A team of scientists from NUST MISIS and MIPT have developed and tested a
new platform for realization of the ultra-strong photon-to-magnon coupling.
The proposed system is on-chip and is based on thin-film hetero-structures
with superconducting, ferromagnetic and insulating layers. This discovery
solves a problem that has been on the agenda of research teams from
different countries for the last 10 years, and opens new opportunities in
implementing quantum technologies. The study was published in the highly
ranked journal Science Advances.
The last decade has seen significant progress in the development of
artificial quantum systems. Scientists are exploring different platforms,
each with its own advantages and disadvantages. The next critical step for
advancing quantum industry requires an efficient method of information
exchange between platform hybrid systems that could benefit from distinct
platforms. For example, hybrid systems based on collective spin excitations,
or magnons, are being developed. In such systems, magnons must interact with
photons, standing electromagnetic waves trapped in a resonator. The main
limiting factor for developing such systems is the fundamentally weak
interaction between photons and magnons. They are of different sizes, and
follow different dispersion laws. This size difference of a hundred times or
more considerably complicates the interaction.
Scientists from MIPT, together with their colleagues, managed to create a
system with what is called the ultra-strong photon-to-magnon coupling.
Vasily Stolyarov, deputy head of the MIPT Laboratory of Topological Quantum
Phenomena in Superconducting Systems, commented, "We created two subsystems.
In one, being a sandwich from superconductor/insulator/superconductor thin
films, photons are slowed down, their phase velocity is reduced. In another
one, which is also a sandwich from superconductor/ ferromagnetic/
superconductor thin films, superconducting proximity at both interfaces
enhances the collective spin eigen-frequencies. The ultra strong
photon-to-magnon coupling is achieved thanks to the suppressed photon phase
velocity in the electromagnetic subsystem."
Igor Golovchanskiy, leading researcher, senior researcher at the MIPT
Laboratory of Topological Quantum Phenomena in Superconducting Systems, head
of the NUST MISIS Laboratory of Cryogenic Electronic Systems, explained,
"Photons interact very weakly with magnons. We managed to create a system in
which these two types of excitations interact very strongly. With the help
of superconductors, we have significantly reduced the electromagnetic
resonator. This resulted in a hundred times reduction of the phase velocity
of photons, and their interaction with magnons increased by several times."
This discovery will accelerate the implementation of hybrid quantum systems,
as well as open up new possibilities in superconducting spintronics and
magnonics.
Reference:
Igor A. Golovchanskiy et al, Ultrastrong photon-to-magnon coupling in
multilayered heterostructures involving superconducting coherence via
ferromagnetic layers, Science Advances (2021). DOI:
10.1126/sciadv.abe8638