Approaching the Multiparameter Quantum Cramér-Rao Bound via Classical Correlation and Entangling Measurements

Area of Science:

• Quantum physics
• Metrology
• Quantum information science

Background:

• Multiparameter quantum metrology is crucial for various applications.
• Achieving the quantum Cramér-Rao bound (QCRB) for all parameters simultaneously is a major challenge.

Purpose of the Study:

• To propose and experimentally validate a novel quantum metrology scheme.
• To demonstrate the attainment of the multiparameter QCRB.
• To achieve Heisenberg scaling precision in multiparameter estimation.

Main Methods:

• Introduced the Local Operation with Entangling Measurements (LOEM) strategy.
• Utilized classically correlated orthogonal pure states.
• Employed entangling measurements and iterative interactions.
• Experimentally validated the scheme using a quantum photonic system.

Main Results:

• The LOEM strategy successfully attains the multiparameter QCRB.
• Experimental validation confirmed the scheme's effectiveness in a photonic system.
• Iterative interactions demonstrated Heisenberg scaling precision.

Conclusions:

• The LOEM strategy enables simultaneous achievement of the ultimate precision for multiparameter estimation.
• This work advances practical quantum metrology applications.
• The demonstrated saturation of the multiparameter QCRB is a significant breakthrough.