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Optics Express

Giant atom-mediated single photon routing between two waveguides

Chen Wang, Xiao-San Ma, Mu-Tian Cheng

Published Nov 3, 2021• 38 citations
Publisher

Abstract

In this work, the single photon scattering due to a giant atom coupled with a pair of waveguides is investigated theoretically. Using the real-space Hamiltonian, four scattering amplitudes are obtained, and the single photon routing properties are studied. Calculations reveal that the single photon routing properties are strongly dependent on the size of the giant atom. The possible physical mechanism is also discussed. To improve routing efficiency, the configuration where one waveguide is terminated is further studied. The calculated results indicate that an incident photon can be transferred to the other waveguide with unit efficiency by choosing the appropriate configuration for a fixed size of the giant atom. Our results may be used in quantum information processing and design quantum devices at single-photon level.

DOI
10.1364/oe.444096

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In this work, the single photon scattering due to a giant atom coupled with a pair of waveguides is investigated theoretically. Using the real-space Hamiltonian, four scattering amplitudes are obtained, and the single photon routing properties are studied. Calculations reveal that the single photon routing properties are strongly dependent on the size of the giant atom. The possible physical mechanism is also discussed. To improve routing efficiency, the configuration where one waveguide is terminated is further studied. The calculated results indicate that an incident photon can be transferred to the other waveguide with unit efficiency by choosing the appropriate configuration for a fixed size of the giant atom. Our results may be used in quantum information processing and design quantum devices at single-photon level.
We investigate the single-photon quantum routing composed of two infinite waveguides coupled to two giant two-level atoms. The exact expressions of the single-photon transmission and reflection amplitudes are derived with the real-space approach. It is found that the single photon scattering behavior is strongly dependent on the phase difference between the two adjacent atom-waveguide coupling points, the frequency detuning, the coupling strength between the two giant atoms, and the interaction strengths between the giant atoms and the waveguides. Our studies show that an ideal single photon router with unit efficiency can be realised by designing the size of the giant atom, and the frequency detuning or adjusting the interaction strengths between the atoms and the waveguides. The results suggest the potential to effectively control the single-photon quantum routing based on the giant-atom setup.
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.
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.
We propose a frequency-controllable single-photon router in a giant atom waveguide QED system, in which two linear waveguides are mediately by two coupled giant atoms. Since each giant atom has two coupling points, a pair of giant atoms can be arranged as three different topologies: separated, braided, and nested. The exact analytical expressions of the four scattering amplitudes for the three different topologies are obtained with the real-space approach. We find that the deterministic routing scheme is strongly relevant to the energy and the decay rates of the collective states of the two coupled giant atoms. In particular, only if the two scattering states degenerate in energy and decay rates, the frequency-tunable router with 100% efficiency can be achieved in the three different topologies. Moreover, our numerical results show that the single-photon routing scheme in the current model is more tunable and robust than that in the normal atom waveguide QED system. The physics behind the complete routing scheme is also illuminated. Our results pave the way for the study of controllable single-photon router devices involving giant atoms.
Abstract The phase-controlled single-photon transport properties of a giant atom coupled to a one-dimensional waveguide are investigated. The coupling between the giant atom and the waveguide is modeled as a multi-point interaction. The coupling strengths between the giant atom and the waveguide are represented as complex numbers with associated phases. Analytical expressions for the scattering amplitudes are obtained using the real-space Hamiltonian method. The results show that the characteristics of the scattering spectra, including the positions of peaks (or dips) and the full width at half maximum, can be tuned by adjusting the phase difference between the coupling strengths. Further calculations reveal that the scattering spectra can be either super-broadened or sub-broadened. The conditions for achieving perfect nonreciprocal single-photon transport in the Markovian regime are also discussed. Moreover, we demonstrate the control of single-photon transport through phase differences in the non-Markovian regime. Our results may find applications in the design of quantum devices operating at the single-photon level, based on waveguide quantum electrodynamics.
Abstract We investigate a π-shaped single-photon router composed of an infinite waveguide and two semi-infinite waveguides coupled through double two-level giant atoms, where each giant atom is further coupled to a single-mode cavity. Using the real-space approach, analytical expressions of the single-photon scattering amplitudes are derived. The numerical results show that optimal routing with unit efficiency can be achieved by precisely adjusting frequency detunings between the incident photon and the atomic as well as cavity resonances, the accumulated phase, local coupling phases and coupling strengths between atoms, waveguides and cavities. Additionally, chiral single-photon scattering is observed, demonstrating a strong direction-dependence in the scattering properties, with perfect chiral scattering achieved under specific phase-matching conditions. We believe that our research has considerable potential applications for designing advanced optical quantum devices and implementing efficient single-photon quantum routing based on giant atom architectures.