A mechanism of memories, especially biological memories, is studied in terms of quantum fluids. Two-dimensional flows in central potentials Va(ρ)=−a2gaρ2(a−1)
Nearby in the stack
(
a=0
and
ρ=x2+y2
) have zero-energy eigenstates that degenerate infinitely for all
a
. It is shown that stable standing waves constructed from the zero-energy flows are confined in various types of polygons which can be the minimum units of memory systems. Vortex patterns awoken in the units by stimuli correspond to the memories of the stimuli. This memory system is not a system for preserving memories as usual but that for awaking memories. The system has interesting properties; (i) the absolute economy as for the energy consumption, (ii) the infinite variety for a huge number of memories, (iii) the perfect recovery of the system from any disturbances by stimuli, and (iv) the large flexibility in the construction of the system. A process for thinking is also proposed in terms of this memory system.