Motional studies of one and two laser-cooled trapped ions for electric-field sensing applications

Abstract

We have studied the dynamics of one and two laser-cooled trapped 40 Ca + ions by applying electric fields of different nature along the axial direction of the trap, namely, driving the motion with a harmonic dipolar field, or with white noise. These two types of driving induce distinct motional states of the axial modes; a coherent oscillation with the dipolar field, or an enhanced Brownian motion due to an additional contribution to the heating rate from the electric noise. In both scenarios, the sensitivity of an isolated ion and a laser-cooled two-ion crystal has been evaluated and compared. The analysis and understanding of this dynamics is important towards the implementation of a novel Penning-trap mass-spectroscopy technique based on optical detection, aiming at improving precision and sensitivity.

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

“…The PT was designed to allow cooling ions via collisions with gas atoms, but also to implement other cooling mechanisms compatible with ultra-high vacuum, since the pumping barrier between the traps (with a length of 23 mm and a diameter of 2 mm), limits the pressure difference between the PT and the MT. Thus, buffer-gas cooling in the PT restricts those experiments based on creating a two-ion crystal in the MT as envisaged [23]. However, cooling of ions in the PT should be possible by their interaction with a bath of electrons trapped at room temperature in a nested trap [36], or with a cloud of laser-cooled ions.…”

“…The main scientific goal of the TRAPSENSOR Penning-traps facility is to use a single laser-cooled 40 Ca + ion as high-sensitive sensor for precision Penning-trap mass spectrometry [19]. The characterization of a single laser-cooled 40 Ca + ion was accomplished using a Paul trap [22], including the scenario with two ions in the trap [23].…”

“…In the first ever attempt to experimentally realize this concept, the sensitivity of a single 40 Ca + ion laser-cooled to the Doppler limit (T 1 limit mK) has been characterized by studying its axial motion in an open-ring Paul trap [21,22]. The analytical method and a first approach of using just one trap to store the ion of interest and the laser-cooled ion simultaneously has been recently presented [23], following a former idea described in [24]. Such scheme might allow identifying SHEs elements, after thermalization, transport and capture in a Penning trap with open-ring geometry [21], through the fluorescence photons emitted by the 40 Ca + ion.…”

Dynamics of an unbalanced two-ion crystal in a Penning trap for application in optical mass spectrometry

“…[32] for two 40 Ca + ions stored in a linear Paul trap. Moreover, a model to describe the evolution of the fluorescence profile as a function of the excitation frequency, has been developed [15], yielding for the amplitude of the sensor ion in an unbalanced crystal…”

“…The outcomes from the calculations can be combined with the optical response of the sensor ion after applying external fields in resonance with the motional modes of the crystal. The latter has already been studied using a Paul trap with rotational symmetry [14,15]. The proposed method is universal (with respect to the massto-charge ratio), it can be used in broad band mode, and offers a permanent monitoring of the motion of the sensor ion in the trap, allowing for a precise quantification of possible systematic effects arising from trap-electrodes imperfections or misalignments with respect to the magnetic field.…”