SAMOP 2023 – scientific programme
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QI: Fachverband Quanteninformation
QI 18: Quantum Technologies: Trapped Ions (joint session Q/QI)
QI 18.6: Talk
Wednesday, March 8, 2023, 12:15–12:30, F342
Sideband Thermometry on Ion Crystals — •Ivan Vybornyi1, Laura Dreissen2, Daniel Vadlejch2, Tanja Mehlstäubler2, and Klemens Hammerer1 — 1Institut für theoretische Physik, Leibniz Universität Hannover, Appelstraße 2,30167 Hannover, Germany — 2Physikalisch-Technische Bundesanstalt, Bundesallee 100,308116 Braunschweig, Germany
Crystals of ultracold trapped ions reach sizes of hundreds of individual particles and require high level of control over their motional temperature to account for the second-order Doppler shift in clocks and implement high-fidelity quantum gates in quantum computers. The existing thermometry tools fail to provide an accurate temperature estimation for large ground-state cooled crystals, either focusing only on the symmetric c.o.m. mode of motion or neglecting the involved spin-spin correlations between the ions.
To resolve the thermometry large-N bottleneck, we consider crystal many-body dynamics arising when motional sideband transitions are driven in a near ground-state regime, which is a widely used approach in thermometry of a single ion. To gain some valuable insights on the sideband thermometry method, we also address the single ion case and study it from the Fisher Information prospective.
Extending the approach further, we account for entanglement created between the ions in a crystal to derive a new reliable temperature estimator, insensitive to the number of ions, and field-test in experiments with 4- and 19-ion crystals done by colleagues from PTB and Innsbruck.