Detection Loss Tolerant Supersensitive Phase Measurement with an SU(1,1) Interferometer.

Area of Science:

• Quantum optics
• Interferometry
• Nonlinear optics

Background:

• Traditional interferometers are limited by the shot noise limit.
• Achieving sub-shot-noise sensitivity is crucial for advanced measurements.
• Parametric amplifiers offer a route to enhanced sensitivity.

Purpose of the Study:

• To demonstrate phase sensitivity surpassing the shot noise limit in an unseeded SU(1,1) interferometer.
• To investigate the tolerance of the interferometer to detection losses.
• To explore the potential for improved quantum imaging and measurements in lossy environments.

Main Methods:

• Utilizing an unseeded SU(1,1) interferometer with two cascaded degenerate parametric amplifiers.
• Employing direct detection at the interferometer's output.
• Implementing a strongly unbalanced configuration with differential parametric gain.

Main Results:

• Achieved phase sensitivity exceeding the shot noise limit by 2.3 dB.
• Demonstrated preservation of phase supersensitivity even with up to 80% detection losses.
• Showcased the impact of increasing the second amplifier's gain on loss tolerance.

Conclusions:

• The developed SU(1,1) interferometer offers significant improvements over state-of-the-art interferometry.
• Sub-shot-noise phase sensitivity can be maintained in spectral ranges with inefficient detectors.
• The findings pave the way for enhanced quantum imaging and metrology applications.