News - UMD Physics

Norbert M. Linke Joins UMD Physics

Details: Category: Department News; Published: Wednesday, February 06 2019 15:04

Norbert M. Linke has joined the Department of Physics as an assistant professor. He has been a member of the department since 2015, first as a post-doc and then as a research scientist at the Joint Quantum Institute. Working in the group of Chris Monroe, he led a project that turned a physics experiment into a programmable quantum computer. This work helped establish trapped atomic ions as a leading contender in the quantum computing realm, and produced the first cross-platform comparison of two quantum computers in 2017.

Linke was born in Munich, Germany, and graduated from the University of Ulm, Germany. He received his doctorate at the University of Oxford, UK, working on micro-fabricated ion-traps, high-fidelity quantum gates, and microwave-addressing of ions under David Lucas.

His new group at UMD continues to work on quantum applications with trapped ions, implementing more sophisticated algorithms, but also expanding to simulations of new and unusual quantum dynamics involving the ions' motional degrees of freedom. Additionally, his lab has launched a new project to realize long-distance quantum communication using trapped ions and near-telecom photons.

Norbert Linke and his initial research team at the Joint Quantum Institute (UMD, Jan 2019). A strong representation of women is unfortunately still unusual in the STEM realm, and the group is committed to continuously improving at providing an inclusive environment.

Daniel Lathrop Comments on Earth's Changing Magnetic Poles in Phys.org Article

Details: Category: Department News; Published: Tuesday, February 05 2019 10:04

Professor Daniel Lathrop commented on the movement of Earth's magnetic poles and an eventually flipping of the poles in an article titled, "Check Your Compass: The Magnetic North Pole is on the Move" on Phys.org this week.

Glass Fibers and Light Offer New Control Over Atomic Fluorescence

Details: Category: Research News; Published: Friday, February 01 2019 14:47

Electrons inside an atom whip around the nucleus like satellites around the Earth, occupying orbits determined by quantum physics. Light can boost an electron to a different, more energetic orbit, but that high doesn’t last forever. At some point the excited electron will relax back to its original orbit, causing the atom to spontaneously emit light that scientists call fluorescence.

Scientists can play tricks with an atom’s surroundings to tweak the relaxation time for high-flying electrons, which then dictates the rate of fluorescence. In a new study, researchers at the Joint Quantum Institute observed that a tiny thread of glass, called an optical nanofiber, had a significant impact on how fast a rubidium atom releases light. The research, which appeared as an Editor’s Suggestion in Physical Review A, showed that the fluorescence depended on the shape of light used to excite the atoms when they were near the nanofiber.

“Atoms are kind of like antennas, absorbing light and emitting it back out into space, and anything sitting nearby can potentially affect this radiative process,” says Pablo Solano, the lead author on the study and a University of Maryland graduate student at the time this research was performed.

To probe how the environment affects these atomic antennas, Solano and his collaborators surround a nanofiber with a cloud of rubidium atoms. Nanofibers are custom-made conduits that allow much of the light to travel on the outside of the fiber, enhancing its interactions with atoms. The atoms closest to the nanofiber—within 200 nanometers—felt its presence the most. Some of the fluorescence from atoms in this region hit the fiber and bounced back to the atoms in an exchange that ultimately modified how long a rubidium atom’s electron stayed excited.

The researchers found that the electron lifetime and subsequent atomic emissions depended on the wave characteristics of the light. Light waves oscillate as they travel, sometimes slithering like a sidewinder snake and other times corkscrewing like a strand of DNA. The researchers saw that for certain light shapes the electron lingered in the excited state, and for others, it made a more abrupt exit.

“We were able to use the oscillation properties of light as a kind of knob to control how atomic fluorescence near the nanofiber turned on,” Solano says.

The team originally set out to measure the effects the nanofiber had on atoms, and compare the results to theoretical predictions for this system. They found disagreements between their measurements and existing models that incorporate many of the complex details of rubidium’s internal structure. This new research paints a simpler picture of the atom-fiber interactions, and the team says more research is needed to understand the discrepancies.

"We believe this work is an important step in the on-going quest for a better understanding of the interaction between light and atoms near a nanoscale light-guiding structure, such as the optical nanofiber we used here," says JQI Fellow and NIST scientist William Phillips, who is also one of the lead investigators on the study.

Written by Emily Edwards

Solano is currently a postdoctoral researcher at the MIT-Harvard University Center for Ultra Cold Atoms. In addition, the following researchers were authors on this study.

Weber Garden Dedication Held March 12

Details: Category: Department News; Published: Monday, January 28 2019 06:28

The Department of Physics and College of Mathematical and Natural Sciences held a dedication of the Weber Garden on Tuesday, March 12, 2019, which included remarks by colleagues and friends of Joe Weber and a colloquium by Nobel Laureate Rai Weiss: What Joe Weber started: Gravitational wave astronomy.

The garden, next to the main entrance of the Physical Sciences Complex, highlights the ultrapure aluminum gravity bars of UMD physicist Joseph Weber, a pioneer in the search for gravitational waves. Prof. Emeritus Charles W. Misner and his wife Susanne established the Weber Endowment for Gravitational Physics.

The 2016 announcement that the LIGO experiment had detected gravitational waves led to the Nobel Prize for Weiss, Kip Thorne and Barry Barish. UMD's key contributions in theoretical and experimental gravitational physics were discussed at a Nov. 1, 2016 symposium, A Celebration of Gravitational Waves.