5 research outputs found
Wireless power transfer in magnetic resonance imaging at a higher-order mode of a birdcage coil
Magnetic resonance imaging (MRI) is a crucial tool for medical visualization.
In many cases, performing a scanning procedure requires the use of additional
equipment, which can be powered by wires as well as via wireless power transfer
(WPT) or wireless energy harvesting. In this Letter, we propose a novel scheme
for WPT that uses a higher-order mode of the MRI scanner's birdcage coil for
energy transmission. In contrast to the existing WPT solutions, our approach
does not require additional transmitting coils. Compared to the energy
harvesting, the proposed method allows supplying significantly more power. We
perform numerical simulations demonstrating that one can use the fundamental
mode of the birdcage coil to perform a scanning procedure while transmitting
the energy to the receiver at a higher-order mode without any interference with
the scanning signal or violation of safety constraints, as guaranteed by the
mode structure of the birdcage. Also, we evaluate the specific absorption rate
along with the energy transfer efficiency and verify our numerical model by a
direct comparison with an experimental setup featuring a birdcage coil of a
1.5T MRI scanner.Comment: 6 pages, 5 figures + Supplementary Material 10 pages, 7 figure
Photon-Mediated Localization in Two-Level Qubit Arrays
We predict the existence of a novel interaction-induced spatial localization in a periodic array of qubits coupled to a waveguide. This localization can be described as a quantum analogue of a self-induced optical lattice between two indistinguishable photons, where one photon creates a standing wave that traps the
other photon. The localization is caused by the interplay between on-site repulsion due to the photon blockade and the waveguide-mediated long-range coupling between the qubits.C. L. was supported by
the National Natural Science Foundation of China (NNSFC)
(Grants No. 11874434 and No. 11574405). Y. K. was
partially supported by the Office of China Postdoctoral
Council under Grant No. 20180052 and the National Natural
Science Foundation of China (NNSFC) under Grant
No. 11904419. A. V. P. also acknowledges a partial support
from the Russian President Grant No. MK-599.2019.2.
A. V. P., A. N. P., and N. A. O. have been partially supported
by the Foundation for the Advancement of Theoretical
Physics and Mathematics “BASIS.” N. A. O. was supported
by the Russian Foundation for Basic Research (Grants
No. 18-29-20037 and No. 18-32-01052)
Swarmodroid 1.0: A Modular Bristle-Bot Platform for Robotic Active Matter Studies
Large swarms of extremely simple robots (i.e., capable just of basic motion
activities, like propelling forward or self-rotating) are widely applied to
study collective task performance based on self-organization or local
algorithms instead of sophisticated programming and global swarm coordination.
Moreover, they represent a versatile yet affordable platform for experimental
studies in physics, particularly in active matter - non-equilibrium assemblies
of particles converting their energy to a directed motion. However, a large set
of robotics platforms is being used in different studies, while the universal
design is still lacking. Despite such platforms possess advantages in certain
application scenarios, their large number sufficiently limits further
development of results in the field, as advancing some study requires to buy or
manually produce the corresponding robots. To address this issue, we develop an
open-source Swarmodroid 1.0 platform based on bristle-bots with reconfigurable
3D-printed bodies, external control of motion velocity, and basic capabilities
of velocity profile programming. In addition, we introduce AMPy software
package in Python featuring OpenCV-based extraction of robotic swarm kinematics
accompanied by the evaluation of key physical quantities describing the
collective dynamics. We perform a detailed analysis of individual Swarmodroids'
motion characteristics and address their use cases with two examples: a cargo
transport performed by self-rotating robots and a velocity-dependent jam
formation in a bottleneck by self-propelling robots. Finally, we provide a
comparison of existing centimeter-scale robotic platforms, a review of key
quantities describing collective dynamics of many-particle systems, and a
comprehensive outlook considering potential applications as well as further
directions for fundamental studies and Swarmodroid 1.0 platform development.Comment: 18 pages, 7 figures, 1 table + Supplementary Information. Comments
are welcom