DOI: 10.7795/720.20250315
title: Additional data for the publication "Long-distance chronometric leveling with a portable optical clock"

description: We have measured the geopotential difference between two locations separated by 457 km by comparison of two optical lattice clocks via an interferometric fiber link, utilizing the gravitational redshift of the clock transition frequency. The 87⁢Sr clocks have been compared side-by-side before and after one of the clocks was moved to the remote location. The chronometrically measured geopotential difference of 3918.1⁢(2.6) ⁢m2 s−2 agrees with an independent geodetic determination of 3915.88⁢(0.30) ⁢m2 s−2. The uncertainty of the chronometric geopotential difference is equivalent to an uncertainty of 27 cm in height.
description: <b>[date:yyyymmdd]_[campaign].csv</b>: Fractional frequency difference between the stationary clock Sr1 and the transportable clock Sr2. Source data of the Allan deviations shown in Fig. 2 and Fig. 4 of the manuscript.""
 method: Experimental data. Optical beat frequency between clock lasers recorded by dead-time-free counters, with known radio frequency offsets removed.
 Includes systematic corrections of the clocks. For local campaigns only, includes local gravitational redshift difference between the clocks.
 format: text/csv
 recommended software: [Python](https://www.python.org/)
 parameters: &gt;
 One file per date, with additional label to identify the campaign (`local1`, `remote`, or `local2`).
 Each row represents an interval of 1 s duration. Timestamps and gaps removed. Counters operated in lambda mode.

<b>ratio_data.csv</b>: Daily mean values and uncertainties of the fractional frequency difference between the stationary clock Sr1 and the transportable clock Sr2.
 The 3rd to the 12th columns denote the following:
 * Daily clock ratio "Sr2-Sr1"
 * Statistical uncertainty "u_stat"
 * Systematic uncertainty of Sr2 without the lattice light shift uncertainty "u_Sr2_noL"
 * Lattice light shift uncertainty of Sr2 "u_Sr2_L"
 * Total systematic uncertainty of Sr2 "u_Sr2"
 * Systematic uncertainty of Sr1 without the lattice light shift uncertainty "u_Sr1_noL"
 * Lattice light shift uncertainty of Sr1 "u_Sr1_L"
 * Total systematic uncertainty of Sr1 "u_Sr1"
 * Uncertainty of the gravitational redshift difference "u_grav"
 * Total uncertainty of the daily clock ratio "u_tot"
 Some of these data are shown in Fig. 3 of the manuscript (black data points: "Sr2-Sr1", black error bars: "u_tot", golden error bars: "u_stat").
 method: Aggregate experimental data, see above.
 format: "text/csv (with semicolon as separator)"
 recommended software: [Python](https://www.python.org/)
 parameters: "not applicable"
description: We acknowledge support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy -- EXC-2123 QuantumFrontiers -- Project-ID 3908379.67.
We acknowledge support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under SFB~1464 TerraQ -- Project-ID 434617780 -- within projects A04 and A05.
We acknowledge support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under SFB~1128 geoQ within projects A03 and A04.
This work was partially supported by the Max Planck--RIKEN--PTB Center for Time, Constants and Fundamental Symmetries.