Complementary Josephson Junction circuits

Terzioglu, E.; Gupta, Deepnarayan; Beasley, M. R.

doi:10.1109/77.622207

Cited by 11 publications

(9 citation statements)

References 6 publications

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“…As predicted more than 30 years ago [1], Josephson junctions can have a phase drop of π in the ground state. Such π junctions are now intensively investigated, as they have a great potential for applications in a broad range of devices ranging from classical digital circuits [2,3,4,5] to quantum bits [6,7,8,9]. Nowadays, π Josephson junctions can be fabricated by various technologies, including junctions with a ferromagnetic barrier [10,11,12,13,14,15,16,17,18], quantum dot junctions [19,20,21] and nonequilibrium superconductor-normal metal-superconductor Josephson junctions [22,23,24] In the simplest case the supercurrent density j s across the junctions is given by the first Josephson relation…”

Section: Introductionmentioning

confidence: 99%

Visualizing supercurrents in ferromagnetic Josephson junctions with various arrangements of 0 andπsegments

et al. 2010

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Josephson junctions with ferromagnetic barrier can have positive or negative critical current depending on the thickness d F of the ferromagnetic layer. Accordingly, the Josephson phase in the ground state is equal to 0 (a conventional or 0 junction) or to π (π junction). When 0 and π segments are joined to form a "0-π junction", spontaneous supercurrents around the 0-π boundary can appear. Here we report on the visualization of supercurrents in superconductor-insulatorferromagnet-superconductor (SIFS) junctions by low-temperature scanning electron microscopy (LTSEM). We discuss data for rectangular 0, π, 0-π, 0-π-0 and 20 × (0-π-) junctions, disk-shaped junctions where the 0-π boundary forms a ring, and an annular junction with two 0-π boundaries.Within each 0 or π segment the critical current density is fairly homogeneous, as indicated both by measurements of the magnetic field dependence of the critical current and by LTSEM. The π parts have critical current densities j π c up to 35 A/cm 2 at T = 4.2 K, which is a record value for SIFS junctions with a NiCu F-layer so far. We also demonstrate that SIFS technology is capable to produce Josephson devices with a unique topology of the 0-π boundary.

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Section: Introductionmentioning

confidence: 99%

Visualizing supercurrents in ferromagnetic Josephson junctions with various arrangements of 0 andπsegments

et al. 2010

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“…The stability of the stationary solution µ 0 (x) can be analyzed with the help of the eigenmodes of the sine-Gordon equation (2). To find these eigenmodes we insert the ansatz…”

Section: Eigenmodesmentioning

confidence: 99%

“…into the sine-Gordon equation (2) and linearize it, assuming |ψ(x)| ≪ 1. Since µ 0 (x) solves the stationary sine-Gordon equation, we obtain the Schrödinger equation…”

Section: Eigenmodesmentioning

confidence: 99%

Theory of fractional vortex escape in a long Josephson junction

et al. 2009

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We consider a fractional Josephson vortex in an infinitely long 0-Josephson junction. A uniform bias current applied to the junction exerts a Lorentz force acting on a vortex. When the bias current becomes equal to the critical ͑or depinning͒ current, the Lorentz force tears away an integer fluxon and the junction switches to the resistive state. In the presence of thermal and quantum fluctuations this escape process takes place with finite probability already at subcritical values of the bias current. We analyze the escape of a fractional vortex by mapping the Josephson phase dynamics to the dynamics of a single particle in a metastable potential and derive the effective parameters of this potential. This allows us to predict the behavior of the escape rate as a function of the topological charge of the vortex.

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“…These junctions may be used in electronic circuits, e.g., in JJ flux qubits with low decoherence, 4 self-biased rapid single flux quantum digital circuits, 5 or complementary logic. 6 If the current-phase relation of a JJ has the usual form J͑͒ = J C sin͑͒ the ground state = 0 is realized for J C Ͼ 0 and the ground state = for J C Ͻ 0. The last condition may be satisfied in the case of a ferromagnetic barrier.…”

Section: Introductionmentioning

confidence: 99%

Ferromagnetic Josephson junctions with steplike interface transparency

et al. 2009

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Within the framework of the quasiclassical Usadel equations we study the Josephson effect in superconductor-insulator-ferromagnet-superconductor ͑SIFS͒ and SIFNS ͑N is a normal metal͒ structures with a steplike transparency of the FS or NS interface. At certain parameters the steplike transparency leads to the formation of a region, where the critical current-density distribution J C ͑y͒ along the junction exhibits a damped oscillation with a sign change. This results in the formation of a 0-nanojunction with the characteristic length of 0 and regions of the order of the coherence length F for SIFS and N for SIFNS junctions, respectively. Using several transparency steps one can create an array of nanojunctions. Such structures exhibit an unusual behavior in an external magnetic field H. The total critical current grows with increasing H up to a certain value, which depends on the size of a single nanojunction, and has multiperiodic oscillations in the case of an array.

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Complementary Josephson Junction circuits

Cited by 11 publications

References 6 publications

Visualizing supercurrents in ferromagnetic Josephson junctions with various arrangements of 0 andπsegments

Visualizing supercurrents in ferromagnetic Josephson junctions with various arrangements of 0 andπsegments

Theory of fractional vortex escape in a long Josephson junction

Ferromagnetic Josephson junctions with steplike interface transparency

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