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Journal of the Optical Society of America B

Photon transport mediated by a trimer QED system with PT-symmetry

Haozhen Li, Ran Zeng, Xuefang Zhou, Miao Hu, Xiuwen Xia, Mu-Tian Cheng, Jingping Xu, Yaping Yang

Published Feb 22, 2022• 0 citations
Publisher

Abstract

The photon transport in a pair of parallel waveguides mediated by a parity-time- (PT-) symmetric trimer QED system is investigated. We demonstrate that the transport behaviors of the incident photons transferring between different waveguides can be actively controlled by the PT symmetry. The efficiency of such photon transport can be tuned to be much larger than 100% when the optical gain is introduced, and the transfer intensity is robust against the weak coupling among the atom, the cavity modes, their corresponding coupling mismatch, as well as the atomic dissipation. Furthermore, we demonstrate that when the system is excited by two input fields, the relative phase of the two input signals can serve as a sensitive control parameter for manipulating the photon transport, and controllable directional amplification of the incident signal photons with a fixed frequency can be realized by modulating the relative phase. The obtained results can be useful for designing phase-dependent active nonreciprocal devices, i.e., a phase-sensitive directional amplifier.

DOI
10.1364/josab.445390

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The photon transport in a pair of parallel waveguides mediated by a parity-time- (PT-) symmetric trimer QED system is investigated. We demonstrate that the transport behaviors of the incident photons transferring between different waveguides can be actively controlled by the PT symmetry. The efficiency of such photon transport can be tuned to be much larger than 100% when the optical gain is introduced, and the transfer intensity is robust against the weak coupling among the atom, the cavity modes, their corresponding coupling mismatch, as well as the atomic dissipation. Furthermore, we demonstrate that when the system is excited by two input fields, the relative phase of the two input signals can serve as a sensitive control parameter for manipulating the photon transport, and controllable directional amplification of the incident signal photons with a fixed frequency can be realized by modulating the relative phase. The obtained results can be useful for designing phase-dependent active nonreciprocal devices, i.e., a phase-sensitive directional amplifier.
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Enhanced nonlinear characteristics with the assistance of a PT\mathscr{PT}PT-symmetric trimer system
We study the parity-time (PT) symmetry characteristics and the applications to nonlinear optics in an optical trimer system consisting of two indirectly coupled standing-mode micro-cavities and a two-level quantum emitter (QE) placed at the intersection of two cavities. We find this trimer system can exhibit analogical phenomena as those in typical [Formula: see text]-symmetric dimer systems composed of a passive cavity directly coupled to an active cavity. This system, whose [Formula: see text] symmetry is demonstrated by our analytic results, can be transformed between the [Formula: see text]-symmetric phase and the [Formula: see text]-broken phase by adjusting relevant system parameters. Then, with this system, we observe both the linear and nonlinear parts of the transmission field become remarkably enhanced and can further reach peak values around the [Formula: see text] breaking point. In addition, we show the negative correlation between the gain degree of the linear (nonlinear) transmission part and decay rate of the QE. This trimer proposal is feasible for experiments and may provide a promising platform for [Formula: see text]-symmetric optics of low-light levels. Moreover, novel phenomena arising from the QE-cavity-coupling induced nonlinearity gain could be explored to fabricate photonic devices and controllable nonlinear optical media for quantum information process and communication of photons.
The dynamic control of single-photon scattering in a pair of one-dimensional waveguides mediated by a time-modulated atom–cavity system is investigated. Two cases, where the waveguides are coupled symmetrically or asymmetrically to the atom–cavity system, are discussed in detail. The results show that such time-modulated atom–cavity configuration can behave as a dynamical tunable directional single-photon router. The photons with different frequencies can dynamically be routed from the incident waveguide into any ports of the other with a 100% probability via adjusting the modulated amplitude or phases of the time-modulated atom–cavity coupling strengths, associate with the help of the asymmetrical waveguide–cavity couplings. Furthermore, the influence of dissipation on the routing capability is investigated. It is shown that the present single-photon router is robust against the dissipative process of the system, especially the atomic dissipation. These results are expected to be applicable in quantum information processing and design quantum devices with dynamical modulation.
The dynamics of a coherent wave packet traveling through a two-mode waveguide, coupled to a cavity embedded with a two-state quantum system, is analyzed. The guided coherent wave transmission and reflection coefficients, as well as the atom and cavity excitation amplitudes, are solved exactly via a real-space approach. We show that a two-point waveguide coupled to a Rydberg-atom hybrid system can tailor the waveform of the incident coherent pulse wave into other forms by controlling the coupling strength tuning between the waveguide, the cavity, and the atom. Tailoring involves modifying properties such as amplitude, phase, or spectral content based on the quantum system interaction. This phenomenon is different from the situation of the plane wave input, where the transmitted and reflected waves are the plane waves and the same to the incident one. Consequently, we provide an effective method that can be used to tailor pulse-wave propagation to enhance efficient quantum sensitivity in the field of ultrafast photonics devices.
The dynamical control of single-photon scattering in a one-dimensional waveguide coupled to a Floquet atom-cavity system with time-modulated coupling constants is investigated. The analytical expressions for determining the scattering properties are obtained by using an effective Floquet Hamiltonian in real space. The photon transport is extremely sensitive to the time-modulated atom-cavity coupling strengths. Two cases, i.e., the effective Floquet Hamiltonian either includes or excludes a static coupling term, are discussed in detail. The results show that, with such Floquet atom-cavity configuration, an active photonic switch with nearly ideal switching contrast could be implemented. The transmission of the waveguide photons with different frequencies can dynamically be switched on or off via adjusting the modulated amplitude or relative modulated phase no matter whether the static coupling between the atom and the two cavity modes is considered or not. The application of the dynamic modulated atom-cavity coupling strengths instead of a purely static one makes our photonic switch more tunable. These results are expected to be applicable in quantum information processing and in active quantum device design involving dynamical modulation.
Abstract. We show both theoretically and experimentally that a pair of inductively coupled active LRC circuits (dimer), one with amplification and another with an equivalent amount of attenuation, display all the features which characterize a wide class of non-Hermitian systems which commute with the joint parity-time PT operator: typical normal modes, temporal evolution, and scattering processes. Utilizing a Liouvilian formulation, we can define an underlying PT-symmetric Hamiltonian, which provides important insight for understanding the behavior of the system. When the PT-dimer is coupled to transmission lines, the resulting scattering signal reveals novel features which reflect the PT-symmetry of the scattering target. Specifically we show that the device can show two different behaviors simultaneously, an amplifier or an absorber, depending on the direction and phase relation of the interrogating waves. Having an exact theory, and due to its relative experimental simplicity, PT-symmetric electronics offers new insights into the properties of PT-symmetric systems which are at the forefront of the research in mathematical physics and related fields. PACS numbers: 11.30.Er, 05.60.-k, 45.05.+x 1.