Search results for "Pi Josephson junction"
showing 10 items of 23 documents
Phase sticking in one-dimensional Josephson junction chains
2013
Published version of an article in the journal: Physical Review B - Condensed Matter and Materials Physics. Also available from the publisher at: http://dx.doi.org/10.1103/PhysRevB.88.104501 We studied current-voltage characteristics of long one-dimensional Josephson junction chains with Josephson energy much larger than charging energy, EJ EC. In this regime, typical I-V curves of the samples consist of a supercurrent-like branch at low-bias voltages followed by a voltage-independent chain current branch, Ichain at high bias. Our experiments showed that Ichain is not only voltage-independent but it is also practically temperature-independent up to T=0.7TC. We have successfully model the tr…
Switching times in long-overlap Josephson junctions subject to thermal fluctuations and non-Gaussian noise sources
2014
We investigate the superconducting lifetime of long current-biased Josephson junctions, in the presence of Gaussian and non-Gaussian noise sources. In particular, we analyze the dynamics of a Josephson junction as a function of the noise signal intensity, for different values of the parameters of the system and external driving currents. We find that the mean lifetime of the superconductive state is characterized by nonmonotonic behavior as a function of noise intensity, driving frequency and junction length. We observe that these nonmonotonic behaviours are connected with the dynamics of the junction phase string during the switching towards the resistive state. An important role is played…
Adiabatic transport of Cooper pairs in arrays of Josephson junctions
1999
We have developed a quantitative theory of Cooper pair pumping in gated one-dimensional arrays of Josephson junctions. The pumping accuracy is limited by quantum tunneling of Cooper pairs out of the propagating potential well and by direct supercurrent flow through the array. Both corrections decrease exponentially with the number N of junctions in the array, but give a serious limitation of accuracy for any practical array. The supercurrent at resonant gate voltages decreases with N only as sin(v/N)/N, where v is the Josephson phase difference across the array.
INFLUENCE OF LENGTH ON THE NOISE DELAYED SWITCHING OF LONG JOSEPHSON JUNCTIONS
2008
The transient dynamics of long overlap Josephson junctions in the frame of the sine-Gordon model with a white noise source is investigated. The effect of noise delayed decay is observed for the case of overdamped sine-Gordon equation. It is shown that this noise induced effect, in the range of small noise intensities, vanishes for junctions lengths greater than several Josephson penetration length.
THE ROLE OF NON-GAUSSIAN SOURCES IN THE TRANSIENT DYNAMICS OF LONG JOSEPHSON JUNCTIONS
2013
We analyze the effects of different non-Gaussian noise sources on the transient dynamics of an overdamped long Josephson junction. We find nonmonotonic behavior of the mean escape time as a function of the noise intensity and frequency of the external driving signal for all the noise sources investigated.
Interaction-free measurements with superconducting qubits
2008
An interaction-free measurement protocol is described for a quantum circuit consisting of a superconducting qubit and a read-out Josephson junction. By measuring the state of the qubit one can ascertain the presence of a current pulse through the circuit at a previous time without any energy exchange between the qubit and the pulse.
JOSEPHSON MESOJUNCTIONS AS DETECTORS OF LOW-INTENSITY QUANTIZED COHERENT FAR-INFRARED FIELDS
2000
We show that the quantum nature of a mesoscopic Josephson junction may be exploited for detecting low-intensity electromagnetic quantized fields. In particular we prove that intensity and phase of single-mode quantized coherent field may be reconstructed measuring amplitude and quantum noise of the first quantum Shapiro step occurring in the I-V characteristic of the ultrasmall Josephson junction.
Number theory implications on the physical properties of elementary cubic networks of Josephson junctions
2003
Number theory concepts are used to investigate the periodicity properties of the voltage vs applied flux curves of elementary cubic networks of Josephson junctions. It is found that equatorial gaps appearing on the unitary sphere, on which points representing the directions in space for which these curves show periodicity are collected, can be understood by means of Gauss condition on the sum of the squares of three integers.
Running-phase state in a Josephson washboard potential
2005
We investigate the dynamics of the phase variable of an ideal underdamped Josephson junction in switching current experiments. These experiments have provided the first evidence for macroscopic quantum tunneling in large Josephson junctions and are currently used for state read-out of superconducting qubits. We calculate the shape of the resulting macroscopic wavepacket and find that the propagation of the wavepacket long enough after a switching event leads to an average voltage increasing linearly with time.
Flux flow effects in very long Josephson junctions
2000
We report on measurements on very long, L ≃ 30λj, NbAlOxNb underdamped in-line junctions, on which we observed displaced linear slope (DLS) generated by the application of an external magnetic field. We study the behaviour of the branches as a function of the applied magnetic field in terms of both current amplitude and voltage position. The DLS is seen to shift rigidly towards higher voltages when increasing the field, spanning a region roughly centred around the Josephson plasma frequency. We discuss the behaviour of linear branches in terms of one dimensional flux-flow along the extended side of the junction, comparing our data with the results of numerical modeling; from these calculat…