].  Teknisk ukeblad.
• Dirdal, Christopher Andrew & Skaar, Johannes (2014). Metamaterial responses beyond the Kramers-Kronig relations.
• Dirdal, Christopher Andrew & Skaar, Johannes (2014). Superposing Lorentzian functions towards engineering target responses. The 5th International Conference on Metamaterials, Photonic Crystals and Plasmonics Book of Abstracts.
• Dirdal, Christopher Andrew & Skaar, Johannes (2014). Superposing Lorentzian functions towards engineering target responses.
• Iversen, Marita Løvmo; Jansrud, Line & Skaar, Johannes (2014, 27. april). Går det an å gjøre noe usynlig? NRK Newton. [TV].  NRK 1.
• Schirber, Michael; Bugge, Audun Nystad; Sauge, Sebastien; Ghazali, Aina; Skaar, Johannes; Lydersen, Lars Vincent Van de Wiel & Makarov, Vadim (2014, 18. februar). Synopsis: Cyberattack by Breaking and Entering. [Internett].  APS Physics.
• Svendsen, Guro Kristin; Skaar, Johannes; Weman, Helge & Dupertuis, M.-A. (2014). Symmetries and optical transitions of hexagonal quantum dots in GaAs/AlGaAs nanowires.
• Brandslet, Steinar; Skaar, Johannes; Løland, Anders & Rolén, Tage (2013, 12. desember). Hvor fort går du på ski?. [Internett].  forsking.no.
• Brandslet, Steinar; Skaar, Johannes; Løland, Anders & Rolén, Tage (2013). Hvor fort går du på ski?. Gemini.  ISSN 0802-085X.  (2), s 6- 7
• Flæten, Sigurd Øygarden & Skaar, Johannes (2013, 05. desember). Laser kan bli fremtidens spionkamera. [Internett].  Teknisk ukeblad.
• Haugen, Vegard & Skaar, Johannes (2013). Døde av elektrosjokk med iPhone 5 i hånden. VG-Nett.
• Haugen, Vegard & Skaar, Johannes (2013, 15. juli). Døde av elektrosjokk med iPhone 5 i hånden. [Internett].  amobil.no.
• Lydersen, Lars Vincent Van de Wiel & Skaar, Johannes (2013). Kvantekryptografi. Fra Fysikkens Verden.  ISSN 0015-9247.  75(1), s 10
• Moe, Enok & Skaar, Johannes (2013). Rockheim forstyrrer flytrafikken på Værnes. Adresseavisen.  ISSN 0805-3804.
• Skaar, Johannes; Løland, Anders; Rolén, Tage & Kokkegård, Hanne (2013, 26. desember). Vild med tal? Tæl dig frem til, om du er hurtigst. [Internett].  dr.dk.
• Bugge, Audun Nystad; Sauge, Sebastien; Ghazali, Aina; Skaar, Johannes; Lydersen, Lars Vincent Van de Wiel & Makarov, Vadim (2012). Laser damage of photodiodes helps the eavesdropper.
• Grepstad, Jon Olav; Kaspar, Peter; Johansen, Ib-Rune; Skaar, Johannes; Sudbø, Aasmund & Solgaard, Olav (2012). Optical detection of single biomolecules using photonic-crystal membranes.
• Time, Jon Kåre & Skaar, Johannes (2012, 13. september). I bakvendtland der alt går an.  Morgenbladet.
• Time, Jon Kåre & Skaar, Johannes (2012, 06. september). Trollmannen fra Tyrifjord.  Morgenbladet.
• Christensen, Arnfinn & Skaar, Johannes (2011, 27. mai). Strøm uten støpsel. [Internett].  forskning.no.
• Giæver, Ole Peder; Liu, Qin; Makarov, Vadim & Skaar, Johannes (2011, 16. august). Norske forskere knekte koden. [Internett].  ABC nyheter.
• Grepstad, Jon Olav; Due-Hansen, Jon; Johansen, Ib-Rune; Borch, Morten; Kaspar, Peter; Furuberg, Liv; Skaar, Johannes; Sudbø, Aasmund Sveinung & Solgaard, Olav (2011). Umiddelbar diagnose i 2020.
• Grepstad, Jon Olav; Kaspar, Peter; Due-Hansen, Jon; Johansen, Ib-Rune; Borch, Morten; Furuberg, Liv; Skaar, Johannes; Sudbø, Aasmund Sveinung & Solgaard, Olav (2011). System for optical characterization of photonic crystal membranes - designed for biological sensing with single molecule sensitivity.
• Grepstad, Jon Olav & Skaar, Johannes (2011). Does evanescent gain exist?.
• Jemterud, Torkild & Skaar, Johannes (2011, 04. januar). Verdt å vite: Usynlighetskapper. [Radio].  NRK P2.
• Lee, Chris; Makarov, Vadim; Liu, Qin & Skaar, Johannes (2011, 15. november). Researchers show how to break quantum cryptography by faking quantum entanglement. [Internett].  Ars Technica.
• Liu, Qin; Gerhardt, Ilja; Makarov, Vadim; Skaar, Johannes; Lamas-linares, Antia; Scarani, Valerio & Kurtsiefer, Christian (2011). Implementation of an attack scheme on a practical QKD system.
• Liu, Qin; Makarov, Vadim & Skaar, Johannes (2011, 23. juni). Eavesdropper Steals Quantum Crypto Keys. [Internett].  InformationWeek.
• Liu, Qin; Makarov, Vadim & Skaar, Johannes (2011, 01. august). Eavesdropper demonstrates loophole in secure communications. [Internett].  Photonics Spectra.
• Liu, Qin; Makarov, Vadim & Skaar, Johannes (2011, 18. juni). First Exploit On Quantum Cryptography Confirmed. [Internett].  Slashdot.
• Liu, Qin; Makarov, Vadim & Skaar, Johannes (2011, 16. juni). Gjør kvantekryptografi enda sikrere. [Internett].  digi.no.
• Liu, Qin; Makarov, Vadim & Skaar, Johannes (2011, 19. juni). Hackers pioneros rompen criptosistema cuántico. [Internett].  ALT1040.
• Liu, Qin; Makarov, Vadim & Skaar, Johannes (2011, 17. juni). Hackers steal quantum code. [Internett].  Physics World.
• Liu, Qin; Makarov, Vadim & Skaar, Johannes (2011, 14. juni). Kryptografia kwantowa jest nie do złamania?. [Internett].  Gazeta.pl.
• Liu, Qin; Makarov, Vadim & Skaar, Johannes (2011, 20. juni). Quantum crypto felled by 'Perfect Eavesdropper' exploit. [Internett].  The Register.
• Liu, Qin; Makarov, Vadim & Skaar, Johannes (2011, 15. august). Scientists crack quantum cryptography. [Internett].  Computing.co.uk.

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