Physicists have created a new ultra-thin two-layer material with quantum properties that usually requires rare earth compounds. This material, which is relatively easy to manufacture and does not contain rare earth metals, could provide a new platform for quantum computation and promote research into unconventional superconductivity and quantum criticality.
The researchers showed that starting from seemingly ordinary materials, a radically new quantum state of matter can emerge. The discovery arose from their efforts to create a quantum spin fluid that they could use to investigate new quantum phenomena such as gauge theory. This involves the production of a single layer of atomically thin tantalum disulfide, but the process also creates islands consisting of two layers.
When the team examined these islands, they found that interactions between the two layers induced a phenomenon known as the Kondo effect, leading to a macroscopically entangled state of matter that produced a heavy fermentation system.
The condo effect is an interaction between magnetic impurities and electrons that causes the electrical resistance of a material to change with temperature. This results in the electrons behaving as if they have more mass, leading to these compounds being called heavy fermion materials. This phenomenon is a hallmark of materials that contain rare earth elements.
Heavy fermion materials are important in several areas of cutting-edge physics, including research into quantum materials. “Studying complex quantum materials is hindered by the properties of naturally occurring compounds. Our goal is to produce artificial designer materials that can be easily tuned and controlled externally to expand the range of exotic phenomena that can be realized in the laboratory,” says Professor Peter Liljeroth.
For example, heavy fermion materials could act as topological superconductors, which could be useful for building qubits that are more robust to noise and interference from the environment, reducing error rates in quantum computers. “Creating this in real life would benefit enormously by having a heavy fermion material system that can be easily incorporated into electrical devices and tuned externally,” explains Viliam Vaňo, a doctoral student in Liljeroth’s group and the paper’s lead author.
Although both layers of the new material are tantalum sulfide, there are subtle but important differences in their properties. One layer behaves like a metal that conducts electrons, while the other layer has a structural change that causes electrons to be located in a regular lattice. The combination of the two results in the emergence of heavy fermion physics, which neither layer exhibits alone.
This new heavy fermion material also offers a powerful tool for studying quantum criticality. “The material can reach a quantum critical point when it begins to move from one collective quantum state to another, for example from an ordinary magnet towards a tangled heavy fermion material,” explains Professor Jose Lado. “Between these states, the whole system is critical, it responds strongly to the slightest change and provides an ideal platform for constructing even more exotic quantum matter.”
“In the future, we will investigate how the system responds to the rotation of each sheet relative to the other and try to modify the coupling between the layers to tune the material against quantum-critical behavior,” says Liljeroth.
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Peter Liljeroth, Artificial heavy fermions in a van der Waals heterostructure, Nature (2021). DOI: 10.1038 / s41586-021-04021-0. www.nature.com/articles/s41586-021-04021-0
Provided by Aalto University
Citation: A new artificial material mimics quantum entangled rare earth compounds (2021, 24 November) retrieved 25 November 2021 from https://phys.org/news/2021-11-artificial-material-mimics-quantum-entangled-rare.html
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