In underdoped cuprates, the interplay of the pseudogap, superconductivity, and charge and spin ordering can give rise to exotic quantum states, including the pair density wave (PDW), in which the superconducting (SC) order parameter is oscillatory in space. However, the evidence for a PDW state remains inconclusive and its broader relevance to cuprate physics is an open question. To test the interlayer frustration, the crucial component of the PDW picture, we perform transport measurements on charge- and spin-stripe-ordered La_1.7Eu_0.2Sr_0.1CuO₄ and La_1.48Nd_0.4Sr_0.12CuO₄ in perpendicular magnetic fields (H_⊥), and also with an additional field applied parallel to CuO₂ layers (H_∥). We detect several phenomena predicted to arise from the existence of a PDW, including an enhancement of interlayer SC phase coherence with increasing H_∥. These data also provide much-needed transport signatures of the PDW in the regime where superconductivity is destroyed by quantum phase fluctuations.

在欠掺杂的铜酸盐中，赝能隙、超导以及电荷和自旋有序的相互作用会产生奇异的量子态，包括对密度波 (PDW)，其中超导 (SC) 有序参数在空间中是振荡的。然而，PDW 状态的证据仍然没有定论，其与铜酸盐物理学的更广泛相关性是一个悬而未决的问题。_为了测试PDW 图片_的关键_组成部分_——层间挫折，我们在垂直_磁场（_{H ⊥})，以及平行于CuO ₂层施加的附加场( _H∥ )。我们检测到几种预测由 PDW 的存在引起的现象，包括层间 SC 相位相干性随着H _||的增加而增强。这些数据还提供了在超导性被量子相位波动破坏的情况下急需的 PDW 传输特征。