Resolved-Sideband Laser Cooling in a Penning Trap

Abstract

We report the laser cooling of a single ^{40}Ca^{+} ion in a Penning trap to the motional ground state in one dimension. Cooling is performed in the strong binding limit on the 729-nm electric quadrupole S_{1/2}↔D_{5/2} transition, broadened by a quench laser coupling the D_{5/2} and P_{3/2} levels. We find the final ground-state occupation to be 98(1)%. We measure the heating rate of the trap to be very low with n[over ¯][over ˙]≈0.3(2) s^{-1} for trap frequencies from 150-400 kHz, consistent with the large ion-electrode distance.

Sideband cooling of the radial modes of motion of a single ion in a Penning trap

“…Sideband cooling from outside the Lamb-Dicke regime is still possible, but requires the addressing of higher order motional sidebands to prevent any accumulation of population in any of the coupling minima. This has been shown previously in RF traps [54,55] as well as in our Penning trap for the axial motion of single ions [8] and small Coulomb crystals [50]. In fact, cooling the axial modes of a two-ion chain at low trap frequency is similar to the problem of cooling the two radial modes of a single ion in that both require addressing higher order sidebands of both motions in turn.…”

“…Radial Doppler spectrum with ν + = 677 kHz, ν − = 52 kHz taken with 1 V axialization. Full fit to two-mode Rabi dynamics gives the mean phonon numbersn + = 96(5) andn − = 136(8) and Ω 0 /2π = 26 kHz…”

Sympathetic cooling of protons and antiprotons with a common endcap Penning trap

“…Doppler cooled ions, for example, at sub mK temperatures, are the foundation of successful trapped ion quantum information experiments (25)(26)(27). Likewise ions in rf traps (28), and more recently Penning traps (29), are routinely prepared in the ground state. Similarly, sympathetic cooling, in which a laser cooled ion couples via the Coulomb interaction to another ion without a suitable cooling transition, has been demonstrated for a variety of ions (30)(31)(32) and implemented for modern metrology and spectroscopy experiments (33).…”

The TRAPSENSOR facility: an open-ring 7 tesla Penning trap for laser-based precision experiments

“…Its subsequent application as a high-sensitive sensor will enable precision experiments in the framework of nuclear and fundamental physics. Reaching the quantum regime, by performing ground-state cooling in 7 tesla would only require one extra laser with λ=729nm, thus not introducing more complexity compared to such kinds of experiments in B=1.86 tesla [66]. The implementation of such cooling mechanism will be also interesting in the field of quantum technologies, for example for digital-analog quantum simulations of spin models as Heisenberg [67], or spin-boson models as the Dicke model, in a variety of coupling regimes and inhomogeneities.…”