Phase-modulated quantum routing with a giant atom

Alexis R. Legón, Mario Miranda, P. A. Orellana

Ruolin Chai, Guoqing Cai, Qiongtao Xie +2 more

A. Kuzmich, T. Chanelière, Dzmitry Matsukevich

J X Zhou, Z H Zhu, Yi‐Qi Zhang +5 more

Abstract We investigate a T -shaped single-photon router constructed by two waveguides connected via a giant Λ-type three-level atom. Under a real-space approach, the analytical expressions of the single-photon transmission and reflection amplitudes are obtained. It is shown that a high transfer-rate routing between two waveguides can be effectively achieved by modulating the phase difference, the accumulated phase and the atom-waveguide coupling strengths, and its frequencies can be tuned with a classical driving field. Interestingly, chiral scattering and a single-photon targeted router with direction selectivity have been realized by the ideally equivalent atom-waveguide interaction. We believe that our results have potential applications in constructing optical quantum devices and designing the single-photon quantum routing using the giant-atom setup.

Ji Qi, Xiaojun Zhang, Honngwei Yu +1 more

Giant atoms, which couple to a waveguide through multiple spatially separated connection points beyond the dipole approximation, provide a versatile route for quantum information processing based on interference-induced bound states in the continuum (BICs). While multi-giant-atom architectures are being developed toward giant-atom quantum networks, the role of direct coupling between the giant atoms, in particular the associated coupling phase, in atomic dynamics remains insufficiently understood. Here we take a first step toward addressing this issue by studying a two-giant-atom waveguide-QED model. We show that the coupling phase can be used to control both the number of BICs and their profiles for both of photon and atoms. More interestingly, the presence of BICs gives rise to a variety of dynamical behaviors, providing an effective mechanism for tailoring quantum-state evolution in giant-atom waveguide-QED systems. Our results highlight coupling-phase engineering as a useful tool for controlling interference, bound states, and quantum dynamics in nonlocal light--matter interfaces.

Peng-Fei Wang, Lei Huang, Miao-Miao Wei +2 more

We investigate the entanglement dynamics of two giant atoms coupled to a common waveguide. By introducing additional phase modulation at each coupling point, every photon propagation path is jointly controlled by two distinct coupling phases, enabling precise and flexible manipulation of the entanglement evolution. This phase engineering induces destructive interference among different paths, leading to entanglement dynamics in nested giant atoms that become equivalent to those of small atoms, as well as dynamical equivalence between separated and braided configurations. Furthermore, the proposed scheme significantly enhances the robustness of entanglement against variations in the phase shift, offering a practical route to generate stable entanglement and enabling quantum devices with programmable propagation and controllable memory effects.