<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mmultiscripts> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi>In</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> <mml:mprescripts/> <mml:none/> <mml:mrow> <mml:mn>115</mml:mn> </mml:mrow> </mml:mmultiscripts> <mml:mtext>−</mml:mtext> <mml:mrow> <mml:mmultiscripts> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi>Yb</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> <mml:mprescripts/> <mml:none/> <mml:mrow> <mml:mn>172</mml:mn> </mml:mrow> </mml:mmultiscripts> </mml:mrow> </mml:mrow> </mml:math> Coulomb Crystal Clock with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mn>2.5</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>18</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> Systematic Uncertainty
H. N. Hausser, Jonas Keller, T. Nordmann, N. M. Bhatt, J. Kiethe, H. Liu, I. M. Richter, Moritz von Boehn, Johannes Rahm, S. Weyers, Erik Benkler, B. Lipphardt, Sören Dörscher, K.A. Stahl, J. Klose, Christian Lisdat, Melina Filzinger, Nils Huntemann, E. Peik, T. E. Mehlstäubler
Abstract
We present a scalable mixed-species Coulomb crystal clock based on the ^{1}S_{0}↔^{3}P_{0} transition in ^{115}In^{+}. ^{172}Yb^{+} ions are cotrapped and used for sympathetic cooling. Reproducible interrogation conditions for mixed-species Coulomb crystals are ensured by a conditional preparation sequence with permutation control. We demonstrate clock operation with a 1In^{+}-3Yb^{+} crystal, achieving a relative systematic uncertainty of 2.5×10^{-18} and a relative frequency instability of 1.6×10^{-15}/sqrt[τ/1 s]. We report on absolute frequency measurements with an uncertainty of 1.3×10^{-16} and optical frequency comparisons with clocks based on ^{171}Yb^{+} (E3) and ^{87}Sr. With a fractional uncertainty of 4.4×10^{-18}, the former is-to our knowledge-the most accurate frequency ratio value reported to date. For the ^{115}In^{+}/^{87}Sr ratio, we improve upon the best previous measurement by more than an order of magnitude. We also demonstrate operation with four ^{115}In^{+} clock ions, which reduces the instability to 9.2×10^{-16}/sqrt[τ/1 s].