Current-Voltage Characteristics of Small Josephson Tunnel Junctions

Buckner, S.A.; Chen, J.T.; Langenberg, D. N.

doi:10.1103/physrevlett.25.738

Cited by 25 publications

(5 citation statements)

References 9 publications

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“…This effect was previously observed in ultra-small planar junctions and is well documented [15,18,19]. Furthermore, we confirm that this effect stems from Josephson tunneling by measuring the response of the junction in the presence of microwave fields with frequency f = 15.0 GHz, fed into a cylindrical cavity containing the STM by a semi-rigid coaxial cable antenna [20].…”

supporting

confidence: 58%

“…We have shown that the tunneling characteristics obtained in this experiment are in good agreement with the model of fluctuation-dominated Josephson tunneling. While the fluctuation-dominated dc Josephson effect has been observed previously in ultrasmall planar junctions [15,18,19], this is to our knowledge the first observation of the corresponding ac effect in the presence of microwave fields. We expect that a Josephson STM will prove useful as a probe of the SC pair amplitude on length scales of the order of the coherence length in high-T c materials.…”

mentioning

confidence: 78%

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Fluctuation Dominated Josephson Tunneling with a Scanning Tunneling Microscope

2001

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We demonstrate Josephson tunneling in vacuum tunnel junctions formed between a superconducting scanning tunneling microscope tip and a Pb film, for junction resistances in the range 50-300 kΩ. We show that the superconducting phase dynamics is dominated by thermal fluctuations, and that the Josephson current appears as a peak centered at small finite voltage. In the presence of microwave fields (f = 15.0 GHz) the peak decreases in magnitude and shifts to higher voltages with increasing rf power, in agreement with theory. 07.79. Cz, 74.40.+k, 74.50.+r Scanning tunneling microscopy (STM) has been extensively used in the study of high-T c superconductors (HTSC), providing a spectroscopic tool with unparalleled energy and spatial resolution. Yet, while superconducting tips have been demonstrated in the past [1] all STM studies so far have been performed using normal-metal tips, thus probing only the single-particle excitation spectrum, the gap structure which is a consequence of superconductivity, but not the superconducting (SC) ground state itself. Results from STM measurements of HTSC show excitation gaps in situations where superconductivity is believed to be absent (pseudo-gap), such as in vortex cores [2] and above T c in underdoped samples [3], as well as inhomogenieties in the gap structure in reportedly high quality BiSrCaCuO crystals [4]. These results, due to the nature of the measurements, do not remove the ambiguity with respect to the existence of a finite SC pair amplitude in the situations studied.

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supporting

confidence: 58%

mentioning

confidence: 78%

Fluctuation Dominated Josephson Tunneling with a Scanning Tunneling Microscope

2001

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“…For λ = 0, the classical Smoluchowski equation has been used to study properties of shunted Josephson junctions, such as the current-voltage characteristics [37,38]. These theoretical results have been successfully verified in a number of experiments [39][40][41], confirming the basic assumptions of the model. The stationary solution of the quantum Smoluchowski equation (3), with periodic boundary conditions, and V (φ) = V (φ + L), can be written as [42],…”

Section: Experimental Verification In Driven Josephsonmentioning

confidence: 59%

Quantum fluctuation theorems in the strong damping limit

Deffner¹,

Brunner²,

Lutz³

2011

EPL

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PACS 05.40.-a -Fluctuation phenomena in statistical physics PACS 03.65.Yz -Decoherence in quantum mechanicsAbstract. -We consider a driven quantum particle in the strong friction regime described by the quantum Smoluchowski equation. We derive Crooks and Jarzynski type relations for the reduced quantum system by properly generalizing the entropy production to take into account the nonGibbsian character of the equilibrium distribution. In the case of a nonequilibrium steady state, we obtain a quantum version of the Hatano-Sasa relation. We, further, propose an experiment with driven Josephson junctions that would allow to investigate nonequilibrium entropy fluctuations in overdamped quantum systems.Thermodynamic processes at the nanoscale are governed by both thermal and quantum fluctuations. It has lately been recognized that for classical nanosystems the second law of thermodynamics has to be generalized in order to include effects induced by thermal fluctuations. The latter are usually vanishingly small in macroscopic systems and are, therefore, neglected in the traditional formulation of thermodynamics [1]. These generalizations of the second law take the form of fluctuation theorems that quantify the occurrence of negative fluctuations of quantities like work, heat and entropy [2,3]. A remarkable property of these new thermodynamic identities is their general validity arbitrarily far from equilibrium. An important example of a fluctuation theorem is the one derived by Crooks [4]: it relates the probability distributions of work, ρ F (W ) and ρ R (W ), along forward and reversed transformations of a system according to,Here ∆F is the free energy difference between final and initial states. Equation (1) indicates that large negative work fluctuations are exponentially suppressed and, hence, not observable in macroscopic systems. In its integrated form, the Crooks relation reduces to an equality previously obtained by Jarzynski [5], connecting the equilibrium free energy difference ∆F to the nonequilibrium work W via,In the above equation, the average ... is taken over the forward work distribution. It is essential to realize that Eqs. (1) and (2) In this paper, we derive quantum generalizations of the classical Crooks and Jarzynski relations, Eqs. (1) and (2), in the strong friction regime. Previous studies on isolated or weakly coupled quantum systems can be found in Refs. [14][15][16][17], while an extension to the strongly coupled regime has been recently put forward in Ref. [18]. In the following, we use the quantum generalization of the Smoluchowski equation to treat both thermal and quantum fluctuations. Using the Onsager-Machlup path-integral representation, we show that the free energy difference for a driven quantum system can be obtained from its reduced semiclassical density operator. We, moreover, propose an experiment involving a driven Josephson junction that would allow to test our predictions.Quantum Smoluchowski equation. -In the limit of high friction, the off-diagonal matrix elements x|ρ(t)...

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“…Extended negative-resistance region on the I-V curves of very small area SIS tunnel junctions has been observed by Buckner, Chen and Langenberg [44]. This type of I-V characteristics has been analyzed by using the resistance-shunted model with a capacitive load [39,45].…”

Section: Performance Limit Of Sis Mixersmentioning

confidence: 94%

Conversion gain in mm-wave quasiparticle heterodyne mixers

Shen

Richards

Harris

et al. 1980

Applied Physics Letters

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We report the observation of heterodyne mixing in superconductor-insulator-superconductor tunnel junctions with significant conversion gain and with a noise temperature comparable to the photon noise limit. (Double sideband L−1=1.400.14, TM≲1.5 K at 36 GHz.) The mixing arises from the strong nonlinearity in the quasiparticle tunneling currents at voltages comparable to the full energy gap. Gain is observed when the onset of quasiparticle current is sufficiently sharp that quantum effects are important. The observed gain is in good quantitative agreement with calculations based on the work of Tucker. It should make possible the construction of photon-noise-limited microwave heterodyne receivers.

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Current-Voltage Characteristics of Small Josephson Tunnel Junctions

Abstract: A stable dc supercurrent with an extended negative-resistance region has been observed in the I-V characteristics of very small Josephson tunnel junctions. This supercurrent and its response to external noise are in accord with recent theoretical predictions of Ivanchenko and Zil'berman.

Cited by 25 publications

References 9 publications

Fluctuation Dominated Josephson Tunneling with a Scanning Tunneling Microscope

Fluctuation Dominated Josephson Tunneling with a Scanning Tunneling Microscope

Quantum fluctuation theorems in the strong damping limit

Conversion gain in mm-wave quasiparticle heterodyne mixers

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