Antibunched Photons Emitted by a dc-Biased Josephson Junction.

We show experimentally that a dc biased Josephson junction in series with a high-enough-impedance microwave resonator emits antibunched photons. Our resonator is made of a simple microfabricated spiral coil that resonates at 4.4 GHz and reaches a 1.

Emission of Nonclassical Radiation by Inelastic Cooper Pair Tunneling.

We show that a properly dc-biased Josephson junction in series with two microwave resonators of different frequencies emits photon pairs in the resonators. By measuring auto- and intercorrelations of the power leaking out of the resonators, we demonstrate two-mode amplitude squeezing below the classical limit. This nonclassical microwave light emission is found to be in quantitative agreement with our theoretical predictions, up to an emission rate of 2 billion photon pairs per second.

Observation of half-quantum defects in superfluid 3He-B.

In the course of high-precision measurements of the relation between the superflow current J through a weak link in 3He-B and the difference in order parameter phase between each side of the link phi in a flexible wall Helmholtz resonator equipped with a rotation pickup loop, we have observed the signature of a stable textural defect that sustains a change of the phase by pi across it. "Cosmiclike" solitons, proposed by Salomaa and Volovik and hitherto thought unstable, can constitute such a defect.

Observation of the ideal Josephson effect in superfluid 4He.

Superfluids and superconductors are the only states of condensed matter that can be described by a single wavefunction, with a coherent quantum phase Phi. The mass flow in a superfluid can be described by classical hydrodynamics for small flow velocity, but above a critical velocity, quantized vortices are created and the classical picture breaks down. This can be observed for a superfluid flowing through a microscopic aperture when the mass flow is measured as a function of the phase difference across the aperture; the curve resembles a hysteretic sawtooth where each jump corresponds to the creation of a vortex.