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Physical Review A

Controllable single-photon wave-packet scattering in a two-dimensional resonator array by a giant atom

Weijun Cheng, Zhihai Wang, Yu-xi Liu

Published Nov 17, 2025• 3 citations
Publisher

Abstract

Nonlocal interactions between photonic resonator array and giant atoms have attracted extensive attentions. Optimization and control of quantum states via giant atoms have been shown. We here study the dynamical scattering of a single-photon wave packet by a giant atom coupled to a two-dimensional photonic resonator array via multiple spatial points. Using several iterations of time evolutions, we can prepare an expected wave packet with a stable size and use it as the incident state for the scattering process. We show that spatially symmetric or asymmetric target scattering states of single-photon wave packet can be generated by adjusting the coupling strengths between the giant atom and different lattice sites of the resonator array. Furthermore, the dynamical scattering of the wave packets enables us to study the atomic excitation and propagating properties of the scattering states. We find that the atomic excitation has negligibly small probability during the scattering process. Our study may provide a new way to generate an expected photon state via photon scattering by a giant atom in two-dimensional photonic array.

DOI
10.1103/99nn-9wxs

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Nonlocal interactions between photonic resonator array and giant atoms have attracted extensive attentions. Optimization and control of quantum states via giant atoms have been shown. We here study the dynamical scattering of a single-photon wave packet by a giant atom coupled to a two-dimensional photonic resonator array via multiple spatial points. Using several iterations of time evolutions, we can prepare an expected wave packet with a stable size and use it as the incident state for the scattering process. We show that spatially symmetric or asymmetric target scattering states of single-photon wave packet can be generated by adjusting the coupling strengths between the giant atom and different lattice sites of the resonator array. Furthermore, the dynamical scattering of the wave packets enables us to study the atomic excitation and propagating properties of the scattering states. We find that the atomic excitation has negligibly small probability during the scattering process. Our study may provide a new way to generate an expected photon state via photon scattering by a giant atom in two-dimensional photonic array.
Nonlocal interactions between photonic resonator array and giant atoms have attracted extensive attentions. Optimization and control of quantum states via giant atoms have been shown. We here study the dynamical scattering of a single-photon wave packet by a giant atom coupled to a two-dimensional photonic resonator array via multiple spatial points. Using several iterations of time evolutions, we can prepare an expected wave packet with a stable size and use it as the incident state for the scattering process. We show that spatially symmetric or asymmetric target scattering states of single-photon wave packet can be generated by adjusting the coupling strengths between the giant atom and different lattice sites of the resonator array. Furthermore, the dynamical scattering of the wave packets enables us to study the atomic excitation and propagating properties of the scattering states. We find that the atomic excitation has negligibly small probability during the scattering process. Our study may provide a new way to generate an expected photon state via photon scattering by a giant atom in two-dimensional photonic array.
Abstract We study single photon scattering in a one-dimensional coupled resonator waveguide, which is dressed by a small and a giant artificial atom simultaneously. Here, we have set the small atom to be a neighbor to one leg of the giant atom, and the giant atom couples to the waveguide via two distant sites. When the small and giant atoms are both resonant with the bare resonator in the waveguide, we observe the perfect reflection of the resonant incident photon. On the other hand, when the small atom is detuned from the giant atom, the single photon reflection is characterized by a wide window and Fano line shape. We hope our work will pave the way for the potential application of small and giant atom hybrid systems in the study of photonic control in the low-dimensional waveguide structure.
We theoretically investigate coherent controlling single photon transport in one-dimensional waveguide coupled to a giant atom interacting with a resonator. The giant atom is considered as a Λ-type system. One transition of the atom couples to the waveguide and the other one is driven by the resonator. Single photon scattering amplitudes are calculated for three kinds of coupling schematics, respectively. Both the analytical and numerical results show that single photon scattering properties can be manipulated by adjusting the size of the giant atom, the coupling strengths of the waveguide-resonator and resonator-giant atom. Specifically, the transmission spectra exhibit two Rabi-splitting dips and the locations of the dips are strongly dependent on the size of the giant atom (GA). It also shows that the resonant single photon can be tuned from being transmitted to being reflected by controlling the coupling strength. Our results may find applications in designing quantum devices based on giant atom at single-photon level.
This work investigates single-photon scattering in a one-dimensional coupled-resonator waveguide coupled to a giant atom with a complex on-site energy. Within the generalized projection operator formalism, we derive analytical expressions for the scattering coefficients. We find that a lossy giant atom absorbs the incident wave, whereas a gain giant atom not only amplifies the incident wave but also leads to scattering divergence at certain energies, corresponding to spectral singularities. We explore the critical scattering dynamics associated with these singularities, and attribute the persistent wave emission to the existence of a stationary bound state in the continuum. Due to the presence of this bound state, the conventional time-independent scattering theory proves inadequate for such a non-Hermitian system. Furthermore, we show that the system with gain always features at least one time-growing bound state, which dominates the long-time dynamics, and we verify our time-dependent theoretical predictions via numerical simulations of Gaussian wave packet scattering.
In this paper, we propose a single-photon routing scheme using a hybrid system, where a two-level giant atom is coupled to a pair of one-dimensional coupled-resonator waveguides. Using the discrete-coordinate scattering approach, exact expressions of the four scattering coefficients are obtained, and the single-photon routing properties are studied. We find that the single-photon routing properties are closely related to the size of the giant atom, the coupling strength between the giant atom and waveguides, and the phase difference between two coupled channels of the atom-upper (lower) waveguide. Without considering the effect of phases of the atom-waveguide coupling coefficients, the probability for a single-photon routing from one waveguide to the other does not exceed 5050%50. However, by properly selecting coupling points between the giant atom and two waveguides, and the phase difference between two atom-upper (lower) waveguide coupling coefficients, a single photon can be transferred from the input port to an arbitrarily selected output port deterministically, i.e., with 100100%100 probability. It is also found that chiral and nonreciprocal single-photon scattering can be realized in our model by properly adjusting the phase difference between two atom-upper (lower) waveguide coupled channels. Our paper offers a promising route towards achieving tunable single-photon routing and constructing optical scalable quantum networks.
Abstract The giant atom, which means the nonlocal atom-waveguide coupling, gives lots of newfangled physics. In this paper, we study the single- and two-photon scattering in the waveguide quantum electrodynamics on a two-level giant atom. For single-photon scattering, we find that the transmission rate is dependent on the atomic size. For the two-photon scattering, using a reasonable wave function hypothesis, we can get the two-photon scattering state, which consists of the symmetric and anti-symmetric plane wave functions. The other eigenstate is the two-photon bound state, which is orthogonal to the two-photon scattering state. We find that the spatial extent of the two-photon bound state is related to the detuning between waveguide and atom, which is distinguished from the character of the general atom. Our study is beneficial to photon control and the fundamental research of the two-photon scattering.