Abstract In this paper, the physical origin of interferences has been explored in a four-level cascade rubidium atom by simultaneous interaction with three energies; two optical fields and one radio frequency (RF) field. The atomic system is investigated by a combination of the analytical method introduced by Zhu et al (2010 Phys. Rev. A 81 053836) and resonant pole method introduced by Anisimov (2008 J. Mod. Opt. 55 ). A substantial amount of variation in the probe absorption has been observed in various regimes. The transition from electromagnetically induced transparency (EIT) to Autler–Townes spitting (ATS) is observed. It is found that a definite threshold value exists governing the crossover from EIT to ATS. The applied analytical method gives a clear insight into the nature of interferences; one may observe EIT as a consequence of destructive interference, whereas ATS is a consequence of constructive interference. Furthermore, a transition from single EIT to double electromagnetically induced transparency has been detected when the system is illuminated by RF-driving field in weak control regime. Further, transition from ATS to double Autler–Townes splitting has been observed in the strong control regime.
Abstract In this paper, the physical origin of interferences has been explored in a four-level cascade rubidium atom by simultaneous interaction with three energies; two optical fields and one radio frequency (RF) field. The atomic system is investigated by a combination of the analytical method introduced by Zhu et al (2010 Phys. Rev. A 81 053836) and resonant pole method introduced by Anisimov (2008 J. Mod. Opt. 55 ). A substantial amount of variation in the probe absorption has been observed in various regimes. The transition from electromagnetically induced transparency (EIT) to Autler–Townes spitting (ATS) is observed. It is found that a definite threshold value exists governing the crossover from EIT to ATS. The applied analytical method gives a clear insight into the nature of interferences; one may observe EIT as a consequence of destructive interference, whereas ATS is a consequence of constructive interference. Furthermore, a transition from single EIT to double electromagnetically induced transparency has been detected when the system is illuminated by RF-driving field in weak control regime. Further, transition from ATS to double Autler–Townes splitting has been observed in the strong control regime.
Electromagnetically induced transparency (EIT) and Autler–Townes splitting (ATS) are two similar yet distinct phenomena that modify the transmission of a weak probe field through an absorption medium in the presence of a coupling field, featured in a variety of three-level atomic systems. In many applications it is important to distinguish EIT from ATS splitting. We present EIT and ATS spectra in a three-level cascade system, involving cold cesium atoms in the Rydberg state. The EIT linewidth, γ EIT , defined as the full width at half maximum of the transparency window, and the ATS splitting, γ ATS , defined as the peak-to-peak distance between AT absorption peaks, are used to delineate the EIT and ATS regimes and to characterize the transition between the regimes. In the cold-atom medium, in the weak-coupler (EIT) regime γ EIT ≈ A + B ( + , where Ω c and Ω p are the coupler and probe Rabi frequencies, Γ eg is the spontaneous decay rate of the intermediate 6P 3/2 level, and parameters A and B that depend on the laser linewidth. We explore the transition into the strong-coupler (ATS) regime, which is characterized by the relation γ ATS ≈ Ω c . The experiments are in agreement with numerical solutions of the Master equation. Our analysis accounts for non-ideal conditions that exist in typical realizations of Rydberg-EIT, including laser-frequency jitter, Doppler mismatch of the utilized two-color Rydberg EIT system, and strong probe fields. The obtained criteria to distinguish cold-atom EIT from ATS are readily accessible and applicable in practical implementations.
The A-type three-level system coupled by two coherent fields is a basic model to study the electromagnetically induced transparency(EIT).Based on that,the cascade quasi- A-four-level configuration is formed when a radio-frequency(RF)field drives the transition between the excited state and an additional excited state level.The absorption property is studied along with the parameters of the coupling field and the RF driving field by numerically solving the relevant equations of motion of the density matrix.It is shown that under the applying of the coupling field and the RF driving field,both the Autler-Townes doublet and the EIT are observed in the absorptive spectra and it can be explained properly by the theory of dressed state.An important conclusion is that the Autler-Townes doublet originates from the atom system interaction with the strong RF field,while the EIT originates from atom system quantum interference interaction with the coupling field.
