3 research outputs found
Visualizing the emission of a single photon with frequency and time resolved spectroscopy
At the dawn of Quantum Physics, Wigner and Weisskopf obtained a full
analytical description (a \textit{photon portrait}) of the emission of a single
photon by a two-level system, using the basis of frequency modes (Weisskopf and
Wigner, "Zeitschrift f\"ur Physik", 63, 1930). A direct experimental
reconstruction of this portrait demands an accurate measurement of a time
resolved fluorescence spectrum, with high sensitivity to the off-resonant
frequencies and ultrafast dynamics describing the photon creation. In this work
we demonstrate such an experimental technique in a superconducting waveguide
Quantum Electrodynamics (wQED) platform, using single transmon qubit and two
coupled transmon qubits as quantum emitters. In both scenarios, the photon
portraits agree quantitatively with the predictions of the input-output theory
and qualitatively with Wigner-Weisskopf theory. We believe that our technique
allows not only for interesting visualization of fundamental principles, but
may serve as a tool, e.g. to realize multi-dimensional spectroscopy in
waveguide Quantum Electrodynamics.Comment: 18 pages, 10 figures including appendice
Terahertz heterodye detection based on ion-irradiated high-Tc Josephson junctions and arrays
International audienc
Collective bosonic effects in an array of transmon devices
Abstract
Multiple emitters coherently interacting with an electromagnetic mode give rise to collective effects such as correlated decay and coherent exchange interaction, depending on the separation of the emitters. By diagonalizing the effective non-Hermitian many-body Hamiltonian we reveal the complex-valued eigenvalue spectrum encoding the decay and interaction characteristics. We show that there are significant differences in the emerging collective effects for an array of interacting anharmonic oscillators compared to those of two-level systems and harmonic oscillators. The bosonic decay rate of the most superradiant state increases linearly as a function of the filling factor and exceeds that of two-level systems in magnitude. Furthermore, with bosonic systems, dark states are formed at each filling factor. These are in strong contrast with two-level systems, where the maximal superradiance is observed at half-filling and with larger filling factors superradiance diminishes and no dark states are formed. As an experimentally relevant setup of bosonic waveguide QED, we focus on arrays of transmon devices embedded inside a rectangular waveguide. Specifically, we study the setup of two transmon pairs realized experimentally in Zanner et al. [Nat. Phys. 18, 538 (2022)] and show that it is necessary to consider transmons as bosonic multilevel emitters to accurately recover correct collective effects for the higher excitation manifolds