arXiv:2410.01703 · Журнал Экспериментальной и Теоретической Физики
OSTsILLYaTsII RABI PRI TREKhFOTONNOM LAZERNOM VOZBUZhDENII ODINOChNOGO RIDBERGOVSKOGO ATOMA RUBIDIYa V OPTIChESKOY DIPOL'NOY LOVUShKE
Ilya I. Beterov, Elena A. Yakshina, G. Suliman, P. I. Betleni, A. A Prilutskaya, D. A. Skvortsova, T. R. Zagirov, Denis B. Tretyakov, Vasily M. Entin, Nikolai N. Bezuglov, I. I. Ryabtsev
In an experiment on three-photon laser excitation 5S 1/2 → 5P 3/2 → 6S 1/2 → 37P 3/2 of a single 87 Rb, Rydberg atom in an optical dipole trap, we have observed for the first time three-photon Rabi oscillations between the ground and the Rydberg states. A single atom was detected optically by resonance fluorescence signal using a low-noise sCMOS video camera. The relative probability for the atom to remain in the trap after the action of three synchronized exciting laser pulses with durations varying from 100 ns to 2 µs was measured. A distinctive feature of the experiment was the use of intense laser radiation with a wavelength of 1367 nm at the second excitation step, providing a single-photon Rabi frequency up to 2 GHz to control the effective detunings of intermediate levels of the three- photon transition due to the dynamic Stark effect. Rabi oscillations with frequencies from 1 to 5 MHz were registered depending on the intensity of laser pulses of the first and second excitation steps with coherence time 0.7–0.8 µs. Ways to increase the coherence time and contrast of three-photon Rabi oscillations for applications in quantum information with Rydberg atoms are discussed.
In an experiment on three-photon laser excitation 5S 1/2 → 5P 3/2 → 6S 1/2 → 37P 3/2 of a single 87 Rb, Rydberg atom in an optical dipole trap, we have observed for the first time three-photon Rabi oscillations between the ground and the Rydberg states. A single atom was detected optically by resonance fluorescence signal using a low-noise sCMOS video camera. The relative probability for the atom to remain in the trap after the action of three synchronized exciting laser pulses with durations varying from 100 ns to 2 µs was measured. A distinctive feature of the experiment was the use of intense laser radiation with a wavelength of 1367 nm at the second excitation step, providing a single-photon Rabi frequency up to 2 GHz to control the effective detunings of intermediate levels of the three- photon transition due to the dynamic Stark effect. Rabi oscillations with frequencies from 1 to 5 MHz were registered depending on the intensity of laser pulses of the first and second excitation steps with coherence time 0.7–0.8 µs. Ways to increase the coherence time and contrast of three-photon Rabi oscillations for applications in quantum information with Rydberg atoms are discussed.
Abstract Three-photon laser excitation of single rubidium atoms in an optical dipole trap (ODT) into the 37P Rydberg state by laser radiation with wavelengths of 780, 1367, and 743 nm has been experimentally demonstrated. The excitation to Rydberg states is detected by an optical method using the losses of atoms in the ODT. The laser excitation spectra of single Rydberg atoms in the ODT are recorded, and the dependence of the excitation probability on the laser pulse duration is measured. The measured spectrum width was 2 MHz. Experiments on fluorescence quenching spectroscopy of a cloud of cold atoms in a magneto-optical trap during the three-photon laser excitation of atoms to Rydberg states are also carried out. The experimental results are compared with a numerical calculation. Methods for increasing the accuracy of the coherent three-photon laser excitation of Rydberg atoms in the ODT are considered.
Three-photon laser excitation of single rubidium atoms in an optical dipole trap (ODT) into the37P Rydberg state by laser radiation with wavelengths of 780, 1367, and 743 nm has been experimentally demonstrated. The excitation to Rydberg states is detected by an optical method using the losses of atoms in the ODT. The laser excitation spectra of single Rydberg atoms in the ODT are recorded, and the dependence of the excitation probability on the laser pulse duration is measured. The measured spectrum width was 2MHz. Experiments on fluorescence quenching spectroscopy of a cloud of cold atoms in a magneto-optical trap during the three-photon laser excitation of atoms to Rydberg states are also carried out. The experimental results are compared with a numerical calculation. Methods for increasing the accuracy of the coherent three-photon laser excitation of Rydberg atoms in the ODT are considered.
