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Quantum Metrology of Noisy Spreading Channels
Wojciech Górecki1, Alberto Riccardi2, Lorenzo Maccone2
1Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland.
Physical Review Letters
|December 23, 2022
Summary
We found the best way to measure parameters in noisy spreading channels. Using squeezed light states offers a quantum advantage, improving precision beyond classical limits for displacement estimation.
Area of Science:
- Quantum information science
- Quantum metrology
- Optical physics
Background:
- Noisy channels can degrade quantum information.
- Parameter estimation is crucial in quantum technologies.
- Spreading channels simplify to identity channels under specific conditions.
Purpose of the Study:
- To determine the optimal measurement strategy for spreading channels.
- To investigate the impact of phase-randomizing noise on parameter estimation.
- To explore quantum advantages in precision measurement.
Main Methods:
- Analysis of noisy quantum channels.
- Theoretical modeling of parameter estimation strategies.
- Comparison of quantum probe states (squeezed vacuum, Fock states) with classical states.
- Calculation of quantum Fisher information.
Main Results:
- Optimal measurement strategy identified for spreading channels.
- Phase-randomizing noise does not hinder optimal measurement effectiveness for displacement estimation.
- Squeezed vacuum probe states are optimal for small displacements at equivalent energy.
- Homodyne detection becomes ineffective for small displacements, unlike optimal strategies.
Conclusions:
- Squeezed states provide a significant quantum advantage in precision for parameter estimation.
- Optimal measurement strategies can overcome limitations imposed by certain types of noise.
- Quantum metrology offers superior precision compared to classical methods using similar energy resources.
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