Photonic simulation of giant atom decay

Abstract

Spontaneous emission of an excited atom in a featureless continuum of electromagnetic modes is a fundamental process in quantum electrodynamics associated with an exponential decay of the quantum emitter to its ground state accompanied by an irreversible emission of a photon. However, such a simple scenario is deeply modified when considering a ′ giant ′ atom, i.e an atom whose dimension is larger than the wavelength of the emitted photon. In such an unconventional regime, non-Markovian effects and strong deviations from an exponential decay are observed owing to interference effects arising from non-local light-atom coupling. Here we suggest a photonic simulation of non-Markovian giant atom decay, based on light escape dynamics in an optical waveguide non-locally-coupled to a waveguide lattice. Major effects such as non-exponential decay, enhancement or slowing down of the decay, and formation of atom-field dark states can be emulated in this system.

Intermittent decoherence blockade in a chiral ring environment

“…( 6 ) and ( 7 ), the amplitude and its derivative are continuous functions of time t , as it should be on physical grounds, However, as discussed in the next section, for a large number N of sites in the ring the numerically-computed evolution of displays rather sharp changes at time instants corresponding to periodic feedback from the ring. Such a scenario, which is similar to the dynamical behavior observed for a point-like two-level atom radiating in front of a mirror 37 , 39 , 40 , can be captured by approximating the exact integro-differential equations ( 6 , 7 ) with a differential-delayed equation 32 , 40 . To this aim, let us note that in the large N limit the sum over k on the right hand side of Eq.…”

Giant atoms with time-dependent couplings

“…This can be seen from the inset of Fig. 5, where the atomic decay is almost suppressed if the model enters the Markovian regime with small enough τ (see, e.g., the green line with τ = d/v g = N/2J = 0.025/g 0 [49,57]). More-over, the present scheme is different from that of the small-atom case [53], where the atom is assumed to be off resonant with the lattice and its decoherence is partially suppressed due to the formation of an atom-photon bound state.…”

“…In this case, the giant atom is effectively decoupled from the waveguide and becomes "decoherence free" [9,11]. On the other hand, the atom can also exhibit superradiance behavior if the two coupling channels interfere constructively (in this context, "superradiance" refers to stronger decay due to the giant-atom structure [49]).…”

“…( 16) basically describes a giant atom weakly coupled to a bath where photon escape from the atom to the lattice can be observed; Otherwise, if the atom is tuned off-resonance to the lattice band, the photon escape is prohibited and atom-photon bound states can be formed [54][55][56]. In the resonant case of ω 0 = ω a (i.e., the frequency of the atom lies at the middle of the energy band of the lattice), the phase accumulation between the two atom-lattice coupling points is given by φ = N π/2 [49,57]. In this case, the dynamic evolution of the atomic population |c e (t)| 2 can be determined by solving the coupled-mode equations…”

“…We first consider the case of N = 4 where the atom exhibits enhanced decay compared with the small-atom correspondence [27,49]. Figure 4 the dynamic evolutions of the atomic population in this case with different values of quench-off duration t ′′ and depicts also the evolution without coupling quench for comparison.…”