Unconventionally large quantum-dissipative gap regime in overdoped ${\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{CaCu}}_2{\mathrm{O}}_{8+y}$

We report on an unexpectedly extensive dissipative gapped regime in the zero-temperature (quantum) limit in highly overdoped ${\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{CaCu}}_2{\mathrm{O}}_{8+y}.$ Using high-field interlayer resistivity measurements we show that as $\overrightarrow{T}0$ the magnetic field that closes the pseudogap and the upper critical field $H_{c2\mathrm{}}$ coincide, uniquely defining the upper limit on the vortex state. By mapping the upper and lower bounds on the molten vortex state, we find the gapped quantum fluctuation regime stretching from $\sim 30$ to 70 T. This exceeds by far the conventional estimates, pointing to the anomalous gapped nature of the strongly overdoped regime.