How “twistronics” could revolutionize medical imaging

By studying the properties of a graphene-based material, American researchers have revealed a rare type of superconductivity. In particular, medical imaging and quantum computing could benefit.

In materials science, researchers are often called upon to work with compounds with curious behavior. This is the case with graphene, a material whose innumerable hidden properties have yet to be discovered. For example, researchers have realized that when you superimpose several layers of graphene, and that you rotate them relative to each other following a “magic angle”Precise, a whole bunch of weird properties appear. It is the basis of a fairly recent field of research, called twistronics, who has already offered us a remarkable breakthrough we were telling you about last year.

Since its shy and very theoretical beginnings at the end of the 2000s, this budding discipline has gained ground with enormous advances 2017; multilayer graphene is now intriguing many cutting-edge laboratories which are studying the question of its concrete applications. Recently, a team from the prestigious Massachusetts Institute of Technology (MIT) has distinguished itself with the new fashionable toy among nanotechnicians. Their latest work indeed shows that a triple layer of graphene oriented at the magic angle (we will now speak of MATTG, for Magic Angle Twisted Trilayer Graphene) had superconducting properties… and not just any.

At very low temperatures, superconductors levitate in the magnetic field. © Mai-Linh Doan – WikiCommons

How is this superconductor different?

Superconductors are a family of materials, defined by their ability to conduct electricity without resistance under certain conditions. Inside, the electrons travel there in pairs, in the form of “Cooper pairs”. In the majority of superconductors, these two electrons have of quantum spins opposites. Because of this peculiarity, when the couple is exposed to a strong magnetic field, the electrons will “derail”; the surface then loses its superconducting properties.

This is where the peculiarity of this material lies; in the MATTG, the two electrons in the couple would apparently have identical spin. We then speak of “spin triplet”. Concretely, this means that this material is almost invulnerable to magnetic fields; it retains all of its properties up to 10 Tesla, which is three times more than traditional superconductors.

Medical imaging could be among the first to benefit from these technologies. © National Cancer Institute

Medical imaging rubs their hands

An extremely rare feature to our knowledge, which already suggests very concrete applications to physicists at MIT. For example, MRI machines used in medical imaging could take a real leap forward with such technology.

These devices operate using superconductors placed in a magnetic field; they resonate with tissue to produce an image. However, the precision of the machine depends directly on the intensity of the magnetic field. By replacing conventional superconductors with MATTGs, an MRI machine could produce much better quality images.

Credits: Google.

The next big step in quantum computing?

And obviously, how to talk about superconductors without mentioning quantum computing. This discovery could also revolutionize this discipline “very fragile” by nature, according to Pablo Jarillo-Herrero, Professor of Physics at MIT. Twenty years ago, scientists proposed several models to make quantum computers infinitely more reliable and robust. But all have a crippling flaw: they are based on a specific type of spin triplet, dont l’existence remains theoretical has never been demonstrated. Obviously, the fact of having identified a new spin triplet is therefore very exciting: could this be the missing piece of the puzzle, which could to propel quantum computing into high gear?

It’s still too early to tell, but MIT has already started work to verify this hypothesis. And in the event that it turns out to be false, it would still be a major discovery. “We don’t know if it’s this guy [de spin triplet]”, concède Jarillo-Herrero. “But even if this is not the case, it could facilitate the application of MATTGs to other materials, to reproduce this type of conductivity. This could be a major breakthrough ”, concludes the researcher. For such a recent technology, the twistronics never stop wowing us!

Research paper is available here.

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