  We investigate the transport properties of two strongly coupled ballistic
one-dimensional (1D) wires, defined by a split-gate structure deposited on a
GaAs/AlGaAs double quantum well. Matching the widths and electron densities of
the two wires brings them into resonance, forming symmetric and antisymmetric
1D subbands separated by energy gaps that are measured to be larger than their
two-dimensional counterpart. Applying a magnetic field parallel to the wire
axes enhances wavefunction mixing at low fields, whereas at high fields the
wires become completely decoupled.
