Decoherence-free interaction between giant atoms
In quantum-optics experiments with both natural and artificial atoms, the atoms are usually small enough that they can be approximated as pointlike compared to the wavelength of the electromagnetic radiation with which they interact. However, superconducting qubits coupled to a meandering transmission line, or to surface acoustic waves, can realize “giant artificial atoms” that couple to a bosonic field at several points which are wavelengths apart. We have previously done theoretical studies of a single giant atom, showing among other things how the relaxation rate in such a system becomes frequency-dependent due to interference between the multiple connection points. In this work, we studied setups (shown in the figure) with multiple giant atoms in a one-dimensional (1D) waveguide. We showed that the giant atoms can be protected from decohering through the waveguide, but still have exchange interactions mediated by the waveguide. Unlike in decoherence-free subspaces, here the entire multiatom Hilbert space is protected from decoherence. This is not possible with “small” atoms. We further showed how this decoherence-free interaction can be designed in setups with multiple atoms to implement, e.g., a 1D chain of atoms with nearest-neighbor couplings or a collection of atoms with all-to-all connectivity. This may have important applications in quantum simulation and quantum computing.
Decoherence-free interaction between giant atoms in waveguide quantum electrodynamics
Anton Frisk Kockum, Göran Johansson, and Franco Nori
arXiv:1711.08863
