  There is currently intensive research into creating a large-scale quantum
computer with trapped ions. It is well known that for a linear ion crystal in a
harmonic potential, the ions near the center are more closely spaced compared
to the ions near the ends. This is problematic as the number of ions increases.
Here, we consider a linear ion crystal in an anharmonic potential that is
purely quartic in position. We find that the ions are more evenly spaced
compared to the harmonic case. We develop a variational approach to calculate
the properties of the ground state. We also characterize the zigzag transition
in an anharmonic potential.
