Search results for " jun"
showing 10 items of 611 documents
EFFECTS OF COLORED NOISE IN SHORT OVERDAMPED JOSEPHSON JUNCTION
2008
We investigate the transient dynamics of a short overdamped Josephson junction with a periodic driving signal in the presence of colored noise. We analyze noise induced henomena, specifically resonant activation and noise enhanced stability. We find that the positions both of the minimum of RA and maximum of NES depend on the value of the noise correlation time tau_c. Moreover, in the range where RA is observed, we find a non-monotonic behavior of the mean switching time as a function of the correlation time tau_c.
GENERATION OF ENTANGLED STATES OF TWO DISTANT CAVITY MODES VIA JOSEPHSON JUNCTION BASED DEVICES
2007
We present a simple scheme for the preparation of entangled states of the e.m. modes of two spatially separated microwave cavities exploiting their interaction with two superconducting SQUID rings embedded within them. The scheme requires that the two SQUID qubits are initially prepared in an entangled state and the possibility of controlling both the coupling strengths and the interaction times. We also briefly discuss the importance of such a theoretical scheme in view of possible applications in the context of quantum computing and its experimental feasibility.
Decoherence in circuits of small Josephson junctions
2001
We discuss dephasing by the dissipative electromagnetic environment and by measurement in circuits consisting of small Josephson junctions. We present quantitative estimates and determine in which case the circuit might qualify as a quantum bit. Specifically, we analyse a three junction Cooper pair pump and propose a measurement to determine the decoherence time $\tau_\phi$.
Noise induced effects in overdamped Josephson junction in the presence of colored noise
2007
We analyze the role of the correlated fluctuations, with a correlation time τc, in the dynamics of an overdamped Josephson junction in the presence of a periodic driving signal.
Microwave nanobolometer based on proximity Josephson junctions
2014
We introduce a microwave bolometer aimed at high-quantum-efficiency detection of wave packet energy within the framework of circuit quantum electrodynamics, the ultimate goal being single microwave photon detection. We measure the differential thermal conductance between the detector and its heat bath, obtaining values as low as $5\phantom{\rule{4.pt}{0ex}}\text{fW}/\mathrm{K}$ at $50\phantom{\rule{4.pt}{0ex}}\text{mK}$. This is one tenth of the thermal conductance quantum and corresponds to a theoretical lower bound on noise-equivalent power of order ${10}^{\ensuremath{-}20}\phantom{\rule{4.pt}{0ex}}\text{W}/\sqrt{\text{Hz}}$ at $50\phantom{\rule{4.pt}{0ex}}\text{mK}$. By measuring the dif…
Electron–phonon interaction in a thin Al–Mn film
2006
Abstract Aluminum doped with manganese is an interesting novel material with applications in normal metal–insulator–superconductor (NIS) tunnel junction devices and transition-edge sensors at sub-Kelvin temperatures. We have studied the electron–phonon (e–p) coupling in a thin aluminum film doped with 1% manganese, with a measuring technique based on DC hot-electron effect. The electron temperature was measured with the help of symmetric normal metal–insulator–superconductor tunnel-junction pairs (SINIS-thermometers). Measurements show that the temperature dependence of the e–p interaction is not consistent with existing theories for disordered metals, but follows a higher power law.
One and two dimensional tunnel junction arrays in weak Coulomb blockade regime-absolute accuracy in thermometry
1999
We have investigated one and two dimensional (1D and 2D) arrays of tunnel junctions in partial Coulomb blockade regime. The absolute accuracy of the Coulomb blockade thermometer is influenced by the external impedance of the array, which is not the same in the different topologies of 1D and 2D arrays. We demonstrate, both by experiment and by theoretical calculations in simple geometries, that the 1D structures are better in this respect. Yet in both 1D and 2D, the influence of the environment can be made arbitrarily small by making the array sufficiently large.
Polarity and bioelectrical patterning in a linear chain of non-excitable cells
2020
Abstract Polarity in multicellular systems is influenced by bioelectrical signals because electric potentials can act as spatio-temporal patterns for other biochemical processes that eventually emerge as long-lasting biological outcomes. We study the role of the electric potential in establishing head-tail polarity for the case of a chain of non-excitable cells. This biophysical model incorporates both single-cell (membrane ion channels) and multicellular (intercellular gap junctions) characteristics. The results are presented in the form of a bioelectrical phase space that complements traditional biochemical approaches and provides qualitative insights for the case of anterior/posterior po…
Microwave-induced coupling of superconducting qubits
2008
We investigate the quantum dynamics of a system of two coupled superconducting qubits under microwave irradiation. We find that, with the qubits operated at the charge co-degeneracy point, the quantum evolution of the system can be described by a new effective Hamiltonian which has the form of two coupled qubits with tunable coupling between them. This Hamiltonian can be used for experimental tests on macroscopic entanglement and for implementing quantum gates.
Experimental Analysis of Passive Intermodulation at Waveguide Flange Bolted Connections
2007
[EN] In this paper, the generation of passive intermodulation at rectangular waveguide flange bolted connections is investigated. An exhaustive series of tests has been performed in order to provide understanding on the physics lying behind such a phenomenon. In particular, the intermodulation response of the system has been studied as a function of the applied torque to the flange screws. It has been found that, in some situations, the intermodulation response differs from its expected behavior. An interpretation of such discrepancies is given, and practical guidelines for the design of waveguide flanges free of passive intermodulation are provided as well.