Experimental realization of a relativistic fluxon ratchet

Carapella, G.; Costabile, G.; Martucciello, Nadia; Cirillo, M.; Latempa, R.; Polcari, A.; Филатрелла, Г.

doi:10.1016/s0921-4534(02)01232-7

Cited by 22 publications

(19 citation statements)

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“…For sample G3, which is longer, we reach 12 GHz ( u = 0.91). Our normalized average velocity u is considerably larger than 0.22 [22] or 0.33 [9], reported recently for similar ratchet(-like) systems. The curve for sample C2 shows a negative dc voltage step, as expected for I inj1 = 470 µA > 0, see Fig.…”

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confidence: 62%

“…Instead, we construct an asymmetric periodic potential U(x 0 ), which is a function of the fluxon coordinate. In contrast to other JVRs [7,8,9,10,11,12], we construct U(x 0 ) using a single current injector. As we proposed earlier (see the last paragraph before Sec.…”

mentioning

confidence: 99%

“…Similar systems, but with magnetic field induced potential U(x 0 ), were already studied for the case of quasi-static deterministic and stochastic drive [7,8] and for deterministic high frequency drive [9]. Ratchetlike systems based on an asymmetry of the driver (rather than the potential) were also investigated [20,21,22].…”

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High-Efficiency Deterministic Josephson Vortex Ratchet

et al. 2005

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We investigate experimentally a Josephson vortex ratchet -a fluxon in an asymmetric periodic potential driven by a deterministic force with zero time average. The highly asymmetric periodic potential is created in an underdamped annular long Josephson junction by means of a current injector providing efficiency of the device up to 91%. We measured the ratchet effect for driving forces with different spectral content. For monochromatic high-frequency drive the rectified voltage becomes quantized. At high driving frequencies we also observe chaos, sub-harmonic dynamics and voltage reversal due to the inertial mass of a fluxon. The ratchet effect, i.e., the net unidirectional motion of a particle in a spatially asymmetric periodic potential in the presence of deterministic or stochastic forces with zero time average, received a lot of attention during the 20-th century. The second law of thermodynamics does not allow to extract useful work out of equilibrium thermal fluctuations, as was didactically demonstrated by Feynman [1]. Thus, the only way to produce useful work is to supply non-native fluctuations (usually colored noise), which is the basic principle of operation for any ratchet.Particularly during the last decade ratchets were receiving a lot of attention [2,3,4]. Several new implementations, in particular based on the motion of the Josephson phase in SQUIDs [5] or vortices in long Josephson junctions (LJJ) [6,7,8,9] or Josephson junction arrays (JJA) [10,11,12], were suggested and tested. The investigation of quantum ratchets [13,14,15], i.e., a quantum particle moving/tunneling quantum mechanically in an asymmetric potential, is a fascinating new field not very well developed up to now especially experimentally. Advantages of Josephson junction based ratchets are: (I) directed motion results in an average dc voltage which is easily detected experimentally; (II) Josephson junctions are very fast devices which can operate (capture and rectify noise) in a broad frequency range from dc to ∼ 100 GHz, thus capturing a lot of spectral energy; (III) by varying junction design and bath temperature both overdamped and underdamped regimes are accessible; and (IV) one can operate Josephson ratchets in the quantum regime [15].In this letter we investigate experimentally the deterministic underdamped Josephson vortex ratchet (JVR), in which a Josephson vortex (fluxon) moves along a LJJ. We implemented a novel, effective way to construct a strongly asymmetric potential by means of a current injector and systematically study a quasi-statically driven ratchet with different spectral content of the driver. For non-adiabatic drive we observe quantized rectification, voltage reversal, sub-harmonic, and chaotic dynamics. Our system can be described by the following perturbed sine-Gordon equation [6] φwhere φ is the Josephson phase, the curvilinear coordinate x along the LJJ and the time t are normalized to the Josephson penetration depth λ J and inverse plasma frequency ω −1 p , accordingly, α is the dimensionless damping pa...

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High-Efficiency Deterministic Josephson Vortex Ratchet

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“…La ecuación (2) aparece en varios contextos: en flujos relativistas con la ecuación de Klein-Gordon no lineal amortiguada [11], cuando φ(y) =…”

Section: Introductionunclassified

La Φ-ecuación de Tricomi

Castro

Gutiérrez

2018

ing.cienc

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ResumenEn este artículo se estudia una ecuación diferencial no lineal autónoma que modela el movimiento de un φ -péndulo amortiguado con forzamiento constante. En el caso disipativo se presentan dos resultados, por un lado, usando la aplicación de Poincaré y funciones de energía, se establece un criterio suficiente para determinar la existencia, unicidad y estabilidad asintótica de una solución periódica de segunda clase y por otro lado, se presenta un criterio con el que se estima analíticamente la cuenca de atracción de un equilibrio asintóticamente estable con ayuda del principio de invarianza de Lasalle. Mientras que en el caso conservativo se dan condiciones necesarias para que la imagen de la función periodo esté definida en un intervalo no acotado. Los resultados obtenidos en el caso disipativo son una generalización de los establecidos por Tricomi en el caso newtoniano.

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“…Apart from answering some fundamental questions, they can be immediately employed for the extraction of work out of nonequilibrium thermal fluctuations, for rectification of deterministic signals, or for particle separation [1][2][3][4]. Apart from the ratchets existing in nature [5], there are plenty of artificial ratchet implementations, in particular, based on nanostructured superconductors: Josephson vortex ratchets [6][7][8][9][10][11][12][13][14][15][16], SQUID ratchets [17][18][19][20][21][22][23] and Abrikosov vortex ratchets [24,25].…”

Section: Introductionmentioning

confidence: 99%

TunableφJosephson junction ratchet

et al. 2016

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We demonstrate experimentally the operation of a deterministic Josephson ratchet with tunable asymmetry. The ratchet is based on a ϕ Josephson junction with a ferromagnetic barrier operating in the underdamped regime. The system is probed also under the action of an additional dc current, which acts as a counter force trying to stop the ratchet. Under these conditions the ratchet works against the counter force, thus producing a non-zero output power. Finally, we estimate the efficiency of the ϕ Josephson junction ratchet.

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Experimental realization of a relativistic fluxon ratchet

Cited by 22 publications

References 9 publications

High-Efficiency Deterministic Josephson Vortex Ratchet

High-Efficiency Deterministic Josephson Vortex Ratchet

La Φ-ecuación de Tricomi

TunableφJosephson junction ratchet

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