Current-voltage characteristics of nanoampere Josephson junctions

Ono, Ronald H.; Cromar, M. W.; Kautz, Richard L.; Soulen, R. J.; Colwell, J. H.; Fogle, William E.

doi:10.1109/tmag.1987.1064932

Cited by 28 publications

(9 citation statements)

References 11 publications

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“…Their coexistence in the same I-V is therefore unusual [28][29][30] and can be only understood with a finer analysis of the devices dynamics. We included in the RSJ model an additional quality factor Q 1 in order to take into account the contribution of the circuit the junction is embedded into.…”

Section: I-v Curves Of Unconventional Junctionsmentioning

confidence: 99%

What happens in Josephson junctions at high critical current densities

Massarotti¹,

Stornaiuolo²,

Lucignano³

et al. 2017

Low Temperature Physics

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The impressive advances in material science and nanotechnology are more and more promoting the use of exotic barriers and/or superconductors, thus paving the way to new families of Josephson junctions. Semiconducting, ferromagnetic, topological insulator and graphene barriers are leading to unconventional and anomalous aspects of the Josephson coupling, which might be useful to respond to some issues on key problems of solid state physics. However, the complexity of the layout and of the competing physical processes occurring in the junctions is posing novel questions on the interpretation of their phenomenology. We classify some significant behaviors of hybrid and unconventional junctions in terms of their first imprinting, i.e. current-voltage curves, and propose a phenomenological approach to describe some features of junctions characterized by relatively high critical current densities J c . Accurate arguments on the distribution of switching currents will provide quantitative criteria to understand physical processes occurring in high-J c junctions. These notions are universal and apply to all kinds of junctions.

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Section: I-v Curves Of Unconventional Junctionsmentioning

confidence: 99%

What happens in Josephson junctions at high critical current densities

Massarotti¹,

Stornaiuolo²,

Lucignano³

et al. 2017

Low Temperature Physics

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“…For small currents, we observe a linearV(I), which we characterize by R 0 , the differential resistance at I = 0. This new feature is now recognized as typical of small-geometric-capacitance, large-R,, junctions [lansiti, et al, 1987a, 1987bOno, et al, 1987;Martinis and Kautz, 1989], and, as discussed in section 5.2, it has profound implications for potential models of the physics of these samples. In particular, the co-existence in the IVC of hysteresis and phase evolution on the low-voltage branch is incompatible with the standard RCSJ model, where the Josephson channel is shunted by a capacitor and a frequency-independent resistor.…”

Section: Current-voltage Characteristics (Ivcs)mentioning

confidence: 99%

“…(a): L-R-C combination used by Ono, et al [1987]. ( Ambegaokar and Halperin [1969] for junctions with Q = 0.…”

Section: Romentioning

confidence: 99%

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Effect of Leads and Quantum Fluctuations in Small Superconducting Tunnel Junctions

Johnson¹

1990

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“…Therefore, an interesting model in the context of qubit detectors is the Josephson junction shunted by a series RC circuit, which has the property of overdamped phase dynamics at high frequencies, and underdamped dynamics at low frequencies. This model has been studied by several authors 8,9,10,11,12 . Kautz and Martinis showed that bistability is possible in this model, with one state characterized by "phase diffusion" where the phase is thermally kicked between minima of the potential, and the other state is that of a free running phase.…”

mentioning

confidence: 99%

Phase space topology of a switching current detector

et al. 2006

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We examine in theory and by numerical simulation, the dynamic process of switching from a zero voltage to a finite voltage state in a Josephson junction circuit. The theoretical model describes small capacitance Josephson junctions which are overdamped at high frequencies, and can be applied to detection of the quantum state of a qubit circuit. We show that the speed and fidelity of the readout are strongly influenced by the topology of the phase space attractors. The readout will be close to optimal when choosing the circuit parameters so as to avoid having an unstable limiting cycle which separates the two basins of attraction.One of the unique and exciting characteristics of quantum bits based on Josephson junction circuits (as opposed to quantum systems like atoms or nuclear spins) is the ability to engineer the system for optimal performance with regard to decoherence and readout efficiency. With Josephson junction circuits we have electrical access to the Hamiltonian of a quantum system described by two conjugate circuit variables. External current sources or voltage sources can be used to change potential and kinetic energies in the Hamiltonian of the quantum circuit 1 . This fact allows one to design a fast and reliable readout.The quantum dynamics of Josephson junction circuits is intensively studied by several groups around the world today. Many different circuits and measurement schemes have been proposed and implemented in experiments which prepare, evolve, and read out the quantum state of the circuit 2,3,4,5,6 . One of the most successful readout methods used this far is based on the switching of a Josephson junction from the zero voltage state to the finite voltage state. In this letter we analyze this switching process in some detail, focusing on the reliability of the detection method in the presence of external noise. We show that the existence of an unstable limiting cycle in the phase space dynamics of the Josephson junction leads to late retrapping (long measurement time) and false switching events, and that such an unstable cycle can be avoided with proper choice of parameters, while maintaining the desired overdamped phase dynamics.The switching current detector works on the principle that the quantum states one wants to differentiate have different critical currents I 0n = max[dE n /dφ], where E n is the energy of eigenstate n, and φ is the external phase of the circuit, which can be changed by application of an external current. Restricting ourselves to the two lowest energy states of the circuit (a qubit) we quickly ramp the current to a value I p , where I 00 > I p > I 01 . The circuit will evolve differently, depending on whether it is in state 0 or in state 1. If the qubit is in state 0, the circuit will not switch, meaning that it remains in the zero voltage state where the phase is trapped in a local minimum of the potential E 0 (φ). If the qubit is in state 1, it will switch, meaning that the phase escapes from this minimum, and evolves to a "free running" state with finite voltag...

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Current-voltage characteristics of nanoampere Josephson junctions

Cited by 28 publications

References 11 publications

What happens in Josephson junctions at high critical current densities

What happens in Josephson junctions at high critical current densities

Effect of Leads and Quantum Fluctuations in Small Superconducting Tunnel Junctions

Phase space topology of a switching current detector

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