Physicists create quantum-inspired optical sensor

Apparatus for measuring the position of an object using optical coherence alone. Credit: Nikita Kirsanov/MIPT

Researchers from the Moscow Institute of Physics and Technology and Argonne National Laboratory, U.S. have implemented an advanced quantum algorithm for measuring physical quantities using simple optical tools. Their study takes us a step closer to affordable linear optics-based sensors with high performance characteristics.

Until recently, no measurement tool could ensure precision above the so-called shot noise limit, which has to do with the statistical features inherent in classical observations. Quantum technology has provided a way around this, boosting precision to the fundamental Heisenberg limit, stemming from the basic principles of quantum mechanics.

Quantum metrology is a cutting-edge area of physics concerned with the technological and algorithmic tools for making highly precise quantum measurements. In their study, the researchers fused quantum metrology with linear optics. They devised and constructed an optical scheme that runs the Fourier transform-based phase estimation procedure which lies at the core of many quantum algorithms, including high-precision measurement protocols.

A specific arrangement of a very large number of linear optical elements—beam splitters, phase shifters, and mirrors—makes it possible to gain information about the geometric angles, positions, velocities as well as other parameters of physical objects. The measurement involves encoding the quantity of interest in the optical phases, which are then determined directly.

The experiment showed that despite the large number of optical elements in the scheme, it is nevertheless tunable and controllable. The study has demonstrated that linear optics offers an affordable and effective platform for implementing moderate-scale quantum measurements and computations. (

The study has been published in Scientific Reports.

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