Quantum Optics with Giant Atoms in 2D Structured Environments

Abstract

One of the major hurdles in the ongoing efforts to construct a working large-scale quantum computer is achieving rapid interactions between qubits without risking a loss of energy (and thus information) to their surroundings. This loss of energy is known as decoherence. In recent years, one possible solution to this problem that has shown promise is the use of so-called giant atoms. In certain configurations, these systems have been shown to exhibit decoherence-free interaction (DFI) when coupled to one-dimensional environments, such as transmission lines or photonic crystal waveguides. For DFI to be possible, the atoms involved must be perfectly subradiant – that is, they must not spontaneously decay into their environments. In this study, we used numerical simulations combined with the methods of resolvent formalism to examine under what conditions giant atoms exhibit perfect subradiance and DFI when coupled to two-dimensional (2D) environments. More specifically, structured 2D environments – i.e. resonator lattices – were considered. In such environments, there are finite energy bands and band gaps, which causes effects that are not predicted by the so-called Born-Markov approximation, e.g. time delay. Multiple generalisations of previously known setups exhibiting perfect subradiance were found. Furthermore, a number of different configurations exhibiting DFI were discovered, including grid-like ones that in principle could be extended indefinitely.