Physics at the Edge of the World

A view of Amundsen-Scott Station at the South Pole. (Credit: Dwight Bohnet/NSF)A view of Amundsen-Scott Station at the South Pole. (Credit: Dwight Bohnet/NSF)


Deep within the ice covering the South Pole, thousands of sensitive cameras strain their digital eyes in search of a faint blue glow—light that betrays the presence of high-energy neutrinos.

For this episode, Chris sat down with UMD graduate student Liz Friedman and physics professor Kara Hoffman to learn more about IceCube, the massive underground neutrino observatory located in one of the most desolate spots on Earth. It turns out that IceCube is blind to the highest-energy neutrinos, and Friedman is heading down to the South Pole to help install stations for a new observatory—the Askaryan Radio Array—which uses radio waves instead of blue light to tune into the whispers of these ghostly visitors.

This episode of Relatively Certain was produced by Chris Cesare and Emily Edwards. It features music by Dave Depper and Podington Bear. Relatively Certain is a production of the Joint Quantum Institute, a research partnership between the University of Maryland and the National Institute of Standards and Technology, and you can find it on iTunes, Google Play or Soundcloud.

New Hole-Punched Crystal Clears a Path for Quantum Light

Optical highways for light are at the heart of modern communications. But when it comes to guiding individual blips of light called photons, reliable transit is far less common. Now, a collaboration of researchers from the Joint Quantum Institute (JQI), led by JQI Fellows Mohammad Hafezi and Edo Waks, have created a photonic chip that both generates single photons, and steers them around. The device, described in the Feb. 9 issue of Science (link is external), features a way for the quantum light to seamlessly move, unaffected by certain obstacles.

Read more.

Rare Decays Provide Hints of Particle Mischief

Scientists cataloguing the disintegration of an ethereal particle may have spotted new signs of a subtle discrepancy in the Standard Model—the theory that wraps up all of particle physics in a single equation.

The new measurement, performed at the Large Hadron Collider beauty experiment (LHCb) and led by a team at UMD, adds to a growing body of evidence that appears to contradict a basic property of the Standard Model. That property, called lepton flavor universality, seems to emerge directly from the underlying mathematics, and it imposes a democratic order on three fundamental particles: Electrons, together with their heavier cousins —the muon and the tau, should behave identically during certain kinds of particle interactions.

But for several years physicists have been finding cracks in this egalitarian image. The latest result, which makes detailed use of the different ways that very rare particles decay, strengthens the case against lepton universality and may point the way toward new physics. As more rare decays are recorded, researchers could begin to mount an even stronger case and investigate other aspects of the violation.

The paper has been accepted for publication in Physical Review Letters, and a preprint is available for download on the arXiv. The CERN Courier highlighted the result this past October.

The UMD team that devised and led the measurement includes Professor Hassan Jawahery, graduate student Jack Wimberley and postdoctoral researcher Brian Hamilton.


Spheres of Attraction, Brought Together by Quantum Physics

Researchers at the University of Maryland have made new measurements of a practically imperceptible effect, known as the Casimir force. In contrast to more familiar forces like gravitation, scientists didn’t even really know of its existence until the mid 20th century.

Read more.

Narrow Glass Threads Synchronize the Light Emissions of Distant Atoms

If you holler at someone across your yard, the sound travels on the bustling movement of air molecules. But over long distances your voice needs help to reach its destination—help provided by a telephone or the Internet. Atoms don’t yell, but they can share information through light. And they also need help connecting over long distances.

Read more.