An advanced quantum algorithm has been executed by scientists from the Moscow Institute of Physics and Technology, together with a collaborator from Argonne National Laboratory, United States, to measure physical quantities with simple optical tools.
The study, which has been reported in Scientific Reports, is one step closer to low-cost linear optics-based sensors that exhibit higher performance. There is a demand for such tools in various research fields, ranging from biology to astronomy.
In any field of science and technology, it is vital to maximize the sensitivity of measurement tools. Engineers seek to measure the velocities and positions of objects, astronomers have to detect remote cosmic phenomena, and biologists must discern extremely tiny organic structures, for instance.
To date, none of the measurement tools have been able to ensure precision over what is called the shot-noise limit, which is associated with the statistical features intrinsic to classical observations. Quantum technology has offered a means to overcome this by optimizing precision to the fundamental Heisenberg limit, which arises from the fundamental principles of quantum mechanics.
The LIGO experiment, which was the first to detect gravitational waves in 2016, demonstrates that it is feasible to realize Heisenberg-limited sensitivity by integrating quantum techniques with complex optical interference schemes.
Quantum metrology is a novel area of physics that is related to the algorithmic and technological tools for making highly accurate quantum measurements. In the latest study, the researchers from MIPT and ANL combined quantum metrology with linear optics.
We devised and constructed an optical scheme that runs the Fourier transform-based phase estimation procedure. This procedure lies at the core of many quantum algorithms, including high-precision measurement protocols.
Nikita Kirsanov, Study Co-Author, MIPT
When a huge number of linear optical elements—including mirrors, phase shifters, and beam splitters—are arranged in a specific way, it is feasible to acquire information about the positions, geometric angles, velocities, and other parameters of physical objects. As part of the measurement, the quantity of interest is encoded in the optical phases, which are directly determined later.
This research is a follow-up to our work on universal quantum measurement algorithms. In an earlier collaboration with a research group from Aalto University in Finland, we experimentally implemented a similar measurement algorithm on transmon qubits.
Gordey Lesovik, Principal Investigator and Head, Laboratory of the Physics of Quantum Information Technology, MIPT
Through the experiment, it was demonstrated that the scheme is controllable and tunable despite the huge number of optical elements in it. The theoretical estimates offered by the paper suggest that optics tools can be used for executing even operations that are much more complex.
The study has demonstrated that linear optics offers an affordable and effective platform for implementing moderate-scale quantum measurements and computations.
Valerii Vinokur, Distinguished Fellow, Argonne National Laboratory
Zemlyanov, V. V., et al. (2020) Phase estimation algorithm for the multibeam optical metrology. Scientific Reports. doi.org/10.1038/s41598-020-65466-3.