  The bound states of two identical dipoles in a harmonic waveguide are
investigated. In the regime of weak dipole-dipole interactions, the local frame
transformation (LFT) method is applied to determine the spectrum of dipolar
confinement-induced bound states analytically. The accuracy of the LFT approach
is discussed by comparing the analytical results with the numerical ones based
on a solution of the close-coupling equations. It is found that close to the
threshold energy in the waveguide, the LFT method needs to include more partial
wave states to obtain accurate bound state energies. As the binding energy
increases, the LFT method using a single partial wave state becomes more
accurate. We also compare the bound states in waveguides and in free space. For
the bosonic case, the s-wave dominated bound state looks like a free-space
state when its energy is below a certain value. For the fermionic case, the
p-wave dominated bound state energies in waveguides and in free-space coincide
even close to zero energy.
