Abstract
It has long been recognized that emission of radiation from atoms is not an intrinsic property of individual atoms themselves, but it is largely affected by the characteristics of the photonic environment and by the collective interaction among the atoms. A general belief is that preventing full decay and/or decoherence requires the existence of dark states, i.e., dressed light-atom states that do not decay despite the dissipative environment. Here, we show that, contrary to such a common wisdom, decoherence suppression can be intermittently achieved on a limited time scale, without the need for any dark state, when the atom is coupled to a chiral ring environment, leading to a highly non-exponential staircase decay. This effect, that we refer to as intermittent decoherence blockade, arises from periodic destructive interference between light emitted in the present and light emitted in the past, i.e., from delayed coherent quantum feedback.
Highlights
It has long been recognized that emission of radiation from atoms is not an intrinsic property of individual atoms themselves, but it is largely affected by the characteristics of the photonic environment and by the collective interaction among the atoms
Since the atom cannot be considered point-like anymore, spontaneous emission ceases to be exponential and the decay dynamics is described by a differential-delayed equation[25,27,30,33], displaying strictly non-Markovian effects arising from delayed coherent quantum feedback[34,35,36]
In this work we show rather surprisingly that, harnessing the idea of delayed coherent quantum feedback in a reservoir with effective discrete and continuous mode structure, a point-like atom emitting in a chiral ring photonic waveguide, sustaining slow and fast counter-propagating photonic modes, undergoes intermittent decoherence suppression on a fast time scale, displaying an exotic staircase decay dynamics
Summary
It has long been recognized that emission of radiation from atoms is not an intrinsic property of individual atoms themselves, but it is largely affected by the characteristics of the photonic environment and by the collective interaction among the atoms. One among the most striking phenomena achieved through complex environment engineering is the possibility to inhibit spontaneous emission and dechoerence under certain geometric conditions, i.e. the stabilization of quantum superposition states in the presence of dissipation or other forms of decay channels or dephasing This goal is of major relevance in different contexts ranging from quantum computation, where limiting effects of decoherence[47] and decoherence-free-space have been broadly studied[48,49], to quantum biology[50,51,52] and quantum chemistry[53,54], where pure dephasing and non-radiative channels are the main sources that destroy electronic coherence in molecular dynamics. A fully open question is whether spontaneous emission and decoherence
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