We investigate the manipulation of the quantum interference (QI) in an electromagnetically induced transparency (EIT) system via phase fluctuations and their correlation of interacting fields. We show that the field fluctuation correlation and atomic dephasing rate have a similar effect to atomic coherence, and furthermore that QI is dependent on the fluctuation and correlation. Using the theoretical model in a dressed-state representation, the contribution of QI and Autler-Townes splitting (ATS) to probe absorption can be expressed in separate terms, such that the obvious enhancement of QI is found with highly correlated fields while ATS remains unchanged. In particular, when the relative large Rabi frequency of coupling field is applied, in which case the ATS plays a more prominent role than QI, we can still modulate the QI to be higher than ATS with correlated fields. This result could allow the strict EIT condition to be relaxed and be easily realized, or it may be a method to get a narrow EIT window for applications in efficient light storage and quantum interface.
We investigate the manipulation of the quantum interference (QI) in an electromagnetically induced transparency (EIT) system via phase fluctuations and their correlation of interacting fields. We show that the field fluctuation correlation and atomic dephasing rate have a similar effect to atomic coherence, and furthermore that QI is dependent on the fluctuation and correlation. Using the theoretical model in a dressed-state representation, the contribution of QI and Autler-Townes splitting (ATS) to probe absorption can be expressed in separate terms, such that the obvious enhancement of QI is found with highly correlated fields while ATS remains unchanged. In particular, when the relative large Rabi frequency of coupling field is applied, in which case the ATS plays a more prominent role than QI, we can still modulate the QI to be higher than ATS with correlated fields. This result could allow the strict EIT condition to be relaxed and be easily realized, or it may be a method to get a narrow EIT window for applications in efficient light storage and quantum interface.
Electromagnetically induced transparency is a quantum interference (QI) effect in a coherent system, in which the similar but distinct effect of Autler–Townes splitting (ATS) without QI also happens concurrently. The Akaike information criterion (AIC) has been proven to be an efficient and objective method to discern them by evaluating their relative AIC weights for different Rabi frequencies of the coupling field. Here, we investigate in detail the influence of the dephasing effect on the AIC weights of QI and ATS, and present the transition among destructive QI, constructive QI, and ATS without QI by controlling the dephasing rates. By comparing the effects of different dephasing rates on the QI and ATS weights, we show that the field-phase-diffusion dephasing provides more feasibility than the atom-collision dephasing in control of QI and ATS. Therefore, precise and selective dephasing engineering can be realized by manipulating the linewidths and phase correlation of the fields. This indicates that various collision-related effects (e.g., collision-dephasing-induced coherences) can be experimentally studied using more controllable field-phase-diffusion dephasing instead of buffer-gas-controlling collision dephasing.
Phenomena of electromagnetically induced transparency (PEIT) may be interpreted by the Autler-Townes Splitting (ATS), where the coupled states are split by the coupling laser field, or by the quantum destructive interference (QDI), where the atomic phases caused by the coupling laser and the probe laser field cancel. We propose modulated experiments to explore the PEIT in an alternative way by periodically modulating the coupling and the probe fields in a ?-type three-level system. Our analytical and numerical results rule out the ATS interpretation and show that the QDI interpretation is more appropriate for the modulated experiments. The proposed experiments are readily implemented in atomic gases, artificial atoms in superconducting quantum devices, or three-level meta-atoms in meta-materials.
Quantum interference effects in the unmodulated quantum systems with light-matter interaction have been widely studied, such as electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS). However, the similar quantum interference effects in the Floquet systems (i.e., periodically modulated systems), which might cover rich new physics, were rarely studied. In this article, we investigate the quantum interference effects in the Floquet two- and three-level systems analytically and numerically. We show a coherent destruction tunneling effect in a lotuslike multipeak spectrum with a Floquet two-level system, where the intensity of the probe field is periodically modulated with a square-wave sequence. We demonstrate that the multipeak split into multiple transparency windows with tunable quantum interference if the Floquet system is asynchronously controlled via a third level. Based on phenomenological analysis with Akaike information criterion, we show that the symmetric central transparency window has a similar mechanism to the traditional ATS or EIT depending on the choice of parameters, additional with an extra degree of freedom to control the quantum interference provided by the modulation period. The other transparent windows are shown to be asymmetric, different from the traditional ATS and EIT windows. These nontrivial quantum interference effects open up a scope to explore the applications of the Floquet systems.
Abstract In this letter, we theoretical investigated electromagnetically induced phase grating in a three-level quantum system. The quantum system interacts with two weak probe and signal lights and a strong coupling light. We show that in two different parametric conditions i.e. in electromagnetically induced transparency (EIT) and Autler–Townes splitting (ATS) regimes, the probe and signal beams can be diffracted into the high-order directions. We realized that in the EIT regime, some of probe energy transfer from zero order to the high orders, while in ATS regime most of probe energy transfers to the high orders and small portion remain in the zero order.
The atom-light interaction in a three-level system has shown significant physical phenomena, such as electromagnetically induced transparency and Autler{Townes splitting (ATS), for broad applications in classical and quantum information techniques. Here, we optimally demonstrated the ATS with a quantum state manipulation method. The ATS in the dephasing-dominated diamond NV center system was successfully recovered by coherent microwave control, which cannot be observed with traditional method. The dynamical process of ATS was investigated in detail, revealing a nontrivial quantum interference with geometric phase modulations. Based on the quantum interference, the signal of the optimal ATS is twice as intense as those with traditional observation method.
The appearance of quantum interference in the microscopic world is one of the deepest mysteries at the very root of quantum mechanics. When light interacts with atoms, it can induce transitions by way of distinct but indistinguishable pathways and yield unexpected and often counter-intuitive results. Electromagnetically Induced Transparency (EIT), Coherent Population Trapping (CPT), and Lasing Without Inversion (LWI) are modern examples of phenomena where the traditional rules that govern absorption and dispersion undergo major revisions. Spectacular consequences of this new state of affairs include the ability of a light beam to propagate through a normally absorbing medium with little or no absorption, or to undergo amplification even if the active medium is not prepared in a state of population inversion. Light signals have been shown to travel with strongly subluminal group velocities of only a handful of meters per second and, even, to propagate at speed greater than the ordinary speed of light, but without violation of causality or of the established rules that control the transfer of optical information through space. Three-level atoms can interact with two coherent electromagnetic fields according to three different systems, known as Cascade, Lambda and Vee systems. The propagation of a weak probe field can be deeply affected by the presence of a second stronger beam, the so-called coupling field. Transparency windows, splitting of emission and absorption lines and enormously enhanced dispersion have been documented in numerous experiments. In this thesis we explore the physical origin of the transparency induced in these systems by the simultaneous interplay of the coupling and probe fields. We focus our attention on the Cascade system and study its two configurations, Cascade-EIT and Cascade-AT. We develop a variety of complementary approaches for the description of these two configurations, some semiclassical and others fully quantum mechanical. We prove the existence of quantum interference in Electromagnetically Induced Transparency and also the surprising absence of interference in a closely related phenomenon, known as the Autler-Townes effect. Finally we complement the traditional machinery of theoretical quantum optics with techniques borrowed from quantum scattering theory, and offer what we believe is the most convincing physical evidence for the appearance, or for the absence, of quantum interference effects.