  We simulate the dissipative evolution of a vortex in a trapped
finite-temperature dilute-gas Bose-Einstein condensate using first-principles
open-systems theory. Simulations of the complete stochastic projected
Gross-Pitaevskii equation for a partially condensed Bose gas containing a
single quantum vortex show that the transfer of condensate energy to the
incoherent thermal component without population transfer provides an important
channel for vortex decay. For the lower temperatures considered, this effect is
significantly larger that the population transfer process underpinning the
standard theory of vortex decay, and is the dominant determinant of the vortex
lifetime. A comparison with the Zaremba-Nikuni-Griffin kinetic (two-fluid)
theory further elucidates the role of the particle transfer interaction, and
suggests the need for experimental testing of reservoir interaction theory. The
dominance of this particular energetic decay mechanism for this open quantum
system should be testable with current experimental setups, and its observation
would have broad implications for the dynamics of atomic matter waves and
experimental studies of dissipative phenomena.
