Zero-point fluctuation and noise phenomena in Josephson junctions

Halima Giovanna Ahmad, D. Massarotti, Valentina Brosco +11 more

R. H. Koch, Dale J. Van Harlingen, John L. Clarke

The spectral density of the voltage noise has been measured in current-biased resistively shunted Josephson junctions in which quantum corrections to the noise are expected to be important. The experimental data are in excellent agreement with theoretical pretions, demonstrating clearly the contribution of zero-point fluctuations that are generated in the shunt at frequencies near the Josephson frequency and mixed down to the measurement frequency.

Jørn Bindslev Hansen

Bin Shao

To investigate the interaction of a mesoscopic Josephson junction with a single mode quantized electromagnetic field, the diagnonalizing process of the coupled system Hamiltonian was performed by using an unitary transformation. Zero? point energy and zero? point fluctuation of the coupled system were shown. For the ground state of the coupled system, the quantum fluctuations of the flux and charge operators in the field and junction subsystems can exhibit smaller quantum noise than the zero point fluctuations of the individual subsystems. Thus, when the coupled system is in its lowest energy state, which means that no radiation appear, the two subsystems exhibit nonclassical behavior.

Wang Wenguo, MANFRED L. RISTIG

Rene K. Lindell, Mika A. Sillanpää, Tero Tapio Heikkilä +3 more