- Quantum tomography is a relatively new discipline.
- It started with Fano theoretical work.
- The Raymer group is the trailblazer that started such experiments.
Russian physicists at the MGU center for quantum technologies, together with a group of scientists from Skoltech under the direction of Jacob Biamonte used a deep neural network to analyze experimental data for quantum tomography of the spatial states of photons. The method proved to be much more effective than the traditional methods used in such cases. The results of the study have been published in the journal of the Quantum Information.
MGU is a coeducational and a public research university located in Moscow, Russia. It was founded on 23 January [O.S. 12 January] 1755 by Mikhail Lomonosov. During the Soviet period, MSU was renamed after Lomonosov in 1940 and was then known as Lomonosov University.
The Skolkovo Institute of Science and Technology is a private institute located in Moscow, Russia. Skoltech was established in 2011 as part of a multi-year partnership with the Massachusetts Institute of Technology.
With evolving quantum technologies, the complexity of the quantum devices have been rapidly expanding. The project was able to develop characterization and debugging methods in corresponding theoretical models. Hence, the quantum tomography methodology.
Quantum tomography or quantum state tomography is the process of reconstructing the quantum state for a source of quantum systems by measurements on the systems coming from the source.
Quantum tomography is a relatively new discipline. It started with Fano theoretical work.
Ugo Fano was born to Rosa Cassin and Gino Fano (1871-1952), professor of mathematics at Turin, Italy, specializing in differential geometry. Having studied mathematics first at the University of Turin, the younger Fano turned to physics under the influence of his cousin, Giulio Racah (1909-1965), a physicist known for the powerful theory of angular momentum. Then Fano was fortunate to receive postdoctoral training from two giants in modern physics: Enrico Fermi at Rome in 1934-1936 and Werner Heisenberg at Leipzig in 1936-1937.
The Raymer group is the trailblazer that started such experiments. Michael G. Raymer’s research focuses on the quantum mechanics of light and its interaction with atoms and molecules, with applications in nonlinear optics, quantum communications technology, and quantum information. In the 1993 his group reported the first instance of experimental quantum-state tomography of light.
Scientists of Moscow State University and Skoltech examined the spatial state of the photons. In experiments the measurement was made using special holograms that convert the phase of the light beam, which is then focused into a single-mode fiber. These holograms do not work perfectly, and the larger the dimension of the quantum state, the more “small features” in the beam structure, and accordingly, the more difficult it is to make a good measurement. The traditional method of correcting” noisy data obtained experimentally is to measure the resulting “imperfections” and analytically construct a system of corrections that takes them into account.
Using a deep neural network instead of the traditional method, the researchers concluded that it makes it more effective than the traditional method to get rid of experimental noise during the measurement process and significantly improves the quality of state recovery. The architecture and training methods of the neural network used in the experiment were developed by a group of scientists from Skoltech.