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A schematic drawing of how a ring of exceptional points (shown in dashes) can be spawned from a Dirac point (a dot), and thus change the dispersion from a conical shape that is widely known into an exotic lantern-like shape. (Credit: Yale)


Physicists discover ring of exotic ‘exceptional points’

Physicists have long known about the existence of unique points where two physical states coalesce into one. They call them “exceptional points.”

These points give rise to counterintuitive phenomena; a more opaque material can seem more transparent, and light may be allowed to propagate in one direction but not the other.

Now, in a paper published in the journal Nature, scientists have outlined a new concept called the “exceptional ring.”

[what are theoretical physicists actually up to?]

An exceptional ring is a continuous ring of exceptional points, and its discovery opens new avenues of research for basic science and technology, note the researchers. In this case, the exceptional rings were found in a slab of nanostructured material called a photonic crystal.

The researchers found that exceptional rings arise from Dirac cones, which commonly occur in a 2D material and have been the focus of many important physics discoveries in the past decade.

“This finding may enable a number of exciting applications,” says co-lead author Chia Wei Hsu, a Yale University postdoctoral researcher in applied physics. “Examples include more sensitive biological and chemical sensors, lasers with higher output power, and light-emitting devices with directional emission.”

The other co-lead authors of the research are Bo Zhen of MIT and Yuichi Igarashi of Smart Energy Research Laboratories in Japan.

Source: Yale University

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