Quantum materials offer many advantages for the future of electronic devices, from batteries to sensors and even our smartphones. Thanks to quantum behaviors such as entanglement, these materials exhibit unusual electronic, optical and magnetic properties, making them more energy efficiency.
“By outperforming conventional materials for certain electronic processes, quantum materials open up enormous application possibilities,” says Carmine Ortix, associate professor of physics at the University of Salerno in Italy.
Electronic properties of quantum materials
Ortix is part of an international research team led by the University of Geneva that is studying how the electronic properties of quantum materials can be controlled. Their recent research shows that we can create tighter electronic control by bending the fabric of space in these materials.
The researchers wrapped their quantum material in insulators, trapping electrons – which control the output of energy – in a sandwich layer and limiting their free space. Then, using specific laser pulses, the team stacked each atom of their material on top of each other.
The results published in Natural materials, show that this new material could boost the future of energy-efficient electronics.
Read more: Why Quantum Mechanics Still Trips Physicists
What are Berry Phases?
To figure out how to control the electron’s motions, Ortix and the rest of his team relied on a concept in quantum physics known as Berry phase. Named after the English physicist Sir Michael Berry, this phase occurs when a wave-like particle (such as an electron) moves in a closed loop through a magnetic field or other force field.
As the particle moves through the loop, part of its wave function—a “map” of where the particle might be in a general region of the quantum realm—changes, affecting how it behaves around other particles.
Berry’s phase is quite complex, so it may help to imagine the process as an eye exam: the giant metal hat (a lens meter), that an ophthalmologist used to test your near and far vision, contains two focus wheels for each lens.
As the eye doctor spins these wheels, asking “Is one or two better?”, the quality of the lenses changes. When you go back to the beginning of the wheel, the difference between the first lens and the last lens is quite different.
This looping process is similar to what happens during the Berry phase, where the electron evolves as the object moves through a loop (or wheel). But Ortix and his colleagues took the Berry phase a step further in their experiment by studying the Berry curve of the electrons in their material.
Two types of Berry distortion
“You can think of Take a curve as an effective magnetic field generated by electrons when they have some special properties,” Ortix says.
Previous studies have shown that these electron curves are either spin or orbital. A spin-induced Berry curve can be drawn to show how an electron’s momentum changes as it moves through a material in the presence of a magnetic field.
The curve is called a “spin-source” because it takes into account the spin of the electron, or the quantum property that gives the electron a magnetic moment, magnetizing it. The presence of a magnetic field causes the electron to spin in the same direction as the field.
In contrast, the Berry curve with an orbital source shows the changes in the wave function of the electron without a magnetic field.
This curve looks at the orbital properties of the electron, which describe its spatial distribution around the nucleus of the atom. An electron’s orbitals can affect the phase of its wave function, influencing its behavior in the material.
Read more: The electrons “split” into a new form of matter
Electronic sandwich
In their new study, the researchers found that by bending the space where the electrons reside and simultaneously changing the material’s magnetic fields, the electrons can exhibit both spin and orbital Berry curves.
“The curvature of quantum materials is an intrinsic property of elementary electrons,” says Ortix. “In effect, the large number of electrons inside the material form a ‘quantum geometric space’ that can possess curvature.”
This means that by trapping the electrons in the specified space, scientists can more easily control when and how the electrons distort the fabric of space in the material. The two curves working in tandem allow the material to be more tightly controlled, suggesting a more energy-efficient future for our devices as it exhibits less energy loss.
Read more: Do atoms ever touch?
Energy efficient technology
“This potential needs to be explored with further experiments,” says Andrea Caviglia, a professor at the University of Geneva and co-author of the study. This new quantum material could also prove key to the future of nanotechnology and the sensing of electromagnetic signals.
Ortix explains that “the significance of these results lies in the fact that the measured properties of quantum transport can be used in the future optoelectronic nanodevices.” Examples of these types of non-nanoscale devices include solar cells or LED lights.
“The nonlinear electrical responses discussed in our study may be relevant to the creation[ing] microscale devices that convert electromagnetic energy into usable electrical energy,” adds Ortix.
The conversion of electromagnetic energy into electrical energy can be particularly useful in the telecommunications industry, where electromagnetic signals are constantly transmitted and received by telephones, laptops or television satellites.
As the telecommunications industry advances, the availability of quantum materials like those studied by Ortix and Caviglia could become vital to the creation of more powerful satellites and other devices.
Read more: The quantum internet will blow your mind. This is what it will look like