Local photons

Can a localised quantum system see soft photons?

We ask whether soft photons, defined by asymptotic charges, can have consequences for the outcome of localised quantum processes. We consider a spatially localised two-state system, at rest in flat spacetime, coupled to a $U(1)$ gauge invariant charged scalar field. We find that the system's de-excitation rate does depend on the soft charges that correspond to the radial component of the electric field dressing at the asymptotic infinity; the excitation rate, by contrast, remains zero, regardless of the soft charges. Some implications are discussed.

单光子源在波导中的局域激发

Localised excitation of a single photon source by a nanowaveguide

目前，集成光子学是量子信息处理（QIP）的关键技术，但实现单光子发射器的高效集成的量子网络全光总线仍然是一个挑战。光子晶体和空腔是很好的候选者，但没有解决如何有效地解决纳米级发射器。利用纳米线的半导体波导，我们实现了一种混合纳米器件，它可以局部激发单光子源（SPS）。纳米线充当无源或有源亚波长波导以激发量子发射器。我们的研究结果表明，局部激发的SPS是可能的，并与自由空间激发。我们的原理实验证明了绝对寻址效率ηa = 10-4，仅比使用自由空间光学器件的效率低50%。这一重要步骤表明，在半导体纳米线制成的半导体波导中，可以实现足够的引导光来激发单个光子源。我们完成了一个混合系统，提供了巨大的潜力，电驱动的SPS和有效的单光子收集和检测，开辟了最佳的吸收/发射的纳米级发射器的方式。我们还讨论了如何提高寻址效率的偶极纳米级发射器与我们的系统。

描述同时连续测量位置与动量的随机 Schrödinger 方程的局域化解

Localised solution of stochastic Schrödinger equation describing simultaneous continuous measurement of position and momentum

本文提出描述同时连续测量位置与动量的随机 Schrödinger 方程，求解得到满足不确定性原理的局域化状态，表现为中心在相空间随机运动的固定 Gaussian 波包，并证明其局域稳定性。

新型完全平坦拓扑能带——受局部图拓扑保护的紧致局域态

New class of exactly flat topological bands - compact localised states protected by local graph topology

研究在任意图面上构造精确平坦能带哈密顿量的方法，利用阿蒂亚 - 辛格指标定理离散图推广证明简并性受局部拓扑保护，产生紧致局域态，探讨其在量子网络、机器学习及拓扑量子计算等方面的意义。

非惯性系中相对论量子场的定域投影测量

Localised projective measurement of a relativistic quantum field in non-inertial frames

我们提出了一个方案来研究运动对有限尺寸探测器测量量子场的影响。我们介绍了一个模型的投影检测的局部领域模式在任意参考系。我们将其应用于利用一对反加速探测器提取真空纠缠和估计单个加速探测器的Unruh温度。所介绍的方法使我们能够直接与所观察到的效果与检测器的瞬时固有加速度。

Quantum light-matter interaction and controlled phonon scattering in a photonic Fano cavity

The Fano effect arises from the interference between a continuum of propagating modes and a localised resonance. By using this resonance as one of the mirrors in an optical cavity, a localised mode with a highly asymmetric line shape is obtained. Placing a single quantum emitter inside the cavity leads to a new regime of cavity quantum electrodynamics, where the light-matter interaction dynamics is fundamentally different from that observed in a conventional cavity with Lorenztian lineshape. Furthermore, when the vibrational dynamics of the emitter is taken into account, an intricate phonon-ph…