# Number-resolved imaging of $^{88}$Sr atoms in a long working distance optical tweezer

### Submission summary

 As Contributors: Ryan Hanley · Matthew Hill · Niamh Jackson · Matthew Jones Arxiv Link: https://arxiv.org/abs/1904.03233v5 (pdf) Date accepted: 2020-02-07 Date submitted: 2020-02-03 Submitted by: Hill, Matthew Submitted to: SciPost Physics Discipline: Physics Subject area: Atomic, Molecular and Optical Physics - Experiment Approach: Experimental

### Abstract

We demonstrate number-resolved detection of individual strontium atoms in a long working distance low numerical aperture (NA = 0.26) tweezer. Using a camera based on single-photon counting technology, we determine the presence of an atom in the tweezer with a fidelity of 0.989(6) (and loss of 0.13(5)) within a 200 $\mu$s imaging time. Adding continuous narrow-line Sisyphus cooling yields similar fidelity, at the expense of much longer imaging times (30 ms). Under these conditions we determine whether the tweezer contains zero, one or two atoms, with a fidelity $>$0.8 in all cases with the high readout speed of the camera enabling real-time monitoring of the number of trapped atoms. Lastly we show that the fidelity can be further improved by using a pulsed cooling/imaging scheme that reduces the effect of camera dark noise.

Published as SciPost Phys. 8, 038 (2020)

### List of changes

Value of loss added to abstract

### Submission & Refereeing History

Resubmission 1904.03233v5 on 3 February 2020
Resubmission 1904.03233v4 on 14 January 2020
Resubmission 1904.03233v3 on 2 October 2019
Submission 1904.03233v2 on 24 April 2019