Superconductor–insulator transition in a single Josephson junction (original) (raw)
Related papers
Theory of superconductor-insulator transition in single Josephson junctions
Physical Review B
A non-band theory is developed to describe the superconductor-insulator (SI) transtition in resistively shunted, single Josephson junctions. The I−VI-VI−V characteristic is formulated by a Landauer-like formula and evaluated by the path-integral transfer-matrix method. The result is consistent with the recent experiments at around 80 mKmKmK. However, the insulator phase shrinks with decreasing temperature indicating that the single Josephson junction becomes all superconducting at absolute zero temperature, as long as dissipation is present. Comment: 4 pages, 3 figures
Superconducting-insulator transition in disordered Josephson junctions networks
The European Physical Journal B, 2013
The superconducting-insulator transition is simulated in disordered networks of Josephson junctions with thermally activated Arrhenius-like resistive shunt. By solving the conductance matrix of the network, the transition is reproduced in different experimental conditions by tuning thickness, charge density and disorder degree. In particular, on increasing fluctuations of the parameters entering the Josephson coupling and the Coulomb energy of the junctions, the transition occurs for decreasing values of the critical temperature Tc and increasing values of the activation temperature To. The results of the simulation compare well with recent experiments where the mesoscopic fluctuations of the phase have been suggested as the mechanism underlying the phenomenon of emergent granularity in otherwise homogeneous films. The proposed approach is compared with the results obtained on TiN films and nanopatterned arrays of weak-links, where the superconductor-insulator transition is directly stimulated. arXiv: 1304.1911v1 [cond-mat.supr-con]
A Superconductor-Insulator Transition in a One-Dimensional Array of Josephson Junctions
Journal of Low Temperature Physics, 2000
We consider a one-dimensional Josephson junction array, in the regime where the junction charging energy is much greater than the charging energy of the superconducting islands. In this regime we critically reexamine the continuum limit description and establish the relationship between parameters of the array and the ones of the resulting sine-Gordon model. The later model is formulated in terms of quasi-charge. We argue that despite arguments to the contrary in the literature, such quasi-charge sine-Gordon description remains valid in the vicinity of the phase transition between the insulating and the superconducting phases. We also discuss the effects of random background charges, which are always present in experimental realizations of such arrays.
Quantum fluctuations and dissipative phase transition in one-dimensional Josephson junction arrays
Physica E: Low-dimensional Systems and Nanostructures, 2003
ABSTRACT We studied superconductor–insulator transition in one-dimensional arrays of small Josephson junctions in which each junction was shunted by ohmic resistor. The I–V characteristics changed from Coulomb-blockade type behavior to Josephson-like one with decreasing shunt resistance RS, even when the Josephson coupling energy EJ was much smaller than the charging energy EC(≡e2/C, C:junctioncapacitance). The critical value of RS was close to RQ(≡6.45kΩ) for EJ/EC smaller than unity. This agrees with theoretical predictions for dissipation-driven phase transitions in this system.
Superconducting and insulating behavior in one-dimensional Josephson junction arrays
Experiments on one-dimensional small capacitance Josephson Junction arrays are described. The arrays have a junction capacitance that is much larger than the stray capacitance of the electrodes, which we argue is important for observation of Coulomb blockade. The Josephson energy can be tuned in situ and an evolution from Josephson-like to Coulomb blockade behavior is observed. This evolution can be described as a superconducting to insulating, quantum phase transition. In the Coulomb blockade state, hysteretic current-voltage characteristics are described by a dynamic model which is dual to the resistively shunted junction model of classical Josephson junctions.
Dissipation and quantum phase transitions of a pair of Josephson junctions
Physical Review B, 2003
A model system consisting of a mesoscopic superconducting grain coupled by Josephson junctions to two macroscopic superconducting electrodes is studied. We focus on the effects of ohmic dissipation caused by resistive shunts and superconducting-normal charge relaxation within the grain. As the temperature is lowered, the behavior crosses over from uncoupled Josephson junctions, similar to situations analyzed previously, to strongly interacting junctions. The crossover temperature is related to the energy-level spacing of the grain and is of the order of the inverse escape time from the grain. In the limit of zero temperature, the two-junction system exhibits five distinct quantum phases, including a novel superconducting state with localized Cooper pairs on the grain but phase coherence between the leads due to Cooper pair cotunneling processes. In contrast to a single junction, the transition from the fully superconducting to fully normal phases is found to be controlled by an intermediate coupling fixed point whose critical exponents vary continuously as the resistances are changed. The model is analyzed via two component sine-Gordon models and related Coulomb gases that provide effective low temperature descriptions in both the weak and the strong Josephson coupling limits. The complicated phase diagram is consistent with symmetries of the two component sine-Gordon models, which include weak to strong coupling duality and permutation triality. Experimental consequences of the results and potential implications for superconductor to normal transitions in thin wires and films are discussed briefly.
Physical review. B, Condensed matter, 1995
We have studied the superconductor-insulator (Sl) phase transition for two-dimensional (2D) arrays of small Josephson junctions in a weak magnetic field. The data were analyzed within the context of the theory of the magnetic-field-tuned SI transition in 20 superconductors. We show resistance scaling curves over several orders of magnitude for the 20 arrays. The critical exponent zz is determined to be 1.05, in good agreement with the theory. Moreover, the transverse (Hall) resistance at the critical field is found to be very small in comparison to the longitudinal resistance.
npj Quantum Information, 2022
Non-equilibrium quasiparticles are possible sources for decoherence in superconducting qubits because they can lead to energy decay or dephasing upon tunneling across Josephson junctions (JJs). Here, we investigate the impact of the intrinsic properties of two-dimensional transmon qubits on quasiparticle tunneling (QPT) and discuss how we can use quasiparticle dynamics to gain critical information about the quality of JJ barrier. We find the tunneling rate of the non-equilibrium quasiparticles to be sensitive to the choice of the shunting capacitor material and their geometry in qubits. In some devices, we observe an anomalous temperature dependence of the QPT rate below 100 mK that deviates from a constant background associated with non-equilibrium quasiparticles. We speculate that this behavior is caused by high transmission sites/defects within the oxide barriers of the JJs, leading to spatially localized subgap states. We model this by assuming that such defects generate regions with a smaller effective gap. Our results present a unique in situ characterization tool to assess the uniformity of tunnel barriers in qubit junctions and shed light on how quasiparticles can interact with various elements of the qubit circuit.
Direct Measurement of the Josephson Supercurrent in an Ultrasmall Josephson Junction
Physical Review Letters, 2001
We have measured the supercurrent flowing through a nonhysteretic, ultrasmall, voltage-biased Josephson junction. In contrast with experiments performed so far on hysteretic Josephson junctions, we find a supercurrent peak whose maximum I s max increases as the temperature T decreases. The asymptotic T 0 value of I s max agrees with the junction Ambegaokar-Baratoff critical current, as predicted by theory.
Journal of Superconductivity and Novel Magnetism, 2013
Coherent passage of Cooper pairs in a Josephson junction (JJ) above the liquid nitrogen temperature has been the first impressive revolutionary effect induced by high critical temperature superconductors (HTS) in the domain of the study of Josephson effect (JE). But this has been only the start. A d-wave order parameter has lead to significant novel insights in the physics of the JE turning into a device the notion of a π-junction. Spontaneous currents in a frustrated geometry, Andreev bound states, long-range proximity effect have rapidly become standard terms in the study of the JE, standing as a reference bench for conventional systems based on low critical temperature superconductors (LTS) and inspiring analogies for junctions based on novel F. Tafuri ( ) · L. Longobardi · G. Rotoli