Optimal metrology with programmable quantum sensors

Area of Science:

• Quantum information processing
• Metrology
• Quantum sensing technology

Background:

• Quantum sensors offer advanced precision but achieving fundamental quantum limits remains challenging.
• Entanglement-enhanced quantum sensors represent the next frontier in precision measurement.

Purpose of the Study:

• To experimentally implement a programmable quantum sensor that operates near the fundamental precision limits.
• To merge quantum information processing with metrology for enhanced sensing capabilities.

Main Methods:

• Utilized low-depth, parametrized quantum circuits on a trapped-ion experiment.
• Implemented optimal input states and measurement operators for a sensing task.
• Employed on-device quantum-classical feedback for self-calibration.

Main Results:

• Approached the fundamental sensing limit by a factor of 1.45 ± 0.01 using 26 ions.
• Outperformed conventional spin-squeezing by a factor of 1.87 ± 0.03.
• Reduced the number of averages needed for a target Allan deviation by a factor of 1.59 ± 0.06.

Conclusions:

• Demonstrated a programmable quantum sensor operating close to quantum mechanical limits.
• The developed sensor surpasses traditional methods and entanglement-assisted spin-squeezing.
• Self-calibration capability allows for operation without prior knowledge of the sensor or its noise environment.