Capable of Saving 500,000 Movies

The diagram A shows two holmium atoms above and an iron atom on the bottom. Depending on the spin of two holmium atoms, the ESR of an iron atom can change as shown in a diagram B.
The diagram A shows two holmium atoms above and an iron atom on the bottom. Depending on the spin of two holmium atoms, the ESR of an iron atom can change as shown in a diagram B.

 

South Korean researchers succeeded in storing one bit of digital information in an individual atom. This breakthrough is expected to change the technology paradigm in the semiconductor sector which reached the limit of integration degree.

Andreas Heinrich, the head of Center for Quantum Nano Science at the Institute for Basic Science (IBS), announced on March 9 that the research team has succeeded in stably writing and reading 1 bit, the minimum amount of information required for digital signal, in a single holmium atom.

The current memory chips on the market, which are designed to express two types of magnetic atoms into 0 and 1, require around 100,000 atoms to implement 1 bit. The latest study showed that the team used a single atom as a single bit and it is theoretically proved as the smallest memory unit to store information. When developing a storage device based on the findings, 500,000 movies can be saved in a single USB memory chip because its integration will be improved by 1,000 times compared to existing hard disk drives (HDDs).

A holmium atom placed on a magnesium oxide plate will have a spin transition of up or down. The spin is a magnetic field outside caused by magnetism inside of atoms. It has a clear signal depending on the direction so it can implement 1 bit by replacing it with digital signals of 0 and 1. The study proved that the magnetic orientation of holmium atoms can be changed to desired states by applying a proper electric pulse.

The study’s co-author Choi Tae-young, a researcher at the IBS, said, “This study proved the theory that an atom can stably maintain the magnetic state. Holmium atoms don’t affect one another even when they are 10nm apart. So, it is possible to densely arrange the atoms and significantly improve the storage density.”

The research team placed an iron atom next to holmium atoms as a magnetic sensor to read the spin. The magnetic force created by holmium magnetizes an iron atom in the opposite direction. When measuring the electron spin resonance (ESR) of an iron atom, it is possible to detect the spin of holmium atoms. The team also succeeded in distinguishing and reading a total of four states made by two holmium atoms with an iron atom. The measure to read digital signal by detecting a magnetic field created by atoms is similar with the way how current commercial hard disks read information.

Heinrich said, “Our next goals are to find out why holmium atoms rarely affect the direction of spins even when they are clustered together unlike existing common sense, and conduct the study, which was carried out at an extremely low temperature of 271.5 degrees below zero, at a higher temperature again. When we develop technology to control the quantum state in where two spins co-exist through additional research, we will be able to create “Qubit” through quantum computing.”

The latest study has been continued by Heinrich since he worked at IBM and joined the Center for Quantum Nano Science at the IBS in January this year. The findings were published online in the journal Nature.

 

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