Quantum-amplified global-phase spectroscopy on an optical clock transition.

Area of Science:

• Quantum metrology
• Atomic clocks
• Precision measurement

Background:

• Optical lattice clocks are state-of-the-art in precision metrology.
• They operate near the standard quantum limit imposed by quantum noise.
• Quantum entanglement offers a path beyond this limit but faces scalability and resolution challenges.

Purpose of the Study:

• To develop a novel spectroscopy technique for optical clocks.
• To surpass the standard quantum limit in metrology and improve laser noise sensitivity.
• To address scalability and resolution limitations in quantum-enhanced metrology.

Main Methods:

• Adaptation of the holonomic quantum gate concept.
• Development of a Rabi-type 'global-phase spectroscopy' utilizing the Aharonov-Anandan phase.
• Implementation of rotary echo for protection against coupling inhomogeneities and differential measurement for laser noise cancellation.

Main Results:

• Demonstration of quantum-amplified time-reversal spectroscopy on an optical clock transition.
• Achieved 2.4(7) dB metrological gain beyond the standard quantum limit.
• Achieved 4.0(8) dB improvement in laser noise sensitivity.

Conclusions:

• The developed technique overcomes limitations of measurement resolution and scales easily.
• It shows high resilience to experimental imperfections.
• The method is broadly applicable to next-generation atomic clocks and quantum sensors.