Abstract
Optical tweezers provide a versatile platform for the manipulation and detection of single atoms. Here, we use optical tweezers to demonstrate a set of tools for the microscopic control of atomic strontium, which has two valence electrons. Compared to the single-valence-electron atoms typically used with tweezers, strontium has a more complex internal state structure with a variety of transition wavelengths and linewidths. We report single-atom loading into an array of subwavelength scale optical tweezers and light-shift-free control of a narrow-linewidth optical transition. We use this transition to perform three-dimensional ground-state cooling and to enable high-fidelity nondestructive imaging of single atoms on subwavelength spatial scales. These capabilities, combined with the rich internal structure of strontium, open new possibilities including tweezer-based metrology, new quantum computing architectures, and new paths to low-entropy many-body physics.
1 More- Received 17 October 2018
- Revised 29 November 2018
DOI:https://doi.org/10.1103/PhysRevX.8.041054
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Viewpoint
Alkaline Atoms Held with Optical Tweezers
Published 28 December 2018
Three separate groups demonstrate the trapping of two-electron atoms in arrays of optical tweezers, opening up new opportunities for quantum simulation and many-body studies.
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Popular Summary
Tightly focused tweezers of laser light can be used to gain control of individual atoms at the quantum level. So far, these techniques have only been applied to relatively simple atoms that have only a single active electron. Here, we extend these techniques to a more complex atom, strontium, which has two electrons. We present techniques to cool the lonely strontium atoms into their quantum-mechanical ground state with high probability and to observe their presence with high fidelity and resolution without the tweezer heating them.
We use a relatively short-wavelength green light and a microscope with a high numerical aperture to generate the smallest tweezer foci ever used to trap single atoms. In addition, a key feature of two-electron atoms is the presence of narrow-linewidth optical transitions. We use one of these transitions to enable a robust and relatively simple method of cooling to the quantum ground state of motion and to measure the ground-state probability. This same cooling method also allows us to keep the atoms cold even while scattering hundreds of blue photons that allow us to observe the atoms with high resolution.
Strontium’s second electron, and the microscopic control that we demonstrate here, will open up grand new possibilities for quantum simulation, high-performance clockwork, and the assembly of arbitrary configurations of ground-state atoms.