Detection of a single lithium atom in a magneto-optical trap

Hyok Sang Han, Seokchan Yoon, Donghyun Cho

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


We report fluorescence detection of a single <sup>7</sup>Li atom in a magneto-optical trap (MOT). We use a double MOT system, which allows us to control the loading rate of the second MOT by simply turning on or off the first MOT and to use a modest magnetic field gradient of 46 G/cm. A single atom is trapped for longer than 100 s. The fluorescence from the trapped atoms is imaged onto an electron-multiplying charge-coupled device with a unit magnification factor by a pair of aspheric lenses. The numerical aperture of the objective lens is 0.22 with a collecting efficiency of 1.3%. Accumulated fluorescence is extracted by integrating the signal over a region of interest of 500×350 μm<sup>2</sup>. For a 200-ms exposure time, the fluorescence count from a single atom is 8.8×10<sup>3</sup> and the background count from scattered MOT beams is 6.8 × 10<sup>4</sup>. We actively stabilize the trap beam power to reduce the noise and the measured noise is two times the statistical noise. Overall signal-to-noise ratio of the single-atom detection is 37/√ Hz. We also describe a modification of the system that is adapted to an experimental configuration for quantum manipulation of single atoms in a 1D optical lattice.

Original languageEnglish
Pages (from-to)1675-1679
Number of pages5
JournalJournal of the Korean Physical Society
Issue number11
Publication statusPublished - 2015 Jun 20


  • Lithium atom
  • Magneto-optical trap
  • Single-atom detection

ASJC Scopus subject areas

  • General Physics and Astronomy


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