Broadband detection of squeezed vacuum: A spectrum of quantum states
Fakultät für Physik, Universität Konstanz - D-78457 Konstanz, Germany
Accepted: 8 September 1998
We demonstrate the simultaneous quantum state reconstruction of the spectral modes of the light field emitted by a continuous-wave degenerate optical parametric amplifier. The scheme is based on broadband measurement of the quantum fluctuations of the electric-field quadratures and subsequent Fourier decomposition into spectral intervals. Applying the standard reconstruction algorithms to each bandwidth-limited quantum trajectory, a “spectrum" of density matrices and Wigner functions is obtained. The recorded states show a smooth transition from the squeezed vacuum to a vacuum state. In the time domain we evaluated the first-order correlation function of the squeezed output field, showing good agreement with theory.
PACS: 42.50.Ar – Photon statistics and coherence theory / 42.50.Dv – Nonclassical field states; squeezed, antibunched, and sub-Poissonian states; operational definitions of the phase of the field; phase measurements / 42.25.Kb – Coherence
© EDP Sciences, 1998