  Five transport coefficients of the cuprate superconductor
Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+\delta}$ were measured in the normal state down
to low temperature, reached by applying a magnetic field (up to 66T) large
enough to suppress superconductivity. The electrical resistivity, Hall
coefficient, thermal conductivity, Seebeck coefficient and thermal Hall
conductivity were measured in two overdoped single crystals, with La
concentration $x = 0.2$ ($T_{\rm c}=18$K) and $x = 0.0$ ($T_{\rm c}=10$K). The
samples have dopings $p$ very close to the critical doping $p^{\star}$ where
the pseudogap phase ends. The resistivity displays a linear dependence on
temperature whose slope is consistent with Planckian dissipation. The Hall
number $n_{\rm H}$ decreases with reduced $p$, consistent with a drop in
carrier density from $n = 1+p$ above $p^{\star}$ to $n=p$ below $p^{\star}$.
This drop in $n_{\rm H}$ is concomitant with a sharp drop in the density of
states inferred from prior NMR Knight shift measurements. The thermal
conductivity satisfies the Wiedemann-Franz law, showing that the pseudogap
phase at $T = 0$ is a metal whose fermionic excitations carry heat and charge
as do conventional electrons. The Seebeck coefficient diverges logarithmically
at low temperature, a signature of quantum criticality. The thermal Hall
conductivity becomes negative at low temperature, showing that phonons are
chiral in the pseudogap phase. Given the observation of these same properties
in other, very different cuprates, our study provides strong evidence for the
universality of these five signatures of the pseudogap phase and its critical
point.
