A sensitive electrometer based on a Rydberg atom in a Schrödinger-cat state

Area of Science:

• Quantum Metrology
• Atomic Physics
• Electromagnetism

Background:

• Heisenberg's uncertainty principle fundamentally limits measurement precision.
• Exceeding the standard quantum limit typically requires non-classical states, which are difficult to prepare in large systems.
• Previous methods were restricted to small angular momentum systems for non-classical state metrology.

Purpose of the Study:

• To demonstrate electric field measurement beyond the standard quantum limit using a large angular momentum system.
• To explore the metrological potential of Schrödinger-cat states in Rydberg atoms for enhanced precision.

Main Methods:

• Utilized a single atom in a high-energy Rydberg state as an electrometer with large angular momentum (J ≈ 25).
• Engineered a non-classical evolution of the Rydberg atom through Schrödinger-cat states.
• Performed electric field measurements with a 100-nanosecond interaction time.

Main Results:

• Achieved a single-shot sensitivity of 1.2 mV/cm.
• Demonstrated a sensitivity of 30 µV/cm/√Hz at a 3 kHz repetition rate.
• Approached the fundamental Heisenberg limit for measurement precision.

Conclusions:

• This work establishes a new realm for highly sensitive, non-invasive electrometric techniques.
• The developed method using Rydberg atoms and non-classical states offers a pathway to overcome standard quantum limits.
• Potential applications include detecting individual electrons in mesoscopic devices with high spatial and temporal resolution.