Fig. 2: Hole pairing in mixD versus standard ladders.
From: Magnetically mediated hole pairing in fermionic ladders of ultracold atoms
a, Hole–hole correlator \({g}_{{\rm{h}}}^{(2)}(d,1)\) between sites on opposite legs (as illustrated in the inset) for mixD (blue) and standard (brown) ladders with two to four holes per ladder. The strong correlation at d = 0 corresponds to two holes on the same rung. Correlations at this distance are strongly enhanced in the mixD system (pairing) and strongly suppressed in the standard ladders (repulsion). The blue line is calculated using MPS at finite temperature kBT = 0.8 J⊥ and corrected by the experimental detection fidelity (Methods). b, Excess events δh(d) of the same data, that is, the likelihood of finding holes at distance d compared with the infinite-temperature distribution. c, Hole–hole correlation on the same leg \({g}_{{\rm{h}}}^{(2)}(d,0)\) in the mixD system, showing that holes repel each other within the same leg. A finite-size offset correction has been applied to this subfigure (Methods). d, Spin–spin correlations C(0, 1) for spins on the same rung depending on the number of holes in the system. The lines represent linear fits. The larger slope indicates that the spin order of the standard system (brown) is more strongly disturbed by holes than the spin order of the mixD system (blue), where paired holes leave the spin order largely unperturbed. The error bars denote one s.e.m. and are smaller than the marker when not visible. Error bars in a, c and d are estimated using bootstrapping.