Abstract Discerning electromagnetically induced transparency (EIT) from Autler–Townes splitting (ATS) is a significant issue in quantum optics and has attracted wide attention in various three-level configurations. Here we present a detailed study of EIT and ATS in a five-level atomic system considered to be composed of a four-level Y-type subsystem and a three-level Λ-type subsystem. In our theoretical calculations with standard density matrix formalism and steady-state approximation, we obtain the general analytical expression of the first-order matrix element responsible for the probe-field absorption. In light of the well-known three-level EIT and ATS criteria, we numerically show an intersection of EIT with ATS for the Y-type subsystem. Furthermore, we show that an EIT dip is sandwiched between two ATS dips (i.e., multi-dip mixture of EIT and ATS) in the absorption line for the five-level system, which can be explained by the dressed-state theory and Fano interference.
Summary form only given. If in general the transparency of an initially absorbing medium for a probe field is increased by the presence of a control field on an adjacent transition, two very different processes can be invoked to explain it. One of them is a quantum Fano interference between two paths in the three-level system, which occurs even at low control intensity and gives rise to electromagnetically-induced transparency (EIT), the other one is the appearance of two dressed states in the excited level at higher control intensity, corresponding to the Autler-Townes splitting (ATS). This distinction is particularly critical for instance for the implementation of slow light or optical quantum memories. In a recent paper, P. M. Anisimov, J. P. Dowling and B. C. Sanders proposed a quantitative test to objectively discerning ATS from EIT. We experimentally investigated this test with cold atoms and demonstrated that it is very sensitive to the specific properties of the medium. In this study, we use an ensemble of cold Cesium atoms trapped in a MOT, interacting with light via a Λ-type scheme on the D2 line. Absorption profiles are obtained for various values of the control Rabi frequency Ω between 0.1Γ and 4Γ, where Γ is the natural linewidth.
Electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS) are two similar quantum coherent phenomena but have different mechanisms and applications. Akaike information criteria (AIC), an objective method to discriminate EIT and ATS from an experimental viewpoint, has been employed in a variety of systems. Here we use AIC method to quantitively discriminate a series of spectra of cold atoms in a Rydberg-involved upper-driving ladder-type. The derived weights of EIT and ATS reflect that our spectra change from EIT-ATS intermediate region to ATS-dominated region along Rabi frequency of coupling field increases. We find that there are two factors affecting EIT-ATS weights in a Rydberg-involved three-level system: dephasing rate, induced by the interactions among Rydberg atoms, makes the EIT-ATS crossover move to the direction of low Rabi frequency of coupling field and the experimental noise makes the difference between EIT and ATS weights reduce at elsewhere. Our investigation could provide a meaningful reference for the observations and applications of Rydberg-involved quantum coherent spectroscopy.
In this work, we report on experimentally discerning Autler–Townes splitting (ATS) from electromagnetically induced transparency (EIT). Our findings are based on a Ξ (ladder) transition 5S1/2→5P3/2→5D5/2 of 87Rb atoms under different laser detuning combinations. Based on the ratio of power levels of two individual and counter-propagating lasers through a room temperature Rb vapor cell, we experiment on two different categories of Ξ configuration: types I and II. For type I, 5P3/2→5D5/2 transition is strongly driven, and we observe EIT. Type II (5S1/2→5P3/2 strongly coupled) exhibits pure ATS. Under two different two-photon detuning conditions, ATS and EIT are studied. While ATS becomes stronger near exact two-photon resonance condition, the EIT weakens. This is supported by the analysis of blue light emanating from 5D5/2→6P3/2→5S1/2 decay. The complete opposite behavior of these two phenomena at exact two-photon resonance condition can be used to clearly discern EIT from ATS.