Researchers from the Cavendish Laboratory have modelled a quantum walk of identical particles that can change their fundamental character by simply hopping across a domain wall in a one-dimensional lattice.
Their findings, published as a Letter in Physical Review Research, open up a window to engineer and control new kinds of collective motion in the quantum world.
All known fundamental particles fall in two groups: either a fermion ("matter particle") or a boson ("force carrier"), depending on how their state is affected when two particles are exchanged. This "exchange statistics" strongly affects their behaviour, with fermions (electrons) giving rise to the periodic table of elements and bosons (photons) leading to electromagnetic radiation, energy and light.
In this new study, the theoretical physicists show that, by applying an effective magnetic field that varies in space and with the particle density, it is possible to coax the same particles to behave as bosons in one region and (pseudo)fermions in another. The boundaries separating these regions are invisible to every single particle and, yet, dramatically alters their collective motion, leading to striking phenomena such as particles getting trapped or fragmenting into many wave packets.
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