Controlling photons by phonons via giant atom in a waveguide QED setup

Nonreciprocal excitation and entanglement dynamics of two giant atoms mediated by a waveguide

We study the nonreciprocal excitation and entanglement dynamics of two giant atoms (GAs) coupling to a one-dimensional waveguide. With different positions of coupling points, three configurations of two separate GAs, two braided GAs, and two nested GAs are analyzed, respectively. The coupling strengths between different coupling points are considered as complex numbers with phases. For each coupling configuration, the nonreciprocal excitation dynamics and entanglement properties, which results from the phase differences of coupling strength and the phase induced by photon propagation between the two coupling points, are studied both in Markovian and non-Markovian regimes. The analytical solutions for nonreciprocal entanglement degree are given in the Markovian regime. It shows that the steady entanglement can be reached and strongly depends on the phases. Different from the case of the Markovian regime, the entanglement degree shows oscillating behavior in the non-Markovian regime. This work may find applications in the generation and controlling of entanglement in quantum networks based on waveguide quantum electrodynamics.

Temperature-related single-photon transport in a waveguide QED

We propose a scheme to realize a novel, to the best of our knowledge, scenario that the single-photon transport in a one-dimensional waveguide can be affected by the temperature. The scheme is composed by a waveguide-atom interacting structure linked to a thermal bath. The single-photon reflection (or transmission) coefficient can be controlled by adjusting the temperature of the thermal bath. This provides a thermal control of the single-photon transport. Moreover, the scheme provides an approach for implementing the optical thermometer, in which the temperature of the thermal bath is estimated by measuring the photonic transport. The thermometer can accurately measure the temperature in the low-temperature region.