  When the intensity of turbulence is increased (by increasing the Reynolds
number, e.g. by reducing the viscosity of the fluid), the rate of the
dissipation of kinetic energy decreases but does not tend asymptotically to
zero: it levels off to a non-zero constant as smaller and smaller vortical flow
structures are generated. This fundamental property, called the dissipation
anomaly, is sometimes referred to as the zeroth law of turbulence. The question
of what happens in the limit of vanishing viscosity (purely hypothetical in
classical fluids) acquires a particular physical significance in the context of
liquid helium, a quantum fluid which becomes effectively inviscid at low
temperatures achievable in the laboratory. By performing numerical simulations
and identifying the superfluid Reynolds number, here we show evidence for a
superfluid analog to the classical dissipation anomaly. Our numerics indeed
show that as the superfluid Reynolds number increases, smaller and smaller
structures are generated on the quantized vortex lines on which the superfluid
vorticity is confined, balancing the effect of weaker and weaker dissipation.
