ABSTRACT
Superfluidity is the phenomenon of matter flow-referred to as a superflowwithout any resistance from the walls or other obstacles. It is common to refer to superfluidity as a macroscopic quantum phenomenon. The word “quantum” here is only conditionally correct. Furthermore, it is somewhat confusing since it creates an impression that superfluidity cannot exist within the domain of classical physics. It is unquestionably true that the system of classical particles cannot support a superflow, and it is from that classical-particle perspective that superfluidity is associated with the quantum world. However, it turns out that for certain complex-valued classical fields, the superfluid phenomenon is absolutely natural. Hence, superfluidity looks quantum only from either the classical-particle or quantum-field point of view, while being classical from the complementary perspective. In general, this is reflective of the dual nature of quantum fields, which under certain conditions can mimic the behavior of purely classical particles, while under other conditions can also behave as classical fields.
