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キーワード:
Quantum Physics, quant-ph
要旨:
Continuous-wave (cw) squeezed vacuum states of light have applications in
sensing, metrology and secure communication. In recent decades their efficient
generation has been based on parametric down-conversion, which requires pumping
by externally generated pump light of twice the optical frequency. Currently,
there is immense effort in miniaturizing squeezed-light sources for
chip-integration. Designs that require just a single input wavelength are
favored since they offer an easier realization. Here we report on the first
direct observation of cw squeezed vacuum states generated by self-phase
modulation. The wavelengths of input light and of balanced homodyne detection
are identical, and 1550 nm in our case. At sideband frequencies around 1.075
GHz, a nonclassical noise reduction of (2.4 +/- 0.1) dB is observed. The setup
uses a second-order nonlinear crystal, but no externally generated light of
twice the frequency. Our experiment is not miniaturized, but might open a route
towards simplified chip-integrated realizations.
