Abstract We demonstrate the effect of inter-atomic interaction in highly excited Rydberg atoms via Autler–Townes (AT) splitting in cold atoms. We measure the AT splitting of the { 5 S 1 / 2 , F = 2 } → { 5 P 3 / 2 , F ′ = 3 } transition of 87Rb atoms arising due to the strong coupling of the transition via the cooling beams used for the magneto-optical trap (MOT). The AT splitting is probed using a weakly coupled transition from { 5 P 3 / 2 , F ′ = 3 } state to highly excited Rydberg states for a wide range of principal quantum numbers ( n = 35 − 117 ) . We observe the AT splitting via trap-loss spectroscopy in the MOT by scanning the probe frequency. We observe a drastic increase in the broadening of the AT splitting signal as a result of interaction-induced dephasing effect in cold Rydberg atoms for highly excited Rydberg states with principal quantum number n > 100. We explain our observations using theoretical modeling and numerical simulations based on the Lindblad Master equation. We find a good agreement of the results of the numerical simulation with the experimental measurements.
Abstract We demonstrate the effect of inter-atomic interaction in highly excited Rydberg atoms via Autler–Townes (AT) splitting in cold atoms. We measure the AT splitting of the { 5 S 1 / 2 , F = 2 } → { 5 P 3 / 2 , F ′ = 3 } transition of 87Rb atoms arising due to the strong coupling of the transition via the cooling beams used for the magneto-optical trap (MOT). The AT splitting is probed using a weakly coupled transition from { 5 P 3 / 2 , F ′ = 3 } state to highly excited Rydberg states for a wide range of principal quantum numbers ( n = 35 − 117 ) . We observe the AT splitting via trap-loss spectroscopy in the MOT by scanning the probe frequency. We observe a drastic increase in the broadening of the AT splitting signal as a result of interaction-induced dephasing effect in cold Rydberg atoms for highly excited Rydberg states with principal quantum number n > 100. We explain our observations using theoretical modeling and numerical simulations based on the Lindblad Master equation. We find a good agreement of the results of the numerical simulation with the experimental measurements.
We study the effects of Rydberg-atom interactions on Autler-Townes (AT) spectra in a dense gas of ultracold cesium atoms. The 6S1/2 and 6P3/2 levels of cesium are strongly coupled (Rabi frequency ${\ensuremath{\Omega}}_{c})$, and the resultant AT spectra are probed via excitation into a Rydberg level. Van der Waals interactions between the atoms in the probe Rydberg level give rise to a dephasing rate $({\ensuremath{\gamma}}_{3})$. The interaction-induced dephasing is found to cause characteristic changes in the AT spectra, including a reduction or elimination of the AT splitting, an increase in the critical ${\ensuremath{\Omega}}_{c}$ above which AT splitting occurs, and an increase in the width of the AT spectral lines. Rydberg-atom interactions are controlled by varying the principal quantum number n of the probe Rydberg level; larger values of n correspond to higher dephasing rates ${\ensuremath{\gamma}}_{3}$. Results of numerical calculations are in good agreement with the experiments.
Autler-Townes (A-T) splitting, known as an AC Stark effect, shows a change of an absorption/emission spectral line of a probe beam when an oscillating field is tuned in resonance with the atomic or molecular transition. The A-T splitting is observed in different three-level atoms and widely investigated in a vapor cell and in a magneto-optical trap (MOT). The A-T splitting plays an important role in the atom-based microwave electric-field measurements where a cascade three-level system involving Rydberg state is adopted. In this work, an A-T splitting is observed in an ultracold cesium Rydberg gas, which is cooled down to about 100 pK and center density is about 1010 cm-3 in a conventional MOT by using the laser cooling technology. We present the A-T spectrum in a ladder three-level atomic system involving a 34D5/2 Rydberg state. The cesium ground state (6S1/2), excited state (6P3/2) and Rydberg state (34D5/2) constitute a Rydberg three-level system. A coupling laser, locked to the Rydberg transition by using a Rydberg electromagnetically induced transparency signal that is obtained from a cesium room-temperature vapor cell, couples 6P3/2 (F'=5) 34D5/2 Rydberg transition. A weak probe laser, stabilized to a ground-state transition by using a polarization spectroscopy, is swept, covering the transition 6S1/2 (F=4) 6P3/2 (F'=5) with a double-passed acousto-optic modulator. The probe and coupling lasers are counter-propagated through the MOT center. The power of probe light is 200 pW, corresponding Rabi frequency p=21.05 MHz. During the experiment, 50 s after turning off the trapping laser, both the coupling and probe beams are switched on and last 100 s. The A-T spectrum as a function of the probe detuning is detected with a single-photon counter module detector. We use Gaussian multiple peak fitting to obtain the positions of the A-T peaks and the A-T splitting. The measured A-T splitting is proportional to the Rabi frequency of the coupling light. We numerically solve the density matrix equations to obtain the A-T spectrum, and the calculations reproduce A-T spectra well. The measured A-T splitting shows good agreement with the theoretical calculation for Rabi frequency of the coupling light c29 MHz. The A-T splitting is less than the calculation for the case of c29 MHz, the deviation is mainly attributed to the increased dephasing rate induced by the strong interaction between Rydberg atoms, whose number increases with the coupling laser Rabi frequency. In this work, the adopted method for the cascade three-level system involving Rydberg state is also suitable for -and V-type cases.
