Trapping and cooling of Sr⁺ions: strings and large clouds

Abstract

ParisDiderot-Paris 7 -Large and cold ion clouds are very promising media for quantum information processing and quantum memories [1,2]. We report on the trapping and laser cooling of large clouds of singly ionized strontium ions in a linear Paul trap. We describe our loading technique based on two-photon absorption of femtosecond pulses and compare it to electron-bombardment ionization. The sample are Doppler-cooled to form Coulomb crystals both in the few-ion regime and in the case of large clouds. Our setup is designed, in particular, to obtain optically dense clouds in the perspective of an ion-based quantum memory for continuous variables [2]. We present absorption measurements, that are consistent with the estimated number of ions present in the trap. These experiments open the way to the use of a large cold trapped-ion cloud for the realization of a long-lived quantum memory.

Optical pulse-shaping for internal cooling of molecules

“…To this end, various approaches involving state-selective resonance-enhanced multi-photon dissociation (REMPD) [10,11] and chemical reactions [14] have been used. We intend to use an already demonstrated method for state readout that counts the number of state-selectively photodissociated ions by sequentially dumping different species from the trap onto a detector [30]. AlH + ions in a specific rotational state of X 2 Σ + (v = 0) will be optically excited to A 2 Π(v = 0) with a tunable pulsed dye laser at a wavelength of 360 nm, and then excited to a dissociating state (3 2 Σ + ) with a 266 nm pulse generated from the 4th-harmonic of a Nd:YAG laser.…”

“…The Al + ions can then be extracted and counted, by applying a resonant radial secular excitation, which causes Al + to be transferred to an ion guide leading to a micro-channel plate (MCP). The secular excitation is mass-selective and can extract only the daughter ions without extracting the non-dissociated parent ions [30].…”

Cold neutral atoms via charge exchange from excited state positronium: a proposal

“…While constituting a realistic set of trapping parameters which enables trapping of order 10 3 ions and forming Coulomb crystals at temperatures near 5 mK, we note that further optimisation may be required in an experiment. We also note that very large numbers of ions are in principle available, e.g., 9 10 4 ions have been reported [50].…”

Extending Our Knowledge about the 229Th Nuclear Isomer

“…The lack of hyperfine-structure shifts in 88 Sr ions provides a simpler cooling scheme than for 229(m) Th 3+ . Doppler cooling can be performed on the 2 S 1/2 → 2 P 1/2 transition at 422 nm [20]. The ions are re-pumped from the 2 D 3/2 to the 2 P 1/2 state with 1091 nm radiation (see the left part of Figure 2).…”