Two-photon cooling of calcium atoms

Abstract

We demonstrate sub-Doppler cooling of calcium atoms using a two-photon transition from the ${}^1{S}_0$ ground state to the upper $4s5s{}^1{S}_0$ state via the ${}^1{P}_1$ intermediate state. We achieve temperatures as low as $260\mu \text{K}$ in a magneto-optical trap (MOT), well below the Doppler limit ($T_{\text{D}}=0.8\text{mK}$) of the ${}^1{P}_1$ state. We characterize temperature, lifetime and confinement of the MOT over a range of experimental parameters, observing no reduction in lifetime due to coupling to the higher state. We perform theoretical simulations of the cooling scheme and observe good agreement with the experimental results. The two-photon cooling scheme presented in this work provides an alternative to the standard Doppler cooling applied to alkaline-earth atoms, based on a sequence of two magneto-optical traps. The advantages of our scheme are the possibility of varying the effective linewidth of the ${}^1{P}_1$ state, a higher transfer efficiency (close to 100$\%$), and a more straightforward experimental implementation.

8 pages 4+1 figures

References in corpus (31)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• QuTiP: An open-source Python framework for the dynamics of open quantum systems
• High-Fidelity Entanglement and Detection of Alkaline-Earth Rydberg Atoms
• JILA SrI Optical Lattice Clock with Uncertainty of $2.0\times 10^{-18}$
• High-fidelity gates with mid-circuit erasure conversion in a metastable neutral atom qubit
• Alkaline earth atoms in optical tweezers
• Erasure conversion for fault-tolerant quantum computing in alkaline earth Rydberg atom arrays
• Microscopic control and detection of ultracold strontium in optical-tweezer arrays
• Doppler cooling and trapping on forbidden transitions
• Narrow-line cooling and imaging of Ytterbium atoms in an optical tweezer array
• Erasure conversion in a high-fidelity Rydberg quantum simulator
• Universal gate operations on nuclear spin qubits in an optical tweezer array of ${}^{171}$Yb atoms
• Quenched Narrow-Line Laser Cooling of 40Ca to Near the Photon Recoil Limit
• Trapped arrays of alkaline earth Rydberg atoms in optical tweezers
• On the feasibility of cooling and trapping metastable alkaline-earth atoms
• A simplified 461-nm laser system using blue laser diodes and a hollow cathode lamp for laser cooling of Sr
• Controlling Rydberg excitations using ion core transitions in alkaline earth atom tweezer arrays
• Narrow-line Laser Cooling by Adiabatic Transfer
• Quenched narrow-line second- and third-stage laser cooling of 40Ca
• Long-Lived Circular Rydberg Qubits of Alkaline-Earth Atoms in Optical Tweezers
• Three dimensional cooling and trapping with a narrow line
• Fast and dense magneto-optical traps for Strontium
• Two-Photon Doppler cooling of alkaline-earth-metal and ytterbium atoms
• Motional ground-state cooling of single atoms in state-dependent optical tweezers
• Improved magneto-optical trapping of Ca
• Optical coherent manipulation of alkaline-earth circular Rydberg states
• Two-photon and EIT-assisted Doppler cooling in a three-level cascade system
• On the Roles of the Secondary Circulation in the Formation of Hurricanes
• Coherent Quantum Engineering of Free-Space Laser Cooling
• Searching for New Fundamental Interactions via Isotopic Shifts in Molecular Lattice Clocks
• Quadrupole coupling of circular Rydberg qubits to inner shell excitations