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Review
. 2025 Jul 1;27(7):712.
doi: 10.3390/e27070712.

Experimental Advances in Phase Estimation with Photonic Quantum States

Laura T Knoll  1   2 , Agustina G Magnoni  1   2 , Miguel A Larotonda  1   2
Affiliations
Review

Experimental Advances in Phase Estimation with Photonic Quantum States

Laura T Knoll et al. Entropy (Basel). .

Abstract

Photonic quantum metrology has emerged as a leading platform for quantum-enhanced precision measurements. By taking advantage of quantum resources such as entanglement, quantum metrology enables parameter estimation with sensitivities surpassing classical limits. In this review, we describe the basic tools and recent experimental progress in the determination of an optical phase with a precision that may exceed the shot-noise limit, enabled by the use of nonclassical states of light. We review the state of the art and discuss the challenges and trends in the field.

Keywords: photonic quantum phase estimation; quantum metrology; quantum parameter estimation.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Quantum estimation process. An initial probe state is prepared and sent to interact with a quantum operation that encodes the parameter to be estimated. Measurements are then performed on the output state, and an estimator is inferred from the measured probability distributions.
Figure 2
Figure 2
A schematic representation of a Mach–Zehnder interferometer for phase estimation in a classic framework. A probe state is sent to the apparatus through inputs 1 and 2, where a two-mode superposition state is created at the first beamsplitter. This state interacts with a phase encoding mechanism. The phase can be estimated from measurements of a specific observable at outputs 3 and 4 after the coherent recombination of the two modes at the output beamsplitter.
Figure 3
Figure 3
Scheme for HOM interference. Two identical single photons enter ports 1 and 2 of a beamsplitter and exit bunched together through one or the other output port, illustrated by the double green and red arrows.
See this image and copyright information in PMC

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