Vortex formations from domain wall annihilations in two-component Bose-Einstein condensates

We theoretically study the vortex formation from the collision of the domain walls in phase-separated two-component Bose-Einstein condensates. The collision process mimics the tachyon condensation for the annihilation of D-brane and anti-D-brane in string theory. A pair annihilation leaves the quantized vortices with superflow along their core, namely superflowing cosmic strings. It is revealed that the line density and the core size of the vortices depend on the initial distance between the walls.