to be quite general. Binary condensates can be constructed from a wide variety of mixtures, such as by combining different elements, isotopes, hyperfine states, or even spin states. To realize enhanced quantum spin fluctuations, the key ingredients are for both components to be miscible while, at the same time, $g_{12}>\sqrt{g_{11}g_{22}}$. This is possible if the immiscibility critical point is shifted higher than the thermodynamic-limit prediction $g_{12}^{\rm c,TD} = \sqrt{g_{11}g_{22}}$ (recall Fig. \[Fig:PhaseD\]). Our proposal relies on achieving this by enhancing the role of quantum pressure.

To give a flavor for the different kinds of experimental regimes that could realize enhanced quantum spin fluctuations, consider $^{87}$Rb, for which a mixture can be constructed from the hyperfine states $|F,m_F\rangle=|2,-1\rangle$ and $|1,1\rangle$. For these, there is a Feshbach resonance that can control the interspecies scattering length [@Nicklas2015; @Widera2004; @Erhard2004; @Gross2010]. Let us then take $g=8$ as a representative example for the results in this paper. Since the intraspecies scattering lengths are $a_{11}=a_{22}=100a_0$, then choosing a trap with frequencies $\{\omega_\rho,\omega_z\}=2\pi\times\{1,10\}$ Hz would correspond to $N_\alpha=1030$ atoms per component.

To increase the atom number, one can consider species with smaller scattering lengths and/or masses. Furthermore, it is not necessary for both intraspecies scattering lengths, or 