We report current transmission data through a split-gate constriction
fabricated onto a two-dimensional electron system in the integer quantum Hall
(QH) regime. Split-gate biasing drives inter-edge backscattering and is shown
to lead to suppressed or enhanced transmission, in marked contrast with the
expected linear Fermi-liquid behavior. This evolution is described in terms of
particle-hole symmetry and allows us to conclude that an unexpected class of
gate-controlled particle-hole-symmetric chiral Luttinger Liquids (CLLs) can
exist at the edges of our QH circuit. These results highlight the role of
particle-hole symmetry on the properties of CLL edge states.Comment: 4 pages, 4 figure