By using electron spin qubits to control nuclear spins in a two-dimensional material, researchers atPurdue University have opened a new frontier in quantum science and technology, enabling applications like atomic-scale nuclear magnetic resonance spectroscopy, and to read and write quantum information with nuclear spins in 2D materials.
The first experimental control of nuclear spin qubits in ultrathin hexagonal boron nitride was achieved by using electron spin qubits as atomic-scale sensors.
"This is the first work showing optical initialization and coherent control of nuclear spins in 2D materials," said corresponding author Tongcang Li, a professor of physics and astronomy and electrical and computer engineering.
Light can be used to create nuclear spins and with that control, we can write and read quantum information. The method can be used in many different ways.
The qubit is a classical computer bit. It's usually built with a photon instead of a transistor. An electron or nuclear spin qubit has a familiar state of a classical computer bit that is represented by spin, a property that is similar to magnetic polarity. The spin needs to be controlled and coherent in order to perform a task.
The spin qubit can be used in a variety of ways. In the range of 10– 100 nanometers, electron trapped in the defects of 3D diamond crystals have produced image and sensor resolution.
Even higher resolution and stronger signal can be offered by qubits embedded in single layer materials. The first electron spin qubit in hexagonal boron nitride, which can exist in a single layer, was built in 2019. There is a path to controlling the nuclear spin of the nitrogen atoms surrounding each electron spin qubit.
This work was done by Li and his team in ultra thin hexagonal boron nitrides.
The spins can be set to a known spin. Radio frequencies can be used to change the nuclear spin qubit or to measure changes in the nuclear spin qubits. Their method harnesses three nitrogen nuclei at a time with longer coherence times than those of electron qubits. A built-in sensor can be created using the 2D material.
Large-scale quantum simulation can be done with a 2D nuclear spin lattice. At higher temperatures, it can work.
Researchers replaced a boron atom with an electron in order to control a nuclear spin qubit. The electron is in the center of nitrogen. Each nitrogen nucleus is in a random spin state.
The spin of the nitrogen nucleus is unaffected by the spin of the electron.
A change in the spin of the nucleus is caused by an interaction between the excited electron and three nitrogen nuclei. The nucleus's spin reaches the +2 state when the cycle is repeated multiple times. They can be used as a trio of qubits.
At Purdue, Li was joined by many other people.
The "Nuclear spin polarization and control in hexagonal boron nitride" is in Nature Materials.
More information: Tongcang Li, Nuclear spin polarization and control in hexagonal boron nitride, Nature Materials (2022). DOI: 10.1038/s41563-022-01329-8. www.nature.com/articles/s41563-022-01329-8 Journal information: Nature Materials
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