Multi-Parameter Quantum Measurement

There are 3 modules in the experiment: state preparation, evolution, and measurement. Credit: HOU Zhibo et al.

Real-life applications like magnetometry or quantum gyroscope usually involve exact measurement on numerous criteria. How to achieve the supreme precision limitations at the same time is a long desired grail in the field.

It is extensively thought that the supreme precision limitations for all specifications can not be achieved concurrently, considering that generators of various parameters are typically non-commuting, which causes the compromises among the accuracies.

Yet such compromises are gotten away from by the group of Prof. LI Chuanfeng and Prof. XIANG Guoyong from Key Lab of Quantum Details at University of Science and Innovation of China of the Chinese Academy of Sciences and their collaborator Prof. YUAN Haidong from Chinese University of Hongkong.

They counteracted the compromises and attained the precision limit for the evaluation of all 3 parameters in SU( 2) operators all at once with 13.27 dB enhancement over the shot-noise limitation, which has actually been released in journal Science Advances

XIANG and researchers extended the control-enhanced sequential measurement scheme from single-parameter evaluation to multi-parameter estimation.

They related the simultaneous multi-parameter quantum estimation directly to the Heisenberg unpredictability relations and revealed that to achieve the precision limitation for multiple specifications simultaneously requires the simultaneous saturation of the minimum uncertainty in numerous Heisenberg unpredictability relations.

As the first speculative presentation of multi-parameter quantum evaluation with no trade-off, the work reveals the deep connection between quantum metrology and the Heisenberg unpredictability concept and marks an important action towards accomplishing the ultimate precision of multi-parameter quantum evaluation.

XIANG’s group have been devoted to counteracting the trade-offs in multi-parameter estimation. They first developed new speculative measurement techniques of cumulative measurements, which effectively decreased the trade-offs in quantum state tomography and quantum orienteering. They optimized the entangled probe states in quantum magnetometry and got the ultimate precision limitation for three magnetic parts with minimum trade-offs. Lessened, the compromises still exist in these past works.

Recommendation: “No– compromise multiparameter quantum estimate by means of at the same time saturating multiple Heisenberg uncertainty relations” by Zhibo Hou, Jun-Feng Tang, Hongzhen Chen, Haidong Yuan, Gou-Yong Xiang, Chuan-Feng Li and Guang-Can Guo, 1 January 2021, Science Advances.
DOI: 10.1126/ sciadv.abd2986

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