Dynamical instability of the XY spiral state of ferromagnetic condensates.
We calculate the spectrum of collective excitations of the XY spiral state prepared adiabatically or suddenly from a uniform ferromagnetic F=1 condensate. For spiral wave vectors past a critical value, spin wave excitation energies become imaginary indicating a dynamical instability. We construct phase diagrams as functions of spiral wave vector and quadratic Zeeman energy.
Physics Department, Harvard University, Cambridge, Massachusetts 02138, USA.
R W
RW
Cherng
V
V
Gritsev
D M
DM
Stamper-Kurn
E
E
Demler