Physicists get closer to examining the symmetries underlying our
universe

Date:
January 12, 2021
Source:
University of California - Santa Barbara
Summary:
Every field has its underlying principles. For economics it's
the rational actor; biology has the theory of evolution; modern
geology rests on the bedrock of plate tectonics.



FULL STORY ========================================================================== Every field has its underlying principles. For economics it's the rational actor; biology has the theory of evolution; modern geology rests on the
bedrock of plate tectonics.


========================================================================== Physics has conservation laws and symmetries. For instance, the law of conservation of energy -- which holds that energy can neither be created
nor destroyed -- has guided research in physics since antiquity, becoming
more formalized as time went on. Likewise, parity symmetry suggests that switching an event for its mirror image shouldn't affect the outcome.

As physicists have worked to understand the truly bizarre rules of quantum mechanics, it seems that some of these symmetries don't always hold up.

Professor Andrew Jayich focuses on investigating these symmetry violations
in an effort to shed light on new physics. He and his lab members have
just published a paper in Physical Review Letters reporting progress
on synthesizing and detecting ions that are among the most sensitive
measures for time (T) symmetry violations.

Time symmetry implies that the laws of physics look the same when time
runs forward or backward. "For example, the path of a pool ball on a
table simply retraces its course if the arrow of time is reversed,"
Jayich said. But that does not hold for all physical interactions.

Understanding when and why T symmetry breaks down could provide answers to
some of the biggest open questions in physics, such as why the Universe is
full of matter and lacks antimatter. "The laws of physics as we know them
treat matter and antimatter on equal footing," Jayich said, "yet events in
the early moments of the Universe favored matter over antimatter." These
are tough problems to crack, with close to a century of work behind them.

To address these questions, Jayich and his team have controllably
synthesized, trapped and cooled radioactive molecules, RaOCH3+ and
RaOH+, that provide large improvements in sensitivity to T symmetry
violation. First author Mingyu Fan, a doctoral student in Jayich's lab, discovered a technique to detect dark ions in their electromagnetic
trap. These particles don't scatter light, which means the researchers
can't detect them with a camera.

While adjusting some of the experimental parameters, Fan noticed the
trapped ions, which normally sit very still, were oscillating rapidly at
a large yet fixed amplitude. He figured out that this behavior provides
a strong signal for detecting these elusive ions. "This controlled amplification of the motion allows us to measure the ion's motional
frequency, and thus its mass precisely and quickly," Fan said.

Jayich and Fan reported their success in laser cooling radium ions
in a previous study, which was the first to achieve this feat for the
heavy element.

The lab's recent breakthrough brings them closer to their ultimate goal
of using radioactive molecules to test time symmetry violations.

The researchers used radium-226, which has 138 neutrons and no nuclear
spin, in their recent work. They plan to use the slightly lighter
isotope, radium-225, which has the necessary nuclear spin, in their
planned symmetry violation experiments. Other members of the lab are
working on efforts to laser cool and trap radium-225 ions and perform
optical spectroscopy on the radioactive molecules that contain it.

"These results are a clear breakthrough for our planned 'big'
experiments," said Jayich. "We have made these incredibly sensitive
detectors, where a single molecule has the sensitivity to set new limits
on T-violation. This opens up a new paradigm for measuring T-violation."

========================================================================== Story Source: Materials provided by
University_of_California_-_Santa_Barbara. Original written by Harrison
Tasoff. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. M. Fan, C. A. Holliman, X. Shi, H. Zhang,
M. W. Straus, X.

Li, S. W. Buechele, and A. M. Jayich. Optical Mass
Spectrometry of Cold RaOH and RaOCH3. Phys. Rev. Lett, 2021 DOI:
10.1103/ PhysRevLett.126.023002 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/01/210112125213.htm

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