Laser Cooling and Qubit Measurements on a Forbidden Transition in Neutral Cs Atoms

Area of Science:

• Atomic Physics
• Quantum Metrology
• Laser Cooling and Trapping

Background:

• Precise manipulation and measurement of individual atoms are crucial for quantum technologies.
• Existing methods often suffer from background noise or limited resolution.
• Cesium (Cs) atoms are widely used in atomic clocks and quantum information processing.

Purpose of the Study:

• To demonstrate background-free, hyperfine-level-selective measurements of individual Cs atoms.
• To achieve high fidelity and atom retention for reliable quantum state detection.
• To explore methods for repeated, low-loss measurements of atomic states.

Main Methods:

• Simultaneous cooling of Cs atoms to 5.3 μK.
• Imaging on the 6s_{1/2}→5d_{5/2} electric-quadrupole transition.
• Utilizing a 3D cooling configuration for state measurements.
• Theoretical analysis of an auxiliary field-based excited state quenching method.

Main Results:

• Achieved hyperfine-resolved detection with a fidelity of 0.9993(4).
• Demonstrated atom retention of 0.9954(5), limited by vacuum lifetime.
• Repeated low-loss measurements were enabled by the 3D cooling setup.
• Projected fidelity of ~0.9995 in ~60 μs for the extended approach.

Conclusions:

• The demonstrated technique provides background-free, high-fidelity measurements of individual Cs atoms.
• The method is suitable for repeated, low-loss atomic state detection.
• The proposed extension offers potential for even faster and more precise measurements.