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Cooling atomic ions with visible and infra-red light
摘要： We demonstrate the ability to load, cool and detect singly charged calcium ions in a surface electrode trap using only visible and infrared lasers for the trapped-ion control. As opposed to the standard methods of cooling using dipole-allowed transitions, we combine power broadening of a quadrupole transition at 729 nm with quenching of the upper level using a dipole allowed transition at 854 nm. By observing the resulting 393 nm ?uorescence we are able to perform background-free detection of the ion. We show that this system can be used to smoothly transition between the Doppler cooling and sideband cooling regimes, and verify theoretical predictions throughout this range. We achieve scattering rates which reliably allow recooling after collision events and allow ions to be loaded from a thermal atomic beam. This work is compatible with recent advances in optical waveguides, and thus opens a path in current technologies for large-scale quantum information processing. In situations where dielectric materials are placed close to trapped ions, it carries the additional advantage of using wavelengths which do not lead to signi?cant charging, which should facilitate high rate optical interfaces between remotely held ions.
关键词： trapped ions,laser cooling,quantum optics
更新于2025-09-23 15:21:21
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3D Magneto-Optical Trap of Yttrium Monoxide
摘要： We report three-dimensional trapping of an oxide molecule (YO), using a radio-frequency magneto-optical trap (MOT). The total number of molecules trapped is ～1.5 × 104, with a temperature of 4.1(5) mK. This diversifies the frontier of molecules that are laser coolable and paves the way for the second-stage narrow-line cooling in this molecule to the microkelvin regime. Futhermore, the new challenges of creating a 3D MOT of YO resolved here indicate that MOTs of more complex nonlinear molecules should be feasible as well.
关键词： laser cooling,molecular trapping,yttrium monoxide,3D magneto-optical trap
更新于2025-09-23 15:21:21
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states of Rb in simultaneous magneto-optical trapping of Rb and Hg
摘要： We report the measurement of the photoionization cross sections of the 5S1/2 and 5P3/2 states of 87Rb in a two-species Hg and Rb magneto-optical trap (MOT) by the cooling laser for Hg. The photoionization cross sections of Rb in the 5S1/2 and 5P3/2 states at 253.7 nm are determined to be 1+4.3 × 10?20 cm2 and 4.63(30) × 10?18 cm2, respectively. To measure the 5S1/2 and 5P3/2 state fractions in the MOT we detected the photoionization rate of the 5P3/2 state by an additional 401.5 nm laser. The photoionization cross section of Rb in the 5P3/2 state at 401.5 nm is determined to be 1.18(10) × 10?17 cm2.
关键词： Hg,laser cooling,Rb,magneto-optical trap,photoionization cross sections
更新于2025-09-23 15:21:01
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Towards Sympathetic Cooling of Highly Charged Ions by Laser-Cooled Ca+ Ions
摘要： The long-term goal of the Penning trap system for the heavy ion accelerator named RAON in Korea is to obtain an order of magnitude higher mass accuracy for short-lived rare isotopes. For that purpose, we are developing a sympathetic cooler for highly charged ions by exploiting laser-cooled Ca+ ions. We installed a prototype octagon chamber with a calcium atom source, a Paul trap, and a helical resonator for the high-voltage RF supply. The laser system is composed of three extended cavity diode lasers (423, 397, 866 nm) plus one UV diode laser (375 nm). The optical frequency stabilization setup is made up of a wavelength meter, a multichannel fiber switch and a PXI system with an 8-channel analog output module. After having obtained a resonant ionization signal from the calcium atomic beam, we applied the RF voltage to the trap electrodes and illuminated the cooling lasers at the center of the trap. We successfully observed a laser-cooled ion bunch and a linearly aligned ion string by using imaging optics and an electron multiplying charge coupled device (EMCCD) camera. In addition to the experimental effort, we performed a simulation study for cooling 132Sn10+ ions inside a laser-cooled 40Ca+ Coulomb crystal by using a parallel computation technique.
关键词： Ion trap,Sympathetic cooling,Laser cooling
更新于2025-09-23 15:19:57
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Combined molecular-dynamics and quantum-trajectories simulation of laser-driven, collisional systems
摘要： We introduce a combined molecular-dynamics and quantum-trajectories code to simulate the effects of near-resonant optical fields on state-vector evolution and particle motion in a collisional system. In contrast to collisionless systems, in which the quantum dynamics of multilevel, laser-driven particles with spontaneous emission can be described with the optical Bloch equations (OBEs), particle velocities in sufficiently collisional systems change on timescales comparable to those of the laser-induced, quantum-state dynamics. These transient velocity changes can cause the time-averaged velocity dependence of the quantum state to differ from the OBE solution. We use this multiscale code to describe laser cooling in a strontium ultracold neutral plasma. Important phenomena described by the simulation include suppression of electromagnetically induced transparencies through rapid velocity changing collisions and thermalization between cooled and uncooled directions for anisotropic laser cooling.
关键词： ultracold neutral plasma,molecular-dynamics,laser cooling,collisional systems,quantum-trajectories,laser-driven
更新于2025-09-23 15:19:57
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Strongly Correlated Quantum Gas Prepared by Direct Laser Cooling
摘要： We create a one-dimensional strongly correlated quantum gas of 133Cs atoms with attractive interactions by direct laser cooling in 300 ms. After compressing and cooling the optically trapped atoms to the vibrational ground state along two tightly confined directions, the emergence of a non-Gaussian time-of-flight distribution along the third, weakly confined direction reveals that the system enters a quantum degenerate regime. We observe a reduction of two- and three-body spatial correlations and infer that the atoms are directly cooled into a highly correlated excited metastable state, known as a super-Tonks-Girardeau gas.
