A quantum spin-$\frac{1}{2}$ chain with an axial symmetry is normally described by quasiparticles associated with the spins oriented along the axis of rotation. Kinetic constraints can enrich such a description by setting apart different species of quasiparticles, which can get stuck at high enough density, realizing the quantum analog of jamming. We identify a family of interactions satisfying simple kinetic constraints and consider generic translationally invariant models built up from them. We study dynamics following a local unjamming perturbation in a jammed state. We show that they can be mapped into dynamics of ordinary unconstrained systems, but the nonlocality of the mapping changes the scales at which the phenomena manifest themselves. Scattering of quasiparticles, formation of bound states, and eigenstate localization become all visible at macroscopic scales. Depending on whether a symmetry is present or not, the microscopic details of the jammed state turn out to have either a marginal or a strong effect. In the former case or when the initial state is almost homogeneous, we show that even a product state is turned into a macroscopic quantum state.

中文翻译：

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量子干扰将量子力学带到宏观尺度

量子自旋——$\frac{1}{2}$具有轴对称性的链通常由与沿旋转轴定向的自旋相关的准粒子来描述。动力学约束可以通过区分不同种类的准粒子来丰富这种描述，这些准粒子可以被卡在足够高的密度上，从而实现干扰的量子模拟。我们确定了满足简单动力学约束的一系列相互作用，并考虑从它们建立的通用平移不变模型。我们研究受干扰状态下局部无干扰扰动后的动力学。我们证明它们可以映射到普通无约束系统的动力学中，但是映射的非定域性改变了现象表现本身的尺度。准粒子的散射、束缚态的形成和本征态局域化在宏观尺度上都变得可见。根据是否存在对称性，堵塞状态的微观细节会产生边际效应或强烈效应。在前一种情况下或当初始态几乎均匀时，我们表明即使是产物态也会变成宏观量子态。