A team of physicists led by Dr. Yuan Lu from the Université de Lorraine’s Institut Jean Lamour has used electrical pulses to manipulate magnetic information into a polarized light signal — a discovery that could revolutionize long-distance optical telecommunications, including between Earth and Mars. The breakthrough involves the field of spintronics, which aims to manipulate the spin of electrons in order to store and process information.
In spintronics, which has been used successfully in magnetic computer hard drives, information is represented by electron spin and, by its proxy, the direction of magnetization.
Ferromagnets, such as iron or cobalt, have an unequal number of electrons whose spins are oriented either along or against the magnetization axis.
Electrons with spin along the magnetization travel smoothly across a ferromagnet, while those with opposite spin orientation are bounced around. This represents binary information, 0 and 1.
The resulting change of the resistance is the key principle for spintronic devices, whose magnetic state, which can be considered as stored information, is maintained indefinitely.
Just as a fridge magnet does not need power to remain stuck to the door, spintronic devices would require much less power than conventional electronics.
However, akin to taking a fish out of water, spin information is quickly lost and cannot travel far when electrons are taken out of the ferromagnet.
This major limitation can be overcome by utilizing light through its circular polarization, also known as helicity, as another spin carrier.
Just as humans centuries ago used carrier pigeons to transport written communication farther and faster than could be done on foot, the trick would be to transfer electron spin to photos, the quantum of light.
The presence of spin-orbit coupling, which is also responsible for the spin information loss outside of the ferromagnet, makes such transfer possible.
The crucial missing link is then to…
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