The research group led by Benjamin Lev, assistant professor of physics, has achieved the world's first magneto-optical trapping (MOT) of both the bosonic and fermionic isotopes of dsyprosium, a rare-earth (lanthanide) element possessing the largest magnetic moment, 10 Bohr magnetons.
By using a combination of Zeeman slowing, laser cooling, and strong magnetic field gradients, the researchers created and held an ensemble of approximately 5 million Dy atoms in a stable MOT. "While long thought impossible because of the complexity of the internal electronic structure of Dy, these experiments point the way to laser cooling and trapping other exotic atoms in the lanthanide series," said Lev.
The white "dot" in the center of the photograph is the cold Dy cloud. At 100 μK, the atomic gas in Lev's MOT is a million times colder than room temperature.
Experiments are underway to increase the size of the cloud to 100 million constituent atoms and to capture them in an optical tweezer.
The group hopes to achieve temperatures in the 100-nanoK range in the next 18 months, at which point the Dy atoms should form a dipolar BEC, or quantum ferrofluid, when the bosonic isotopes are trapped, or a novel quantum liquid crystal when fermionic isotopes are trapped.
Ultracold Dy atoms obtained from these MOTs may be used to investigate poorly understood, though technologically relevant, materials that do not obey standard Fermi liquid theory. Moreover, this exotic matter will form the essential core of novel devices possessing unsurpassed sensitivity and resolution for use in the microscopy of strongly correlated materials, such as high-temperature superconductors. Future applications also include exploiting Dy's telecom qubit transition for all telecom-band quantum computation.
Joining Lev in this pioneering work are graduate students Seo Ho Youn, Mingwu Lu, and Ushnish Ray.
This work is supported by the Air Force Office of Scientific Research and the National Science Foundation. The conclusions presented are those of the authors and not necessarily those of the funding agencies.