Chaitanya Murthy

Existing quantum Hall interferometers measure twice the braiding phase, e^{i2θ}, of Abelian anyons, i.e., the phase accrued when one quasiparticle encircles another clockwise. We propose a modified Fabry-Pérot or Mach-Zehnder interferometer that can measure e^{iθ}.

Inspired by the observation of increasingly one-dimensional (1D) behavior with decreasing temperature in small-angle twisted bilayers of WTe_{2} (tWTe_{2}), we theoretically explore the exotic sliding regimes that could be realized in tWTe_{2}. At zero displacement field, while hole-doped tWTe_{2} can be thought of as an array of weakly coupled conventional two-flavor 1D electron gases (1DEGs), the electron-doped regime is equivalent to coupled four-flavor 1DEGs, due to the presence of an additional "valley" degree of freedom. In the decoupled limit, the electron-doped system can thus realize phases with a range of interesting ordering tendencies, including 4k_{F} charge-density-wave and charge-4e superconductivity. Dimensional crossovers and cross-wire transport due to interwire couplings of various kinds are also discussed. We find that a sliding Luther-Emery liquid with small interwire couplings is probably most consistent with current experiments on hole-doped tWTe_{2}.

The occurrence of superconductivity in proximity to various strongly correlated phases of matter has drawn extensive focus on their normal state properties, to develop an understanding of the state from which superconductivity emerges^1,2,3,4. The recent finding of superconductivity in layered nickelates raises similar interests^5,6,7,8. However, transport measurements of doped infinite-layer nickelate thin films have been hampered by materials limitations of these metastable compounds: in particular, a high density of extended defects^9,10,11. Here, by moving to a substrate (LaAlO₃)_0.3(Sr₂TaAlO₆)_0.7 that better stabilizes the growth and reduction conditions, we can synthesize the doping series of Nd_1–xSr_xNiO₂ essentially free from extended defects. In their absence, the normal state resistivity shows a low-temperature upturn in the underdoped regime, linear behaviour near optimal doping and quadratic temperature dependence for overdoping. This is phenomenologically similar to the copper oxides^2,12 despite key distinctions—namely, the absence of an insulating parent compound^5,6,9,10, multiband electronic structure^13,14 and a Mott–Hubbard orbital alignment rather than the charge-transfer insulator of the copper oxides^15,16. We further observe an enhancement of superconductivity, both in terms of transition temperature and range of doping. These results indicate a convergence in the electronic properties of both superconducting families as the scale of disorder in the nickelates is reduced.