Quantum waveguides

Pavel Exner, Hynek Kovařík

Alexey A. Melnikov, A. P. Alodjants, Leonid Evgenevich Fedichkin

Abstract Modern integrated photonic quantum technologies are based on optical waveguides. The propagation of light in optical waveguides allows one to implement quantum computation and bosonic quantum simulation. Nevertheless, to further develop photonic quantum devices, one needs a precise mathematical description of quantum dynamics in waveguides. In this paper, we consider a double-layer array of optical waveguides and find exact analytical expressions for the Hamiltonian of the system and its parameters. The results are obtained both in the ideal waveguide approximation and in the case of photon loss in the waveguides.

Nzar Rauf Abdullah, Chi‐Shung Tang, Andrei R. Manolescu +1 more

We study a cavity-photon-switched coherent electron transport in a symmetric double quantum waveguide. The waveguide system is weakly connected to two electron reservoirs, but strongly coupled to a single quantized photon cavity mode. A coupling window is placed between the waveguides to allow electron interference or inter-waveguide transport. The transient electron transport in the system is investigated using a quantum master equation. We present a cavity-photon tunable semiconductor quantum waveguide implementation of an inverter quantum gate, in which the output of the waveguide system may be selected via the selection of an appropriate photon number or “photon frequency” of the cavity. In addition, the importance of the photon polarization in the cavity, that is, either parallel or perpendicular to the direction of electron propagation in the waveguide system is demonstrated.

Jingbo Wang

X. N. Feng, Huaiyuan Liu, L. F. Wei

The waveguide Fabry-Perot interferometer (FPI) (see, e.g., in Phys. Rev. Lett.113, 243601 (2015)10.1103/PhysRevLett.115.243601 and Nature569, 692 (2019)10.1038/s41586-019-1196-1), instead of the free space's one, have been demonstrated for the sensitive quantum parameter estimations. Here, we propose a waveguide Mach-Zehnder interferometer (MZI) to further enhance the sensitivity of the relevant parameter estimations. The configuration is formed by two one-dimensional waveguides coupled sequentially to two atomic mirrors, which are served as the beam splitters of the waveguide photons to control the probabilities of the photons being transferred from one waveguide to another. Due to the quantum interference of the waveguide photons, the acquired phase of the photons when they pass through a phase shifter can be sensitively estimated by measuring either the transmitted or reflected probabilities of the transporting photons. Interestingly, we show that, with the proposed waveguide MZI the sensitivity of the quantum parameter estimation could be further optimized, compared with the waveguide FPI, in the same condition. The feasibility of the proposal, with the current atom-waveguide integrated technique, is also discussed.