Waveguide QED with a giant transmon

Nikos Fayard, Adrien Bouscal, Jérémy Berroir +9 more

Jonas Larson, Th. K. Mavrogordatos

Xian-Li Yin, Yu-Hong Liu, Jin-Feng Huang +1 more

We study the coherent single-photon scattering in a one-dimensional waveguide coupled to a giant artificial molecule consisting of two coupled giant atoms. Since each giant atom couples to the waveguide via two coupling points, the couplings of the molecule with the waveguide have three different coupling configurations: the separated-, braided-, and nested-coupling cases. We obtain the exact expressions of the single-photon transmission and reflection amplitudes with the real-space approach. It is found that the behavior of the scattering spectra depends on the phase shift between two neighboring coupling points, the coupling configuration, and the coupling between the two giant atoms. Concretely, we study the photon scattering in both the Markovian and non-Markovian regimes, in which the photon propagating time between two neighboring coupling points is neglected and considered, respectively. Under the Markovian limit, the asymmetric Fano line shapes in different coupling configurations of the giant-molecule waveguide-QED system can be obtained by choosing proper phase shift, and the transmission window can be adjusted by the coupling strength between the two giant atoms in these three coupling configurations. In particular, multiple reflection peaks and dips in these configurations are revived in the non-Markovian regime. This paper will pave the way for the study of controllable single-photon devices based on the giant-molecule waveguide-QED systems.

Jie Liu, Zhiqiang Liu, Yue Cai +3 more

Abstract The entanglement transfer is investigated between giant atoms in waveguide‐QED systems. The two giant atom pairs, and , are independently coupled to their respective waveguides. Initially, entanglement are stored in atom pair . There three giant atom configurations are considered: separated, braided, and nested. For comparison, the small atom configuration is also studied here. The focus is on entanglement transfer from atom pair to atom pair and atom pair in these four coupling configurations. It is shown that the transfer of entanglement in each configuration strongly depends on phase shift. In particular, the braided configuration demonstrates superior performance in entanglement transfer. For the entanglement transfer from atom pair to atom pair , complete entanglement transfer is presented in braided configuration, a behavior not found in small atom or other giant atom configurations. For the entanglement transfer from atom pair to atom pair , although the maximum entanglement transferred to atom pair in the braided configuration is half of that one to atom pair , it is still higher than that in the small atom, separated, and nested configurations. This study lays the foundation for entanglement transfer between giant atoms in waveguide‐QED platforms.

Pavel Exner, Hynek Kovařík

Pavel Exner, Petr Šeba, Pavel Šťovíček