Supplementary Information Tonks-Girardeau gas in an optical lattice – B. Paredes, A. Widera et al. Supplementary Figure 1 Momentum profiles of the one-dimensional quantum gases for different axial lattice depths a-l. The experimental data (blue dots) are displayed together with our theoretical predictions for a fermionized gas (black line), an ideal Bose gas (green dotted line) and an ideal Fermi gas (yellow dashed line). In order to emphasize the linear part of the momentum profiles an auxiliary straight line with the corresponding slope is shown in each plot. For all plots an atomic distribution characterized by an atom number N0,0 =18 in the central tube is assumed (see methods). The temperatures for the Tonks and ideal Fermi gas have been obtained in the same way as for Fig. 3 (see text). The temperatures for the ideal Bose gas have been derived again assuming conservation of entropy for increasing axial lattice depths. In this case, the initial temperature at Vax=0 has been obtained using an ideal Bose gas fit to low momenta for this momentum profile, where the ideal Bose gas is a good description of the system. In plot d the momentum profiles for the ideal Bose gas (green lines) are also displayed for different temperatures and particle numbers in the central tube of kBT/J=3.7, N0,0 =16 (dash-dotted green line) and kBT/J =0.75, N0,0 =20 (dashed green line). The lattice depths and the slopes of the linear part of the momentum profiles are summarized in the table below together with the calculated temperatures for a Tonks gas, an ideal Fermi gas and an ideal Bose gas. Figure Lattice depth Slope Tonks and Ideal Fermi Gas (kbT/J) (Er) a b c d e f g h i j k l 4.6 5.6 6.5 7.4 8.3 9.3 10.2 11.1 12.0 12.9 13.9 18.5 Ideal Bose Gas (kbT/J) 1.9 1.73 1.58 1.44 1.31 1.17 1.05 0.95 0.84 0.75 0.66 0.59 0.5 0.56 0.62 0.69 0.77 0.87 0.99 1.13 1.29 1.49 1.76 3.93 1.1 1.25 1.41 1.58 1.77 2.02 2.27 2.56 2.90 3.29 3.82 8.0