Supersymmetry is symmetry of nature that is often hypothesized to exist
among elementary particles. In a new paper that appeared in Physical Review
Letters this week, physicists from the University of Amsterdam and QuSoft
propose a setup where supersymmetry can also be observed between lumps of
energy in a material—so-called kinks and skinks.
Supersymmetry—a physicist's tool
Supersymmetry is a hypothesized symmetry of nature which connects the known
types of elementary particles to different but very similar particles: their
'superpartners." Inspired by the beauty of this idea, condensed matter
physicists have proposed to use supersymmetry to help address some of the
hard problems, such as the behavior of large groups of strongly interacting
quantum particles, where often numerical approaches, though limited, are the
only option.
This is in particular the case for interacting electrons in solid state
systems, which underlie some outstanding questions. A good example is the
question why and when some materials, at relatively high temperatures, can
completely lose their resistance to electric currents and become
superconductors.
To answer such questions, physicists have designed theoretical models which
explicitly include supersymmetry. Their quest is to understand the quantum
states of matter formed by fermions, a family of particles with similar
properties to the electron. A particularly natural proposal was made in 2003
in two consecutive papers by UvA-physicists Kareljan Schoutens, Jan de Boer
and Bernard Nienhuis together with Paul Fendley (now in Oxford).
Kinks and skinks
Importantly, the above considerations so far remained the playground of
theorists. However, in their new paper, Jiřà Minář, Bart van Voorden and
Kareljan Schoutens propose, for the first time, how to also possibly realize
such supersymmetric systems in a laboratory, using neutral atoms cooled down
to a temperature close to absolute zero, more than 270 degrees below zero on
the Celsius scale. The atoms are manipulated by lasers, bringing them in a
highly excited state, the so-calledRydberg state, which helps mediate the
interaction between the atoms. Such Rydberg atom systems are now commonly
used in laboratories (including labs at the University of Amsterdam and TU
Eindhoven), among other things because they constitute one of the
frontrunner platforms for the realization of a quantum computer.
The system studied in the new paper features 'topological quasiparticle
excitations'—localized lumps of energy known as kinks, as well as their
superpartners dictated by the supersymmetry—the skinks. The researchers were
able to design an explicit experimental protocol which prepares and detects
the dynamics of both kinks and skinks. The remarkable feature of their setup
is that the way the measured quantities evolve in time is identical for both
kinks and skinks. This gives a clear experimental sign of the fact that
these quasi-particles are indeed very similar—that is, it shows the
underlying supersymmetry.
Toward more dimensions
The new research focused on the simplest possible scenario—a one-dimensional
lattice where the atoms are all arranged on a line. The work may therefore
inspire not only possible experimental realizations of supersymmetry using
available techniques, but also the design of more elaborate simulators of
supersymmetric models in more than one dimension—with the atoms arranged in
a two-dimensional plane, or even in all three directions. Such systems are
known to exhibit exquisite properties, the nature of which still remains
poorly understood. A Rydberg atom quantum simulator might provide the right
tool to address such intriguing questions in the future.
Reference:
Jiřà Minář et al, Kink Dynamics and Quantum Simulation of Supersymmetric
Lattice Hamiltonians, Physical Review Letters (2022).
DOI: 10.1103/PhysRevLett.128.050504
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Physics