Experimental Demonstration of a Cheap and Accurate Phase Estimation

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Metrology

Background:

• Accurate phase estimation is crucial for quantum computation and metrology.
• Standard phase estimation protocols often require ideal experimental conditions and auxiliary qubits.
• Trapped ion qubits offer a promising platform for implementing quantum information tasks.

Purpose of the Study:

• To experimentally implement and validate robust phase estimation (RPE) for a single-qubit rotation on a trapped Ytterbium-ion qubit.
• To demonstrate that RPE can achieve high precision with a limited number of experimental samples.
• To compare the performance of RPE against established quantum characterization techniques.

Main Methods:

• Experimental implementation of robust phase estimation (RPE) on a single-qubit gate of a trapped Ytterbium-ion qubit.
• Utilizing a minimal number of experimental samples (176) for phase estimation.
• Cross-validation of RPE results using gate set tomography (GST).

Main Results:

• Achieved phase estimation uncertainty below 4×10⁻⁴ radians.
• Demonstrated Heisenberg scaling of estimation uncertainty with the number of samples.
• RPE successfully estimated the phase without assuming perfect state preparation and measurement, and without requiring ancilla qubits.

Conclusions:

• Robust phase estimation (RPE) provides a resource-efficient and highly accurate method for learning quantum gate parameters.
• The experimental demonstration on a trapped Ytterbium-ion qubit validates RPE's practical applicability.
• RPE offers a viable alternative to more resource-intensive protocols like gate set tomography for quantum characterization.