A cryogenic radio-frequency ion trap for quantum logic spectroscopy of highly charged ions

Abstract

A cryogenic radio-frequency ion trap system designed for quantum logic spectroscopy of highly charged ions is presented. It includes a segmented linear Paul trap, an in-vacuum imaging lens and a helical resonator. We demonstrate ground state cooling of all three modes of motion of a single 9 Be + ion and determine their heating rates as well as excess axial micromotion. The trap shows one of the lowest levels of electric field noise published to date. We investigate the magnetic-field noise suppression in cryogenic shields made from segmented copper, the resulting magnetic field stability at the ion position and the resulting coherence time. Using this trap in conjunction with an electron beam ion trap and a deceleration beamline, we have been able to trap single highly charged Ar 13+ (Ar XIV) ions concurrently with single Be + ions, a key prerequisite for the first quantum logic spectroscopy of a highly charged ion.

Coherent laser spectroscopy of highly charged ions using quantum logic

“…to 100 9 Be + ions that has been previously loaded into the Paul trap by means of laser ablation combined with photoionisation 34 (see also Fig. 1).…”

Closed-cycle, low-vibration 4 K cryostat for ion traps and other applications

“…1) extends over two rooms which are separated by an acoustically insulating wall. One of them is the laser laboratory, in which the experimental chamber, containing a linear Paul trap 56 , is rigidly mounted on top of a pneumatically floating optical table to decouple it from the floor. Although this cryogenic system was intended for use with an ion trap, any object of study could be cooled with it.…”

“…II D 3). This tube passes through the 350-mm diameter hole in the optical table and is connected to the bottom of the iontrap chamber 56 . For balancing the compressive forces, two edge-welded DN160CF bellows with 20 diaphragm pairs are mounted to the outer flanges of each of the two six-way crosses.…”

“…The dominant heat load onto the first stage is the thermal radiation, while for the second stage the thermal conduction is dominant. Additional heat loads onto the first and second stages are introduced by thermal radiation from the ion trap chamber, conduction through further spokes and the rf ion trap wiring, and dissipation of rf power 56 . Thus, we reach final temperatures of 33.8 K at the pulse-tube first stage and of 3.50 K at the second stage, respectively.…”

“…It is already in operation for studying forbidden optical transitions of HCIs. These are produced by a Heidelberg Compact Electron Beam Ion Trap (HC-EBIT) 55 , transferred through an ion beamline, decelerated, and retrapped in a cryogenic Paul trap 56 .…”