Angular momentum and the geometrical gauge of localized photon staes

Localized dynamics following a quantum quench in a non-integrable system: An example on the sawtooth ladder

Motivated by the recent discovery of ergodicity breaking in geometrically frustrated systems, we study the quench dynamics of interacting hardcore bosons on a sawtooth ladder. We identify a set of initial states for which this system exhibits characteristic signatures of localization like initial state memory retention and slow growth of entanglement entropy for a wide parameter regime. Remarkably, this localization persists even when the many-body spectrum is thermalizing. We argue that the localized dynamics originates from an interaction induced quantum interference. Our results show that t…

几何分形中非遍历多分形量子态的涌现

Emergence of non-ergodic multifractal quantum states in geometrical fractals

本文提出通过迭代在晶格中引入缺陷、构造分形几何，在无无序条件下实现非遍历多分形态，并以 Sierpiński gasket 验证其涌现及实验意义。

基于干涉局域态的双光子极限全光开关

All-optical switching at the two-photon limit with interference-localized states

本研究提出基于晶格干涉局域态及其相互作用退局域化的逐光子全光开关，具备开/关两种工作模式，经理论建模验证，可在现有光子材料下实现任意开关对比度与皮秒级单光子开关速度。

Spontaneous Parametric Down-Conversion in asymmetric couplers: photon purity enhancement and intrinsic spectral filtering

We analyze the process of photon-pair generation via spontaneous parametric down-conversion in a quadratic nonlinear asymmetric waveguide coupler. The two waveguides have different geometry, such that light coupling only occurs within a narrow bandwidth of one of the generated (signal) photon modes, while the other (idler) photon together with the pump stay localized in one (driven) arm of the coupler. We demonstrate that such a setup represents a powerful and flexible tool for engineering spectral properties of generated photon pairs. Mode hybridization and dispersion of coupling can be utili…

Weakly interacting Bose gas in a random environment

Zero temperature properties of a dilute weakly interacting $d$-dimensional Bose gas in a random potential are studied. We calculate geometrical and energetic characteristics of the localized state of a gas confined in a large box or in a harmonic trap. Different regimes of the localized state are found depending on the ratio of two characteristic length scales of the disorder, the Larkin length and the disorder correlation length. Repulsing bosons confined in a large box with average density $n$ well below a critical value $n_c$ are trapped in deep potential wells of extension much smaller tha…