A large number of well-separated quantum vortices with positive and negative circulations behave as an inviscid fluid on large scales. The emergent collective dynamics of this vortex fluid is described by two hydrodynamical velocities introduced via vortex number current and vortex change current. The velocity field associated with the vortex number current evolves according to a hydrodynamic equation, subject to an anomalous stress absent from Euler's equation. In contrast to the chiral vortex fluid containing only like-sign vortices [1], the binary vortex fluid is compressible and the orbital angular momentum is not conserved, as characterized by an asymmetric Cauchy stress tensor [2]. Dissipation effects due to thermal friction and vortex-sound interactions are also considered.

[1] P. Wiegmann and A. G. Abanov, Phys. Rev. Lett. 113, 034501(2014).
[2] X. Yu, A. S. Bradley, arXiv:1704.05410 (2017).

Dr. Xiaoquan Yu received his PhD degree from International School for Advanced Studies (SISSA) in 2012. He is a research fellow at Department of Physics in University of Otago, New Zealand. His current research interests include collective dynamics of quantum vortices in two-dimensions, quantum turbulence, vortex-particle duality, and spinor Bose-Einstein condensates.