Quantum States with a Positive Partial Transpose are Useful for Metrology
Géza Tóth1,2,3, Tamás Vértesi4
1Department of Theoretical Physics, University of the Basque Country UPV/EHU, P.O. Box 644, E-48080 Bilbao, Spain.
Physical Review Letters
|January 30, 2018
Summary
Multipartite quantum states with a positive partial transpose can enhance precision in linear interferometers, outperforming classical states. A novel iterative method was developed to discover these states, showing robustness against noise.
Area of Science:
- Quantum Information Science
- Quantum Metrology
- Quantum Many-Body Physics
Background:
- Separable quantum states set a baseline for precision in quantum metrology.
- Multipartite entanglement is a key resource for quantum information processing.
- The positive partial transpose (PPT) condition is often associated with separability, but not always.
Purpose of the Study:
- To investigate whether quantum states with a positive partial transpose (PPT) can surpass separable states in metrological applications.
- To develop an efficient method for constructing such advantageous quantum states.
- To explore the relationship between metrological usefulness and Bell inequality violation.
Main Methods:
- Development of an iterative algorithm to identify multipartite quantum states.
- Analysis of quantum states with positive partial transpose (PPT) for metrological applications.
- Investigation of entanglement robustness against noise in bipartite systems.
- Examination of Bell inequality violation as a measure of quantum correlations.
Main Results:
- Demonstration that PPT quantum states can outperform separable states in linear interferometers.
- Introduction of an iterative method for discovering these high-performance states.
- Observation of noise-robust entanglement in specific bipartite examples.
- Finding that metrological advantage is not strictly tied to Bell inequality violation; PPT states without violation can still be superior.
Conclusions:
- Quantum states with positive partial transpose (PPT) offer a viable route to enhanced metrology, even without violating Bell inequalities.
- The developed iterative method provides a powerful tool for finding states that optimize precision.
- Entanglement properties, including noise resilience, are crucial for advanced quantum sensing applications.
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