The spectra of three-photon laser excitation (according to the 5 S 1/2 → 5 P 3/2 → 6 S 1/2 → 37 P 3/2 scheme) of mesoscopic ensembles of cold Rb Rydberg atoms in a magneto-optical trap, using cw single-frequency lasers in each stage, have been investigated. The ensembles consisted of 1 to 5 atoms, and their presence was recorded by the selective field ionisation method with postselection according to the number of atoms. The dependence of the spectral shape on the excitation laser pulse duration has been studied. For 2-μs pulses, the minimum spectral width was found to be 1.3 MHz; it was determined by the laser linewidth and the spectral width of laser pulse. For pulses shorter than 0.5 μs, additional spectral broadening and occurrence of Rabi oscillations in the wings of three-photon resonances have been observed, a fact indicative of implementation of coherent three-photon laser excitation of Rydberg atoms. An analysis of the spectra within the four-level theoretical model based on optical Bloch equations showed good agreement between the experimental and theoretical results. The dependence of the shape of three-photon excitation spectrum on the number of recorded atoms was also studied. An increase in the average number of atoms leads to the occurrence of a dip in the single-atom excitation spectra; this dip is due to the specificity of the excitation and detection statistics of Rydberg atoms. The results obtained are important for applications of Rydberg atoms in quantum informatics.
Abstract The temporal dynamics of three-photon 5S1/2 → 5P3/2 → 6S1/2 → 39P3/2 laser excitation of mesoscopic ensembles of cold Rb atoms to Rydberg states in a magneto-optical trap is studied using cw single-frequency lasers at each stage. The ensembles comprise N = 1 – 5 atoms and are detected by the method of selective field ionisation with postselection with respect to the number of atoms. The dependence of the excitation probability on the duration of the exciting laser pulses and the number of detected Rydberg atoms is investigated. At short interaction times, a linear increase in probabilities is observed, and at large times, the probabilities reach saturation, while each number of atoms has its own characteristic features. The experimental dependences are compared with the results of numerical calculations in the framework of a four-level model, and their good agreement is obtained. The conditions necessary for observing Rabi population oscillations are determined. The obtained results are important for the application of Rydberg atoms in quantum information.
Abstract The results of experiments on the implementation of single-qubit quantum gates with a single 87Rb atom in an optical dipole trap with a wavelength of 850 nm are presented. The trap is formed by a long focal-length objective lens located outside the vacuum chamber of a magneto-optical trap. An atom is detected using a resonance fluorescence signal with an sCMOS video camera. The experiments involved the trapping and confinement of a single atom at times up to 50 s, optical pumping by polarized laser radiation, microwave transitions between two hyperfine sublevels of the ground state, and the measurement of the quantum state of the atom by pushing it from the trap. Rabi oscillations are observed during the “clock” microwave transition 5S1/2(F = 2, MF = 0) → 5S1/2(F = 1, MF = 0) between two operating qubit levels at a frequency of up to 4.2 kHz, a contrast of up to 95%, and a coherence time of up to 3 ms. These oscillations correspond to the implementation of two basic single-qubit quantum operations (Hadamard gate, NOT gate) from various initial qubit states with an average fidelity of 95.2 ± 3%.
Single-atom-based single-photon source has several advantages, such as narrow bandwidth, wavelength matching with the absorption line of the same atomic ensemble, and insensitivity to the environment disturbing, and it is very important not only for basic researches in quantum optic field but also for applications in quantum information processing. In this paper, we report the generation of a 10-MHz-repetition-rate triggered single-photon source at 852 nm based on a trapped single cesium atom in a far-off-resonance microscopic optical dipole trap (FORT). To generate an optical dipole trap, a far-red-detuned 1064 nm laser beam is tightly focused by using a high numerical aperture lens, a typical trap depth is 2 mK and trap waist is 2.3 m. To obtain a maximum probability of pulsed excitation, the frequency of the pulsed laser should be resonant with the atomic energy levels and the trapped single atom must be excited with a -pulse. However, the interaction between the FORT laser and the atoms causes AC Stark shifts of the atomic energy levels. Thus, in order to demonstrate the resonant pulsed excitation, it is important to calculate and measure the shift of 6S1/2|Fg=4,mF=+4-6P3/2|Fe=5,mF=+5 cyclical transition in the FORT. For a two-level system, the probability of pulsed excitation can be described by Rabi oscillations with a characteristic Rabi frequency . With an optimized time sequence, we experimentally demonstrate the Rabi oscillation between the ground state and the excited state, and the peak power of -pulse laser is about 1.25 mW. We also measure the temporal envelope of single photons after a -pulse excitation. A gated pulsed excitation and cooling technique are used to reduce the possibility that atoms are heated by -pulse laser. The typical trapping lifetime of single cesium atom is extended from~108 ups to~2536 ms. The corresponding number of excitations is improved from 108 to 360000. The second-order intensity correlations of the emitted single-photon are characterized by implementing Hanbury Brown-Twiss setup. The statistics shows a strong anti-bunching with a value of 0.09 for the second-order correlation at zero delay. In the future, we will perform a Hong-Ou-Mandel two-photon interference experiment to analyze the indistinguishability of the single photons. We will also trap single atoms in a magic-wavelength optical dipole trap where the ground and the excited states have the same shift.