关键词： super-Tonks-Girardeau gas,quantum gas,strongly correlated,laser cooling
更新于2025-09-23 15:19:57
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Laser-Cooled Polyatomic Molecules for Improved Electron Electric Dipole Moment Searches
摘要： Doppler and Sisyphus cooling of 174YbOH are achieved and studied. This polyatomic molecule has high sensitivity to physics beyond the Standard Model and represents a new class of species for future high-precision probes of new T-violating physics. The transverse temperature of the YbOH beam is reduced by nearly two orders of magnitude to < 600 μK and the phase-space density is increased by a factor of > 6 via Sisyphus cooling. We develop a full numerical model of the laser cooling of YbOH and ?nd excellent agreement with the data. We project that laser cooling and magneto-optical trapping of long-lived samples of YbOH molecules are within reach and these will allow a high sensitivity probe of the electric dipole moment (EDM) of the electron. The approach demonstrated here is easily generalized to other isotopologues of YbOH that have enhanced sensitivity to other symmetry-violating electromagnetic moments.
关键词： polyatomic molecules,electron electric dipole moment,laser cooling,Sisyphus cooling,YbOH
更新于2025-09-19 17:13:59
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Investigations of the possible second-stage laser cooling transitions for the holmium atom magneto-optical trap
摘要： In this work laser-spectroscopic investigations of selected electronic levels in the holmium atom are performed in the context of possible second-stage laser cooling transitions which can be considered in a magneto-optical trap. Five transitions were directly recorded by the method of laser induced fluorescence in a hollow cathode discharge. The hyperfine structure constants A and B for the upper even-parity J = 17 / 2 levels, evaluated in earlier works, were generally confirmed, and their accuracy was improved; thus the frequency differences between the hyperfine structure components, relevant for the possibility of application of the hyperfine repumping, could be determined. Investigations of the Zeeman-hyperfine structure of these spectral lines were performed in order to evaluate the Landé g J factors of the upper levels; these were reported for the first time. Semi-empirical preliminary calculations of the lifetimes of the even-parity levels in question were also carried out, allowing estimation of the expected Doppler limits for the possible narrow-band laser cooling at the respective transitions. The degree of similarity between the g J factors of the upper levels of the cooling transitions and the ground state is important for the efficiency of the sub-Doppler laser cooling in a magneto-optical trap. The results presented might facilitate the choice of the most favorable option of obtaining narrow-band laser cooling of the holmium atoms.
关键词： Landé factors,Hyperfine structure,Laser cooling,Laser spectroscopy,Holmium,Electronic levels’ lifetimes
更新于2025-09-19 17:13:59
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Laser-induced fluorescence and dispersed-fluorescence spectroscopy of the ?2E?X?2A1 transition of jet-cooled calcium methoxide (CaOCH <sub/>3</sub> ) radicals
摘要： Laser-induced fluorescence (LIF) and dispersed fluorescence (DF) spectra of the ?A2E ? ?X2A1 electronic transition of the calcium methoxide (CaOCH3) radical have been obtained under jet-cooled conditions. Complete active space self-consistent field and coupled-cluster calculations on the free radical were performed to aid the assignment of vibronic transitions observed in the LIF/DF spectra. In addition to dominant spectral features that are well reproduced by vibrational frequencies and Franck-Condon (FC) factors calculated ab initio, the FC matrix for the ?A2E ? ?X2A1 electronic transition contains considerable off-diagonal elements that connect (i) the CaO-stretch (ν4) mode and non-CaO stretch modes and (ii) the asymmetric CaOC stretch (ν3) and the CaOC bending (ν8) modes. The Jahn-Teller and pseudo-Jahn-Teller interactions involving the ?2E state as well as the spin-orbit interaction induce additional vibronic transitions that are not allowed under the Born-Oppenheimer approximation. Additionally, anharmonic vibrational terms in the ground state induce transitions that are forbidden in the harmonic-oscillator approximation. Spin-orbit splitting has been observed for several vibrational levels of the ?2E state, and an essentially constant value was measured at all levels accessed in the LIF experiment. Implications of the present spectroscopic investigation to the proposed schemes of laser-cooling MOCH3 (M = alkaline earth metals) molecules and detection of time-reversal-symmetry-violating interactions are discussed.
关键词： calcium methoxide,laser cooling,spin-orbit interaction,Jahn-Teller effect,Franck-Condon factors,vibronic transitions,CaOCH3,Laser-induced fluorescence,pseudo-Jahn-Teller effect,dispersed-fluorescence spectroscopy
更新于2025-09-19 17:13:59
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Acousto-optic modulators for a controlled frequency shift of light beams in optical and microwave cold-atom frequency standards
摘要： A series of specialised acousto-optic modulators/frequency shifters based on paratellurite (TeO2) single crystals is developed for systems of laser cooling and frequency stabilisation of laser sources in optical and microwave frequency standards based on cold strontium, rubidium and caesium atoms. The methods of calculation and optimisation of the main parameters of acousto-optic modulators are considered; their basic technical characteristics are experimentally investigated in the spectral range of optical radiation 460 – 900 nm and in the frequency shift range of 5 – 400 MHz. The modulators have a high diffraction efficiency, low power consumption and the ability to work with linearly and randomly polarised optical radiation.
关键词： frequency shifter,modulator,acousto-optic diffraction,frequency stabilisation,laser cooling,frequency shift,frequency standards
更新于2025-09-16 10:30:52