  Quantum behavior of superconducting nanowires may essentially depend on the
employed experimental setup. Here we investigate a setup that enables passing
equilibrium supercurrent across an arbitrary segment of the wire without
restricting fluctuations of its superconducting phase. The low temperature
physics of the system is determined by a combined effect of collective
sound-like plasma excitations and quantum phase slips. At $T=0$ the wire
exhibits two quantum phase transitions, both being controlled by the
dimensionless wire impedance $g$. While thicker wires with $g>16$ stay
superconducting, in thinnest wires with $g<2$ the supercurrent is totally
destroyed by quantum fluctuations. The intermediate phase with $2<g<16$ is
characterized by two different correlation lengths demonstrating
superconducting-like behavior at shorter scales combined with vanishing
superconducting response in the long scale limit.
