Wehinger Björn, Lisandrini Franco T, Kestin Noam, Bouillot Pierre, Ward Simon, Thielemann Benedikt, Bewley Robert, Boehm Martin, Biner Daniel, Krämer Karl W, Normand Bruce, Giamarchi Thierry, Kollath Corinna, Läuchli Andreas M, Rüegg Christian
Department of Quantum Matter Physics, University of Geneva, Geneva, Switzerland.
PSI Center for Neutron and Muon Sciences, Paul Scherrer Institute, Villigen-PSI, Switzerland.
Nat Commun. 2025 Apr 4;16(1):3228. doi: 10.1038/s41467-025-58380-7.
Supersymmetry is an algebraic property of a quantum Hamiltonian that, by giving every boson a fermionic superpartner and vice versa, may underpin physics beyond the Standard Model. Fractional bosonic and fermionic quasiparticles are familiar in condensed matter, as in the spin and charge excitations of the t-J model describing electron dynamics in one-dimensional materials, but this type of symmetry is almost unknown. However, the triplet excitations of a quantum spin ladder in an applied magnetic field provide a supersymmetric analogue of the t-J chain. Here we perform neutron spectroscopy on the spin-ladder compounds (CDN)CuBr and (CDN)CuCl over a range of applied fields and temperatures, and apply matrix-product-state methods to the ladder and equivalent chain models. From the momentum-resolved dynamics of a single charge-like excitation in a bath of fractional spins, we find essential differences in thermal broadening between the supersymmetric and non-supersymmetric sectors. The persistence of a strict zone-centre pole at all temperatures constitutes an observable consequence of supersymmetry that marks the beginning of supersymmetric studies in experimental condensed matter.
超对称是量子哈密顿量的一种代数性质，通过给每个玻色子一个费米子超伴子，反之亦然，它可能为超出标准模型的物理学提供基础。分数玻色子和费米子准粒子在凝聚态物质中很常见，比如在描述一维材料中电子动力学的t-J模型的自旋和电荷激发中，但这种对称性几乎不为人知。然而，在施加磁场的情况下，量子自旋梯的三重激发提供了t-J链的超对称类似物。在这里，我们在一系列施加的磁场和温度范围内对自旋梯化合物(CDN)CuBr和(CDN)CuCl进行中子光谱学研究，并将矩阵乘积态方法应用于梯模型和等效链模型。从分数自旋浴中单个类电荷激发的动量分辨动力学，我们发现超对称和非超对称部分在热展宽方面存在本质差异。在所有温度下严格的区中心极点的持续存在构成了超对称的一个可观测结果，这标志着实验凝聚态物质中超对称研究的开始。
