A prototype differential atom interferometer for fundamental physics.

Area of Science:

• Fundamental Physics
• Quantum Sensing
• Astrophysics

Background:

• Gravitational waves and ultralight dark matter are key research areas in fundamental physics.
• Very-long-baseline atom interferometers are proposed for detecting signals at frequencies where other interferometers are less sensitive.
• Laser phase noise is a critical noise source that challenges the performance of these atom interferometers.

Purpose of the Study:

• To experimentally validate noise rejection techniques for very-long-baseline atom interferometers.
• To demonstrate a prototype differential atom interferometer capable of operating at the quantum limit.
• To advance the development of next-generation quantum sensors for gravitational-wave detection and dark matter searches.

Main Methods:

• Demonstrated a prototype differential atom interferometer using the single-photon clock transition of fermionic strontium-87.
• Configured the instrument as a gradiometer suitable for kilometer-scale and space-baseline operations.
• Artificially injected significant laser phase noise to emulate conditions in very-long-baseline atom interferometers.

Main Results:

• The interferometer operated at the standard quantum limit with no excess noise beyond atom shot noise.
• Quantum-limited sensitivity was maintained despite several radians of injected laser phase noise.
• Coherent oscillatory signals were recovered across a broad frequency range under phase-randomized conditions.

Conclusions:

• Experimental validation of the noise-immune measurement principle for very-long-baseline atom interferometers was achieved.
• The prototype demonstrates a significant step towards next-generation quantum sensors.
• This technology holds promise for gravitational-wave detection and ultralight dark matter searches.