Cold highly charged ions in a radio-frequency trap with superconducting magnetic shielding

Abstract

We implement sympathetic cooling of highly charged ions (HCI) by fully enclosing a linear Paul trap within a superconducting radio-frequency resonator. A quantization magnetic field applied while cooling down into the superconducting state remains present in the trap for centuries and external electromagnetic fluctuations are greatly suppressed. A magnetic field decay rate at the 10${}^{-10}$ s${}^{-1}$ level is found using trapped Doppler-cooled Be${}^{+}$ ions as hyperfine-structure (hfs) qubits. Ramsey interferometry and spin-echo measurements on magnetically-sensitive hfs transitions yield coherence times of >400 ms, showing excellent passive shielding at frequencies down to DC. For sympathetic cooling of HCI, we extract them from an electron beam ion trap (EBIT) and co-crystallize one together with Doppler-cooled Be${}^{+}$ ions. By subsequently ejecting all but one Be${}^{+}$ ions, we prepare single HCI for quantum logic spectroscopy towards frequency metrology and qubit operations with a great variety of HCI species.

16 pages, 19 figures. The following article has been submitted to Review of Scientific Instruments. After it is published, it will be found at https://rsi.aip.org/

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Cited by in corpus (2)

• Domain formation and structural stabilities in mixed-species Coulomb crystals induced by sympathetically cooled highly charged ions
• Coulomb crystallization of xenon highly charged ions in a laser-cooled Ca+ matrix