https://doi.org/10.1140/epjqt/s40507-022-00154-x
Research
Transmission estimation at the quantum Cramér-Rao bound with macroscopic quantum light
1
Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, 73019, Norman, Oklahoma, USA
2
Center for Quantum Research and Technology, The University of Oklahoma, 73019, Norman, Oklahoma, USA
3
Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile
4
ANID – Millennium Science Initiative Program – Millennium Institute for Research in Optics (MIRO), Santiago, Chile
5
OAM Photonics LLC, 92126, San Diego, California, USA
6
Quantum Information Science Section, Oak Ridge National Laboratory, 37381, Oak Ridge, Tennessee, USA
7
Quantum Science Center, Oak Ridge National Laboratory, 37381, Oak Ridge, Tennessee, USA
d marino@ou.edu, marinoa@ornl.gov
Received:
10
September
2022
Accepted:
18
November
2022
Published online:
22
December
2022
The field of quantum metrology seeks to apply quantum techniques and/or resources to classical sensing approaches with the goal of enhancing the precision in the estimation of a parameter beyond what can be achieved with classical resources. Theoretically, the fundamental minimum uncertainty in the estimation of a parameter for a given probing state is bounded by the quantum Cramér-Rao bound. From a practical perspective, it is necessary to find physical measurements that can saturate this fundamental limit and to show experimentally that it is possible to perform measurements with the required precision to do so. Here we perform experiments that saturate the quantum Cramér-Rao bound for transmission estimation over a wide range of transmissions when probing the system under study with a continuous wave bright two-mode squeezed state. To properly take into account the imperfections in the generation of the quantum state, we extend our previous theoretical results to incorporate the measured properties of the generated quantum state. For our largest transmission level of 84%, we show a 62% reduction over the optimal classical protocol in the variance in transmission estimation when probing with a bright two-mode squeezed state with −8 dB of intensity-difference squeezing. Given that transmission estimation is an integral part of many sensing protocols, such as plasmonic sensing, spectroscopy, calibration of the quantum efficiency of detectors, etc., the results presented promise to have a significant impact on a number of applications in various fields of research.
Key words: Quantum metrology / Quantum sensing / Quantum Cramér-Rao bound / Quantum Fisher information / Quantum optics / Transmission estimation
© UT-Battelle, LLC 2022
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