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Using entanglement against noise in quantum metrology
Rafal Demkowicz-Dobrzański1, Lorenzo Maccone2
1Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa, Poland.
Physical Review Letters
|January 3, 2015
Summary
Noise impacts quantum metrology strategies. Entangled probes and external ancillas enhance precision, outperforming unentangled methods in noisy environments for better quantum measurements.
Area of Science:
- Quantum Information Science
- Quantum Metrology
- Quantum Sensing
Background:
- Unentangled sequential strategies match Heisenberg scaling in ideal quantum metrology.
- External ancillas are considered ineffective in noise-free quantum metrology.
Purpose of the Study:
- To investigate the influence of probe entanglement and external ancillas on quantum metrology precision under noisy conditions.
- To establish a hierarchy of quantum metrology strategies in the presence of noise.
Main Methods:
- Analysis of entanglement's role among probes and with external ancillas.
- Investigation of specific quantum noise models.
- Theoretical proof of precision enhancement through entanglement and ancillas.
Main Results:
- Entangled strategies demonstrate superior precision compared to unentangled ones in noisy quantum metrology.
- Passive external ancillas can significantly increase measurement precision when noise is present.
- A general hierarchy for quantum metrology strategies in noisy scenarios is conjectured.
Conclusions:
- Entanglement and external ancillas are crucial for robust quantum metrology in realistic, noisy environments.
- The findings challenge previous assumptions about the limitations of unentangled strategies and ancillas.
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