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Josephson emission with frequency span 1–11 THz from small Bi2Sr2CaCu2O8+δ mesa structures
Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.ORCID-id: 0000-0003-4815-5856
Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.ORCID-id: 0000-0002-3131-8658
Antal upphovsmän: 22017 (Engelska)Ingår i: Nature Communications, E-ISSN 2041-1723, Vol. 8, artikel-id 1742Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Mesa structures made of Bi2Sr2CaCu2O8+δ high-temperature superconductor represent stacks of atomic scale intrinsic Josephson junctions. They can be used for generation of high-frequency electromagnetic waves. Here we analyze Josephson emission from small-but-high mesas (with a small area, but containing many stacked junctions). We have found strong evidence for tunable terahertz emission with a good efficacy in a record high-frequency span 1–11 THz, approaching the theoretical upper limit for this superconductor. Emission maxima correspond to in-phase cavity modes in the mesas, indicating coherent superradiant nature of the emission. We conclude that terahertz emission requires a threshold number of junctions N ~ 100. The threshold behavior is not present in the classical description of stacked Josephson junctions and suggests importance of laser-like cascade amplification of the photon number in the cavity. 

Ort, förlag, år, upplaga, sidor
2017. Vol. 8, artikel-id 1742
Nationell ämneskategori
Den kondenserade materiens fysik
Forskningsämne
fysik
Identifikatorer
URN: urn:nbn:se:su:diva-149974DOI: 10.1038/s41467-017-01888-4ISI: 000416229300028PubMedID: 29170380Scopus ID: 2-s2.0-85035045188OAI: oai:DiVA.org:su-149974DiVA, id: diva2:1169665
Forskningsfinansiär
Vetenskapsrådet, 621-2014-4314Stiftelsen för internationalisering av högre utbildning och forskning (STINT), IG2013-5453Tillgänglig från: 2017-12-29 Skapad: 2017-12-29 Senast uppdaterad: 2023-03-28Bibliografiskt granskad
Ingår i avhandling
1. Superradiant THz wave emission from arrays of Josephson junctions
Öppna denna publikation i ny flik eller fönster >>Superradiant THz wave emission from arrays of Josephson junctions
2020 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

High-power, continuous-wave, compact and tunable THz sources are needed for a large variety of applications. Development of power-efficient sources of electromagnetic radiation in the 0.1-10 THz range is a difficult technological problem, known as the “THz gap.” Josephson junctions allow creation of monochromatic THz sources with an inherently broad range of tunability. However, emission power from a single junction is too small. It can be amplified in a coherent superradiant manner by phase-locking of many junctions. In this case, the emission power should increase as a square of the number of phase-locked junctions.The aim of this thesis is to study a possibility of achieving coherent super-radiant emission with significant power and frequency tunability from Joseph-son junction arrays. Two types of devices are studied, based either on stacks (one-dimensional arrays) of intrinsic Josephson junctions naturally formed in single crystals of high-temperature cuprate superconductor Bi2Sr2CaCu2O8+x, or two-dimensional arrays of artificial low-temperature superconducting Nb/NbSi/Nb junctions. Micron-size junctions are fabricated using micro- and nanofabrication tools.The first chapter of this thesis describes the theory of Josephson junctions and how mutual coupling between Josephson junctions can lead to self-syn-chronization, facilitating the superradiant emission of electromagnetic radia-tion. The second chapter is focused on the technical aspects of this work, with detailed descriptions of sample fabrication and experimental techniques. The third chapter presents main results and discussion. It is demonstrated that de-vices based on high-Tc cuprates allow tunable emission in a very broad fre-quency range 1-11 THz. For low- Tc junction arrays synchronization of up to 9000 junctions is successfully achieved. It is argued that an unconventional traveling-waves mechanism facilitates the phase-locking of such huge arrays. The obtained results confirm a possibility of creation of high-power, continu-ous-wave, compact and tunable THz sources, based on arrays of Josephson junctions.

Ort, förlag, år, upplaga, sidor
Stockholm: Department of Physics, Stockholm University, 2020. s. 67
Nyckelord
Josephson junction, Superconductor, ThZ emission, high-Tc
Nationell ämneskategori
Fysik
Forskningsämne
fysik
Identifikatorer
urn:nbn:se:su:diva-181234 (URN)978-91-7911-178-6 (ISBN)978-91-7911-179-3 (ISBN)
Disputation
2020-09-09, sal FR4, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2020-08-17 Skapad: 2020-04-28 Senast uppdaterad: 2022-03-04Bibliografiskt granskad

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Borodianskyi, Evgenii A.Krasnov, Vladimir M.

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