Fig. 4: Superfluid fraction from Josephson oscillations.
From: Measurement of the superfluid fraction of a supersolid by Josephson effect
a, Superfluid fraction as a function of εdd. Black dots are experimental results derived from the Josephson frequencies. Vertical error bars result from the error propagation of equation (3), with K = ωJ2/(4UN34); see Methods. Green dots are results from numerical simulations. Error bars are the uncertainties of the linear fits used to determine K and UN34. Pink points are derived from the experimental phase–current relation, as in c. Error bars are estimated using the propagation of equation (3), with K and its relative uncertainty extracted from linear fits of experimental data. The open pink point at εdd = 1.444 is the dataset without the optical-separation technique (Methods). The grey band extends between the upper and lower bounds of equation (1). b,c, Phase–current relation at εdd = 1.444. The points show the results of numerical simulations (b) and experimental measurements (c). From the linear regressions (green and pink lines), we extract the coupling energy K according to equation (4a). Shaded regions are the confidence bands for one s.d.
