Quantum Filtering Engineering Of The Radiative Properties Of Driven Quantum Systems

With the continuous development of high-resolution spectroscopic technique,the manip-ulation of radiation field in frequency domain has been penetrated into few-photon and mul-tiphoton levels,and has been widely applied in the fields of quantum information technology,the detections of atomic and molecular transient dynamics,as well as the design of nonclas-sical light source.Among them,the spectral control and application of the radiative proper-ties of the strongly driven quantum emitters have gradually developed into a new branch of spectroscopy——Mollow spectroscopy.The core idea is to scan the output of resonance flu-orescence,such as the famous Mollow triplet,with special spectral properties onto an optical target to probe its internal-state information with high precision.Especially,with the develop-ment of nanotechnology in recent years,as artificial atoms with advantages of wide excitation spectrum and narrow emission spectrum,quantum dots have laid a solid experimental founda-tion for the Mollow spectroscopy.Compared with the Mollow triplet in the laser-dressed two-level systems,can the res-onance fluorescence of three-level systems provide more advantages for the manipulation of photon statistical properties due to its more abundant spectral diversity?In view of this consider-ation,we first investigate the frequency-time-resolved photon statistical properties of resonance fluorescence from a strongly driven A-type three-level atom,and analysis their dependence on the time-ordering quantum interference.As the main result of this work,it is found that the tem-poral photon statistics of the two higher-frequency(or lower-frequency)photons emitted from two different electric dipole transitions are strongly dependent on the detection orderings.For a given detection ordering,the temporal photon statistics of these two filtered modes can be con-verted between bunching effect and antibunching effect only by adjusting the frequency of the driving laser field.The physical mechanisms are revealed that these two-mode photons partic-ipate in a pair of cascaded transition channels with opposite radiative orderings simultaneously with different dressed-state transition amplitudes,which makes them establish time-ordering quantum interference with high asymmetry.However,this characteristic of three-level system cannot appear in the widely studied two-level system and the latest four-level quantum dot.Thus,this work provides a new possible scheme for quantum manipulating of frequency-time-resolved photon statistics of resonance fluorescence.In addition to the statistical properties,more recently,the characterization and determina-tion of the nonclassical properties of radiation field have been investigated from the perspective of wave-particle duality.Along with it,the concept of "wave-particle correlation" and the cor-responding experimental schemes are proposed.However,at present,this concept is only appli-cable to two-photon regime and Gaussian states.Here,we introduce the concept of "multifold wave-particle quantum correlation" to study the nonclassical properties and the non-Gaussiality of the Mollow multiphoton states,and propose a variety of measurement schemes.It is found that,compared with the conventional criteria of nonclassicality,the proposed new criteria based on the multifold wave-particle correlation functions can determine the nonclassicality of the Mollow strongly correlated three-photon emissions in a wider parametric range.Meanwhile,we also extend the multifold wave-particle correlation functions to the time-dependent ver-sions,and find that their temporal asymmetry in the Mollow strongly correlated three-photon emissions is closely related to the non-Gaussiality.This relationship is revealed from the per-spectives of forward and backward evolutions of conditional quantum dynamics.These results may provide a new approach for the research of past-future quantum correlations and the Mol-low multiphoton physics.In the Mollow spectroscopy,the most promising photons are generated from the halfway between the central spectral band and one of the Rabi sidebands of the Mollow triplet.Photons at these frequencies can exhibit superbunching effect.In light of this,we then study the spatial directionality of the Mollow superbunching effect and its application in the precise detection in a tw o-atom radiating system via frequency-space joint resolution.In the two-atom radiating system,only one atom is dressed by a strong laser field to produce the Mollow triplet,while the other auxiliary atom is coupled with the former via the electric dipole-dipole interaction and collective spontaneous decay induced by the common electromagnetic reservoir.It is found that the two-photon strongly correlated statistics generated by frequency filtering can sensitively reflect the weak variations of the two-atom distance.In addition,the atomic coherence effect established between the two atoms not only further enhance the superbunching effect,but also endow it with prominent directionality.These results enable the two-atom radiating system to serve as the simplest quantum antenna in the Mollow spectroscopy.We then further consider the directionality of spectrally correlated nonclassical properties of resonance fluorescence from a three-body quantum antenna by synthesizing its spectral and spatial properties.In the three-body quantum antenna,two identical two-level atoms are driven by a strong laser field to generate the two-atom collective Mollow triplet,which is regulated by the third one.According to the different spectral combinations between the three-body collec-tive mode and the Mollow photons of other different frequencies,we employ different criteria of nonclassicality based on the intensity-intensity correlation function,the intensity-amplitude correlation function,and the two-mode entanglement.The results indicate that these various of nonclassical signals generated by frequency engineering can display significant spatial di-rectionality.This work reveals that the atomic coherence effect established by the collective radiative dynamics in multiatom systems play a key role in preparing the directional nonclassi-cality of collective resonance fluoresce.The proposed results and schemes of this work provide a possibility for the research and application of the geometry-dependent Mollow spectroscopy.Finally,we summarize our research works and put forward some prospects for the related issues.