# 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/1904.03233v4 (pdf) Date submitted: 2020-01-14 01:00 Submitted by: Hill, Matthew Submitted to: SciPost Physics Academic field: Physics Specialties: 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) 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.

###### Current status:
Has been resubmitted

Please see responses to referees for changes.

### List of changes

Please see responses to referees for changes.

### 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

## Reports on this Submission

### Anonymous Report 2 on 2020-1-23 Invited Report

• Cite as: Anonymous, Report on arXiv:1904.03233v4, delivered 2020-01-23, doi: 10.21468/SciPost.Report.1469

### Report

The authors have substantially improved the calculation and discussion of imaging fidelity. My one remaining request would be to mention in the abstract the degree of loss associated with the quoted fidelity. Generally, loss and fidelity limit the performance of an experiment in a similar manner, so it is important to know both. In particular, past experiments have typically optimized for simultaneously low loss and high fidelity, so knowing both numbers is critical for comparison. If loss is not mentioned, the reader may assume that it has been included in the definition of fidelity. Apart from that small but I think important point, I now recommend the manuscript for publication.

### Requested changes

see above

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### Report

I am satisfied with the authors' response to my previous comments, and I now recommend publication.

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