Observation of two-mode squeezing in the microwave frequency domain.
Continuous variable entanglement between two modes of a radiation field is usually studied at optical frequencies. Here we demonstrate experiments that show the entanglement between microwave photons of different energy in a broadband squeezed beam. We use a Josephson parametric amplifier to generate the two-mode correlated state 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, which is in good agreement with the one expected for a two-mode squeezed state.
Department of Physics, ETH Zürich, CH-8093, Zürich, Switzerland.
C
C
Eichler
D
D
Bozyigit
C
C
Lang
M
M
Baur
L
L
Steffen
J M
JM
Fink
S
S
Filipp
A
A
Wallraff