Researchers from the University of Warsaw’s Faculty of Physics, in collaboration with experts from the QOT Centre for Quantum Optical Technologies, have made a major breakthrough in optical technology. They have developed a groundbreaking method to perform the fractional Fourier Transform of optical pulses using quantum memory, with potential applications in the fields of telecommunications and spectroscopy.
The fractional Fourier Transform is a generalization of the Fourier Transform, which allows for a partial transition from describing a wave in time to describing it in frequency. In simpler terms, it can be seen as a rotation of a signal’s distribution in the time-frequency domain. This transformation has proven to be exceptionally useful in creating spectral-temporal filters to eliminate noise and improve the precision of distinguishing pulses of different frequencies. This has significant implications in the fields of spectroscopy and telecommunications, which require high precision and speed in the transmission and processing of information.
To achieve this breakthrough, the researchers used a quantum memory equipped with quantum light processing capabilities based on a cloud of rubidium atoms placed in a magneto-optical trap. The atoms were cooled to a temperature tens of millions of degrees above absolute zero and were placed in a changing magnetic field. This setup allowed different frequencies of the pulse to be stored in different parts of the cloud. The pulse was subjected to a time lens during writing and reading, and a frequency lens acted on it during storage.
The device developed at the University of Warsaw is capable of implementing time and frequency lenses over a wide range of parameters in a programmable way. Although the implementation was done using a double optical pulse, also known as a “Schrödinger’s cat” state, which is fragile and prone to decoherence, the team was able to successfully operate on these dual-pulse states.
The results of this groundbreaking research were published in the prestigious journal Physical Review Letters. The team from the Quantum Optical Devices Laboratory and Quantum Memory Laboratory at the “Quantum Optical Technologies” center played a crucial role in this achievement. The research was carried out by two master’s students, Stanislaw Kurzyna and Marcin Jastrzebski, as well as two undergraduate students, Bartosz Niewelt and Jan Nowosielski. Dr. Mateusz Mazelanik and lab heads Dr. Michal Parniak and Prof. Wojciech Wasilewski also contributed to the project.
While further mapping and testing are required before direct application in telecommunications, this breakthrough method could prove to be crucial for optical receivers in state-of-the-art networks, including optical satellite links. The quantum light processor developed at the University of Warsaw enables the efficient discovery and testing of new protocols. This research opens up new possibilities for advancements in optical technology and its various applications.
Reference: “Experimental Implementation of the Optical Fractional Fourier Transform in the Time-Frequency Domain” by Bartosz Niewelt, Marcin Jastrzębski, Stanisław Kurzyna, Jan Nowosielski, Wojciech Wasilewski, Mateusz Mazelanik, and Michał Parniak, published in Physical Review Letters. DOI: 10.1103/PhysRevLett.130.240801. The research was conducted under the International Research Agendas program of the Foundation for Polish Science, co-financed by the European Union.