



01706nas a2200193   4500008004100000245008500041210006900126260001400195490000600209520111700215100001901332700001901351700001801370700001601388700002401404700002201428700002501450856003701475       2021                        eng d00aFrustration-induced anomalous transport and strong photon decay in waveguide QED0 aFrustrationinduced anomalous transport and strong photon decay i  c9/16/20210 v33 a<p>We study the propagation of photons in a one-dimensional environment consisting of two non-interacting species of photons frustratingly coupled to a single spin-1/2. The ultrastrong frustrated coupling leads to an extreme mixing of the light and matter degrees of freedom, resulting in the disintegration of the spin and a breakdown of the &quot;dressed-spin&quot;, or polaron, description. Using a combination of numerical and analytical methods, we show that the elastic response becomes increasingly weak at the effective spin frequency, showing instead an increasingly strong and broadband response at higher energies. We also show that the photons can decay into multiple photons of smaller energies. The total probability of these inelastic processes can be as large as the total elastic scattering rate, or half of the total scattering rate, which is as large as it can be. The frustrated spin induces strong anisotropic photon-photon interactions that are dominated by inter-species interactions. Our results are relevant to state-of-the-art circuit and cavity quantum electrodynamics experiments.</p>1 aBelyansky, Ron1 aWhitsitt, Seth1 aLundgren, Rex1 aWang, Yidan1 aVrajitoarea, Andrei1 aHouck, Andrew, A.1 aGorshkov, Alexey, V.  uhttps://arxiv.org/abs/2007.03690