Controllable plasma energy bands in a one-dimensional crystal of fractional Josephson vortices

Susanto, Hadi; Goldobin, E.; Koelle, D.; Kleiner, R.; Gils, Stephan A. van

doi:10.1103/physrevb.71.174510

Cited by 30 publications

(25 citation statements)

References 39 publications

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“…For instance, it has already been shown 4,28 that the frequency intervals where the electromagnetic JPWs can propagate form a band structure if a periodic superlattice of Josephson vortices is induced by an in-plane magnetic field in superconducting multilayers or a long 1D Josephson junction. This JPW photonic crystal, 4 with gaps of forbidden frequency ranges tuned by the in-plane magnetic field, is a much more controllable analog of both the band structure in 1D conductors and standard photonic crystals.…”

Section: Introductionmentioning

confidence: 99%

Controlled terahertz frequency response and transparency of Josephson chains and superconducting multilayers

et al. 2007

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A fundamental property of wave propagation is Anderson localization, which affects the transfer of information, energy, mass, and charge in disordered media. This localization can manifest itself via, e.g., the metal-insulator transition. We exactly map the behavior of a quantum particle moving in a potential with correlated disorder to the sub-terahertz wave propagation in either Josephson chains or superconducting multilayers. When the Josephson junction parameters vary randomly, the sub-THz electromagnetic waves cannot propagate through these Josephson structures due to localization. For parameter variations with long-range correlations, we predict sharp transitions from transparent to reflective frequency regions for Josephson plasma waves. With appropriate choices of the correlation function, frequency windows with targeted or designed transparencies for THz or sub-THz electromagnetic waves could be achieved. This could be useful for tailoring the electromagnetic wave spectrum of Josephson arrays within the THz frequency range, which is important for applications in physics, astronomy, chemistry, biology, and medicine.

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Section: Introductionmentioning

confidence: 99%

Controlled terahertz frequency response and transparency of Josephson chains and superconducting multilayers

et al. 2007

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“…Semifluxons are very interesting non-linear objects: they can form a variety of groundstates, 14,15,16,17,18 may flip, 9,11,19 rearrange 15 or get depinned 17,20,21 by a bias current, lead to half-integer zero-field steps 20,21,22 and have a characteristic eigenfrequency. 23 Huge arrays of fractional flux quanta 9,15,16,17 were realized and predicted to have a tunable plasmon band structure 24 which can be thought of as a plasmonic crystal similar to photonic crystals. Semifluxons are also promising candidates for storage devices in classical or quantum domain.…”

Section: Introductionmentioning

confidence: 99%

“…25 The variable κ can also be used as tuning parameter in some devices, e.g., to tune the plasmon band structure. 24 Second, due to low damping in Nb-AlO x -Nb LJJs one can study the dynamics of the fractional vortices. Exponentially low damping at T ≪ T c due to the energy gap also helps to build qubits with good decoherence figures.…”

Section: Introductionmentioning

confidence: 99%

Nonideal artificial phase discontinuity in long Josephson0−κjunctions

et al. 2005

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We investigate the creation of an arbitrary κ-discontinuity of the Josephson phase in a long NbAlOx-Nb Josephson junction (LJJ) using a pair of tiny current injectors, and study the formation of fractional vortices formed at this discontinuity. The current Iinj, flowing from one injector to the other, creates a phase discontinuity κ ∝ Iinj. The calibration of injectors is discussed in detail. The small but finite size of injectors leads to some deviations of the properties of such a 0-κ-LJJ from the properties of a LJJ with an ideal κ-discontinuity. These experimentally observed deviations in the dependence of the critical current on Iinj and magnetic field can be well reproduced by numerical simulation assuming a finite injector size. The physical origin of these deviations is discussed.

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“…The achieved π junction's Josephson penetration depth λ J as low as 160 µm at 2.11 K allows to fabricate long Josephson 0-π junctions of reasonable size and study half integer flux quanta (semifluxons) that appear at the 0-π boundaries [30,31,32] and have a size ∼ λ J . Reasonable λ J and low damping in such 0-π junctions may lead to useful classical [33,34] or quantum [35,36,37] circuits based on semifluxons.…”

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confidence: 99%

High quality ferromagnetic 0 and π Josephson tunnel junctions

Weides¹,

Kemmler

Goldobin

et al. 2006

Applied Physics Letters

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138

149

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We fabricated high quality Nb/Al2O3/Ni0.6Cu0.4/Nb superconductor-insulator-ferromagnetsuperconductor Josephson tunnel junctions. Depending on the thickness of the ferromagnetic Ni0.6Cu0.4 layer and on the ambient temperature, the junctions were in the 0 or π ground state. All junctions have homogeneous interfaces showing almost perfect Fraunhofer patterns. The Al2O3 tunnel barrier allows to achieve rather low damping, which is desired for many experiments especially in the quantum domain. The McCumber parameter βc increases exponentially with decreasing temperature and reaches βc ≈ 700 at T = 2.11 K. The critical current density in the π state was up to 5 A/cm 2 at T = 2.11 K, resulting in a Josephson penetration depth λJ as low as 160 µm. Experimentally determined junction parameters are well described by theory taking into account spin-flip scattering in the Ni0.6Cu0.4 layer and different transparencies of the interfaces. , which is self-biased and well decoupled from the environment, one needs to use high quality π JJs with high resistance (to avoid decoherence) and reasonably high critical current density j c (to have the Josephson energy E J ≫ k B T for junction sizes of few microns or below). High j c is also required to keep the Josephson plasma frequency ω p ∝ √ j c , which plays the role of an attempt frequency in the quantum tunneling problem, on the level of a few GHz.The concept of π JJs was introduced long ago[5, 6], but only recently superconductor-ferromagnet-superconductor (SFS) π JJs were realized [7,8]. Unfortunately SFS π JJs are highly overdamped and cannot be used for applications where low dissipation is required. The obvious way to decrease damping is to make a SFS-like tunnel junction, i.e. a superconductor-insulator-ferromagnet-superconductor (SIFS) junction. Due to the presence of the tunnel barrier the critical current I c in SIFS is lower than in SFS, but both the resistance R (at I I c ) and the I c R product are much higher. Moreover, the value of I c and R can be tuned by changing the thickness d I of the insulator (tunnel barrier).

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Controllable plasma energy bands in a one-dimensional crystal of fractional Josephson vortices

Cited by 30 publications

References 39 publications

Controlled terahertz frequency response and transparency of Josephson chains and superconducting multilayers

Controlled terahertz frequency response and transparency of Josephson chains and superconducting multilayers

Nonideal artificial phase discontinuity in long Josephson0−κjunctions

High quality ferromagnetic 0 and π Josephson tunnel junctions

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