It’s a Kind of Magic! Researchers Make Versatile Quantum Devices Out of Graphene

Is this a feat of astonishing wizardry?

Certainly, we are not wielding any wand in Hogwarts, but for researchers at the Massachusetts Institute of Technology, it seems something really closer.

In their study, "Highly tunable junctions and non-local Josephson effect in magic-angle graphene tunnelling devices" published in Nature Nanotechnology, MIT researchers have magically turned material made of atomically thin layers of carbon into three useful electronic devices. These devices, which are all important to the quantum electronics realm, were made utilizing different materials that need multiple fabrication steps. This method solves several problems associated with more complex processes.

Opening the Floodgates for New-Gen Quantum Devices

Their work could open the floodgates for a new generation of quantum electronic devices for quantum computing applications. In addition, these devices can also be superconducting, which means it could conduct electricity without any resistance. They achieve this using an unconventional mechanism that, with additional research, would offer new insights into the physics of superconductivity.

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The researchers showed that the magic angle graphene is the most versatile among superconducting materials, which allowed them to craft multiple quantum electronic devices in a single system, said Pablo Jarillo-Herrero, the Cecil, and Ida Green Professor of Physics at MIT and leader in the study, in a Phys.Org article. Jarillo-Herrero is also part of MIT's Materials Research Laboratory.

"Magic" Material Made of Graphene

This "magic" material, as Jarillo-Herrero said, is made of graphene, which is composed of a single layer of carbon atoms that are arranged in hexagons. Discovered only 17 years ago, graphene has a wide range of astonishing properties. It is considered stronger than diamond and is flexible and transparent. Graphene likewise conducts heat and electricity.

Jarillo-Herrero and his team experimented in 2018 placing two layers of graphene on top of the other. The two layers were not exactly on top of the other but slightly turned at a "magic angle" of 1.1 degrees.

The structure, as a result, allowed the material to either be a superconductor or insulator, depending on the number of electrons from the electric field, the New Atlas reported. The team then converted graphene into completely different states by simply altering the voltage using a knob.

Also in 2018, Jarillo-Herrero and his team altered the voltage received by the magic material via a single electrode, or what they call a metallic gate.

"Magic" Material Superconducting, Insulating and Something in-Between

In this current study, Jarillo-Herrero and his team introduced multiple gates to expose different areas of the material to a variety of electric fields, Daniel Rodan-Legrain, an MIT graduate student in physics and lead author of the paper.

The team then unexpectedly was able to adjust a variety of sections of the same magic material into several electronic states, from superconducting to inducting, to an undetermined state between the two. As they applied the gates in a variety of configurations, the researchers were able to recreate all the components of the electronic circuit that would be normally created using ordinary materials.

"Magic" Material Turned into Quantum Electronic Devices

Eventually, the team used this method to produce various quantum electronic devices. These devices include a superconducting switch called a Josephson junction. Josephson junctions serve as building blocks of quantum bits, or qubits, which is the force behind quantum computing. They also have additional applications, such as devices that measure magnetic fields.

The MIT team likewise made two other devices-a spectroscopic tunneling device, which is key to studying superconductivity, and a single-electron transistor, which is a sensitive device that manages the movement of electricity.

All these three devices benefit from being created from a single electrically tunable material.

Their work would lead to many future innovations in quantum computing. Such can be used to make the first voltage-tunable qubit from a single material that could be used in future quantum computers.