We are all used to the idea that simpler units in nature interact to form
complex structures. Take, for example, the hierarchy of life, where atoms
combine to form molecules, molecules combine to form cells, cells combine to
form tissues, and so on, ultimately leading to the formation of complex
organisms such as humans. In the quantum world, however, this process may
play in reverse, where interactions between two complex objects lead to the
emergence of simpler species.
All elementary particles have a "spin," a fundamental property that governs
their interaction with magnetic fields. Spins are quantized, which means
they can only assume discrete values. Electrons have the smallest possible
spin that can take two discrete values, while the next simplest systems are
those whose spin takes three discrete values—these are dubbed spin ½ and
spin 1, respectively. In the 1980s, it was predicted that a one-dimensional
chain of interacting spin 1 units should be 'fractionalized," such that the
terminal units of the chain behave, counterintuitively, like spin ½ objects.
Therefore, much like magicians who seem to saw a person in two halves and
pull them apart, quantum correlations in the chain divide a spin 1 in two
spin ½ entities.
One-dimensional magnetic chains assembled from molecules
Testing this prediction in a laboratory has been challenging for various
reasons, chief among them being that conventional materials are not
one-dimensional. While indirect evidence of spin fractionalization has been
seen in crystals of organometallic chains containing transition metal ions,
a direct observation of the phenomenon has remained elusive.
Now, an international team of researchers has found a remarkable route to
accomplish this feat. Combining organic chemistry and ultra-high vacuum
surface science, the team fabricated chains of a triangular polycyclic
aromatic hydrocarbon with spin 1, known as triangulene. Using a scanning
tunneling microscope the team then probed magnetic excitations of these spin
chains on a gold surface. They found that beyond a certain length, the
terminal triangulene units of the chains exhibited Kondo resonances—which
are a characteristic spectroscopic fingerprint of spin ½ quantum objects in
contact with a metal surface.
The researchers believe that easily and directly accessible molecular spin
systems exhibiting strongly correlated behavior of electrons will become a
fertile playground for developing and testing new theoretical concepts. In
addition to exploring linear spin chains, the scientists are also focusing
on two-dimensional networks of quantum magnets. Such spin networks are a
promising material platform for quantum computation.
Reference:
Shantanu Mishra et al, Observation of fractional edge excitations in
nanographene spin chains, Nature (2021).
DOI: 10.1038/s41586-021-03842-3
Tags:
Physics
This may have answered a few questions I had due to my lack of specifics of scientific knowledge, I commented on magnetic gravitational forces are anti-gravity post on Facebook as I believe our concept of flight is using propulsion is all wrong and that creating a magnetic field such like our planet and our solar system and atoms are sustained in our universe would be the way to go when it comes to flying or better yet holding yourself from point to point in a craft as you would generate magnetic field and dampen One direction or the other and travel in any direction and there's no telling what the limit and speeds that could be achieved without experience G Force
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