Continuous-wave squeezed states of light via 'up-down' self-phase modulation

Area of Science:

• Quantum optics
• Nonlinear optics

Background:

• Continuous-wave (cw) squeezed states of light are crucial for quantum technologies like sensing and secure communication.
• Traditional generation methods rely on parametric down-conversion, requiring a pump light source at twice the optical frequency.
• Miniaturization and chip-integration of squeezed light sources are key research goals.

Purpose of the Study:

• To demonstrate a new method for generating cw squeezed states of light.
• To explore simplified approaches for squeezed light generation, favoring single input wavelengths.
• To investigate the potential for chip-integrated quantum light sources.

Main Methods:

• Observation of cw squeezed states generated via self-phase modulation.
• Utilizing subsequent up and down conversions within a second-order nonlinear crystal.
• Employing balanced homodyne detection at the input light wavelength (1550 nm).

Main Results:

• First observation of cw squeezed states generated by self-phase modulation.
• Achieved nonclassical noise reduction of (2.4 ± 0.1) dB at sideband frequencies around 1.075 GHz.
• Demonstrated generation without externally produced pump light at twice the frequency.

Conclusions:

• Self-phase modulation offers a simplified route to generating cw squeezed states of light.
• The demonstrated method avoids the need for a frequency-doubled pump source.
• This approach may enable future simplified, chip-integrated squeezed light sources.