About us

The Information Technology industry’s ability to shrink components to make computational devices more powerful is running into serious roadblocks. The strong influence of quantum mechanical effects takes over as device components shrink to the atomic scale. As a result, harnessing quantum effects for computation potentially offers a powerful new route to solving real world computational problems.

The Center for Quantum Nanoscience (QNS) at Ewha Womans University aims to investigate quantum effects in solid state systems to further our understanding of this crucially important, but as of yet, poorly understood basic research field. Our goal is to become recognized as the best place to perform quantum research on the atomic scale in a solid-state environment and be a destination for leading domestic and international researchers.

What is Quantum Nanoscience?

Quantum nanoscience is a novel research field at the intersection of quantum and nanoscience. Quantum science studies the quantum mechanical properties of matter and Molecular Nanoscience focuses on materials at the atomic scale. QNS combines both of these by investigating the quantum behavior of atoms and molecules on surfaces. In this endeavor, we employ specialized tools that allow us to see and touch atoms and move them into desired atomic positions. This allows us to build engineered structures consisting of several atoms.

The Center for Quantum Nanoscience focuses on a basic exploration of our world on the atomic scale with an eye towards harnessing these quantum behaviors for high-density data storage and quantum computation in the long term.
 

Our Goals

  • Achieving full control of the quantum states of atoms and molecules on clean surfaces and near interfaces
  • Exploring both theoretically and experimentally, systems and strategies for coherent manipulation of quantum nanostructures, with emphasis on understanding and mitigating decoherence
  • Demonstrating and optimizing the use of single atoms and molecules as quantum bits for quantum computation applications
  • Investigating the transition from quantum to classical behavior, including the quantum measurement problem
 

Highlights

Magnetic Resonance Imaging of Single Atoms on a Surface

Our team showed that the MRI process is possible for an individual atom on a surface using an STM. QNS scientists in an international collaboration used this new technique to visualize the magnetic field of single atoms.
The two elements that were investigated in this work, iron and titanium, are both magnetic. Through precise preparation of the sample, the atoms where readily visible in the microscope. The researchers then used the microscope’s tip like an MRI machine to map the three-dimensional magnetic field created by the atoms with unprecedented resolution. In order to do so, they attached another spin cluster to the sharp metal tip of their microscope. Similar to everyday magnets, the two spins attract or repel each other depending on their relative position. By sweeping the tip spin cluster over the atom on the surface, the researchers were able to map out the magnetic interaction.
Lead author, Dr. Philip Willke of QNS says: “It turns out that the magnetic interaction we measured depends on the properties of both spins, the one on the tip and the one on the sample. For example, the signal that we see for iron atoms is vastly different from that for titanium atoms. This allows us to distinguish different kinds of atoms by their magnetic field signature and makes our technique very powerful.”

Breakthrough in Accessing the Tiny Magnet within the Core of a Single Atom

The two elements that were investigated in this work, iron and titanium, are atoms that can have a different number of neutrons in the atom’s core, these are the so-called isotopes. Only certain isotopes of each element have a core with a nuclear spin. It is normally exceedingly hard to measure nuclear spins of individual atoms. Traditionally large numbers of nuclear spins are required, making this advancement so noteworthy.
In order to detect the presence of a nuclear spin within the core of a single atom, the team made use of the hyperfine interaction. This phenomenon describes the coupling between a single atom’s nuclear spin and its electron counterpart, that is generally much easier to access. Dr. Philip Willke of the Center for Quantum Nanoscience (QNS), first author of the study, says: “We found that the hyperfine interaction of an atom changed when we moved it to a different position on the surface or if we moved other atoms next to it. In both cases, the electronic structure of the atom changes and the nuclear spin allows us to detect that.

A step closer to single-atom data storage

Physicists of QNS and EPFL used Scanning Tunneling Microscopy to successfully test the stability of a magnet made up of a single atom. Despite the rise of solid-state drives, magnetic storage devices such as conventional hard drives and magnetic tapes are still very common. But as our data-storage needs are increasing at a rate of almost 15 million gigabytes per day, scientists are turning to alternative storage devices. One of these are single-atom magnets: storage devices consisting of individual atoms stuck (“adsorbed”) on a surface, each atom able to store a single bit of data that can be written and read using quantum mechanics. And because atoms are tiny enough to be packed together densely, single-atom storage devices promise enormous data capacities. But although they are no longer science fiction, single-atom magnets are still in basic research, with many fundamental obstacles to be overcome before they can be implemented into commercial devices. EPFL has been at the forefront of the field, overcoming the issue of magnetic remanence, and showing that single-atom magnets can be used to read and write data. Fabio Donati of the IBS Center for Quantum Nanoscience, coauthor of the publication, says that “the intriguing behavior of single-atom magnets is interesting both for fundamental science and for future applications. Exploring the limiting factors of their magnetic stability is crucial for engineering future nanoscale devices that can use single atoms as building blocks.”

One Atom Bit

One bit of digital information can now be successfully stored in an individual atom, according to a study just published in Nature. Current commercially-available magnetic memory devices require approximately one million atoms to do the same. Andreas Heinrich, newly appointed Director of the Center for Quantum Nanoscience, within the Institute of Basic Science (IBS, South Korea), led the research effort that made this discovery at IBM Almaden Research Center (USA). This result is a breakthrough in the miniaturization of storage media and has the potential to serve as a basis for quantum computing.

A Quantum Sensor Made from Individual Iron Atoms

QNS researchers, in collaboration with a team of IBM researchers in the USA have succeeded in using individual iron atoms as quantum sensors. Using this sensor, they were able to measure the small magnetic field created by neighboring magnetic atoms, an effect that was previously not measurable in scanning tunneling microscopy.
This work is the first application of a recent breakthrough invention of the same team, which demonstrated electron spin resonance – a quantum mechanical measurement of single spins – in the STM. “We believe that this quantum sensor can be used to measure the spins in complex molecules with atomic-scale spatial resolution, sort of like a nano-GPS”, suggests Taeyoung Choi, first author of the recent study.
 

QNS at Glance

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