  In this study, we observe that the conductance of a quantum point contact on
a GaAs/AlGaAs double quantum well depends significantly on the magnetic field
perpendicular to the two-dimensional electron gas. In the presence of the
magnetic field, the subband edge splitting due to the Zeeman energy reaches
0.09 meV at 0.16 T, thereby suggesting an enhanced g-factor. The estimated
g-factor enhancement is 17.5 times that of the bare value. It is considered
that a low electron density and high mobility makes it possible to reach a
strong many-body interaction regime in which this type of strong enhancement in
g-factor can be observed.
