Mechanism of decoherence-free coupling between giant atoms
Angelo C. M. Carollo, Dario Cilluffo, Francesco Ciccarello · Physical Review Research · 2020
Giant atoms are a new paradigm of quantum optics going beyond the usual local coupling.Building on this, a new type of decoherence-free (DF) many-body Hamiltonians was shown in a broadband waveguide.Here these are incorporated in a general framework (not relying on master equations) and contrasted to dispersive DF Hamiltonians with normal atoms: the two schemes are shown to correspond to qualitatively different ways to match the same general condition for suppressing decoherence.Next, we map the giant atoms dynamics into a cascaded collision model (CM), providing an intuitive interpretation of the connection between nontrivial DF Hamiltonians and coupling points topology.The braided configuration is shown to implement a scheme where a shuttling system subject to periodic phase kicks mediates a DF coupling between the atoms.From the viewpoint of CMs theory, this shows a collision model where ancillas effectively implement a dissipationless, maximally entangling two-qubit gate on the system.