In this article, effects of the strong long-range interaction of Rydberg atoms on the Autler–Townes splitting spectrum are investigated. Preliminary results are obtained for various excitation times and Rydberg atom densities. The 2S1/2 and 2P1/2 levels of lithium-7 are coupled with strong laser field and probed by another laser via excitation into a 70S Rydberg level. Interactions between Rydberg atoms excited by the probe beam lead to the broadening of the Autler–Townes spectra. At high concentrations of Rydberg atoms, a suppression of the excitation of the Autler–Townes peak at red detuning is observed.
We experimentally investigate trap-loss spectra of the cesium 6S1/2(F = 4) → 71P3/2 Rydberg transition by combining the cesium atomic magneto-optical trap with the narrow-linewidth, continuously tunable 318.6 nm ultraviolet laser. Specifically, the atoms in the magneto-optical trap are excited to the Rydberg state due to the ultraviolet laser single-step Rydberg excitation, which leads to the reduction of atomic fluorescence. Based on the trap-loss spectroscopy technology, the Autler–Townes (AT) splitting due to a strong cooling laser is observed, and the parameter dependence of the AT splitting interval of trap-loss spectroscopy is investigated. The effective temperature of cold atoms is measured by using simplified time-of-flight fluorescence imaging. In addition, closed-loop feedback power stabilization of 318.6 nm ultraviolet laser is carried out. This lays the foundation for further experimental research related to the Rydberg atoms using ultraviolet lasers, which is of great significance for the development of quantum computing and quantum information.
Autler-Townes (AT) splitting is observed in ultracold cesium Rydberg gases. Frequency and power of the laser field coupling 6S1/2 and 6P3/2 levels are tuned to influence the population redistribution of 6P3/2 and nS levels excited by another light. The profile of AT spectroscopy is measured experimentally and compared with the theoretical simulation considering the estimated large dephasing rates caused by interaction between Rydberg atoms, which demonstrates that splitting and profile of AT spectra are strongly dependent on the interaction between Rydberg atoms. Rabi frequency of the coupling laser and transition dipole moment of 6S${}_{1/2}\ensuremath{\rightarrow}$ 6P3/2 are deduced via fitting the measured space variation of two splitting peaks, which is consistent with theoretical calculations.
We demonstrate the three-photon Autler-Townes (AT) spectroscopy in a cold cesium Rydberg four-level atom by detecting the field ionized Rydberg population. The ground state |6S1/2〉, two intermediate states |6P3/2〉 and |7S1/2〉 and Rydberg state |60P3/2〉 form a cascade four-level atomic system. The three-photon AT spectra and AT splittings are characterized by the Rabi frequency Ω852 and Ω1470 and detuning δ852 of the coupling lasers. Due to the interaction of two coupling lasers with the atoms, the AT spectrum has three peaks denoted with the letters A, B and C. Positions of the peaks and relative AT splittings, γAB and γBC, strongly depend on two coupling lasers. The dependence of the AT splitting, γAB and γBC, on the coupling laser detuning, δ852, and Rabi frequency, Ω852 and Ω1470 are investigated. It is found that the AT splitting γAB mainly comes from the first photon coupling, whereas the γBC mainly comes from the second photon coupling with the atom. The three-photon AT spectra and relevant AT splittings are simulated with the four-level density matrix equation and show good agreement with the theoretical simulations considering the spectral line broadening. Our work is of great significance both for further understanding the interaction between the laser and the atom, and for the application of the Rydberg atom based field measurement.