Photon State Tomography for Two-Mode Correlated Itinerant Microwave Fields

Understand

Continuous variable entanglement between two modes of a radiation field is usually studied at optical frequencies.

• As an important step towards the observation of entanglement between propagating microwave photons we demonstrate the experimental state reconstruction of two field modes in the microwave domain.
• In particular, we generate two-mode correlated states with a Josephson parametric amplifier and detect all four quadrature components simultaneously in a two-channel heterodyne setup using amplitude detectors.
• Analyzing two-dimensional phase space histograms for all possible pairs of quadratures allows us to determine the full covariance matrix and reconstruct the four-dimensional Wigner function.