Sub-micron positioning of trapped ions with respect to the absolute center of a standing-wave cavity field

Abstract

We demonstrate that it is possible, with sub-micron precision, to locate the absolute center of a Fabry-Pérot resonator oriented along the rf-field-free axis of a linear Paul trap through the application of two simultaneously resonating optical fields. In particular, we apply a probe field, which is near-resonant with an electronic transition of trapped ions, simultaneously with an offresonant strong field acting as a periodic AC Stark-shifting potential. Through the resulting spatially modulated fluorescence signal we can find the cavity center of an 11.7 mm-long symmetric FabryPérot cavity with a precision of ±135 nm, which is smaller than the periodicity of the individual standing wave fields. This can e.g. be used to position the minimum of the axial trap potential with respect to the center of the cavity at any location along the cavity mode.

Visibility of Young’s Interference Fringes: Scattered Light from Small Ion Crystals

“…The method could pave the way towards temperature measurements of ion crystals at low trap frequencies where standard sideband methods, highly successful in tightly confining potentials [20], become increasingly hard. We also see applications when the trap potential is adiabatically lowered [24], e.g., when ions are loaded into optical potentials [25][26][27]. The experiment also provides opportunities to investigate multi-ion entanglement [28][29][30][31][32][33] or measurements of photon-photon correlations and their back action on the ion crystals [34][35][36].…”

Quantum duets working as autonomous thermal motors

“…The quantum regime considered here should potentially be realizable with two sideband laser-cooled atomic ions commonly confined by a harmonic potential, while individually interacting with each their periodic dipole-induced potential with variable spatial phase relation [27][28][29][30][31]. The individual temperatures of the two ions can be controlled F .…”

“…Confinement of the ions by a common harmonic trap potential will lead to an effective harmonic binding force between them [26], while spatially periodical potentials along the axis defined by the two ions can be realized through off-resonant electrical dipole forces induced by standing wave light fields [27][28][29][30]. By either choosing two identical ion species initialized in different internal states or two different ion isotopes, different polarization states and/or longitudinal modes of an Fabry-Perot cavity could enable particle dependent periodical potentials with a constant, but tunable phase relation between them [31].…”

Localization of ions within one-, two- and three-dimensional Coulomb crystals by a standing wave optical potential

“…of the trap. Ions were previously positioned at the absolute center of the optical cavity following the method of [46]. After switching off the cooling and optical pumping fields, a σ − -circularly polarized standing wave field detuned either to the blue or the red side of the D 3/2 → P 1/2 transition by ±0.76 THz is ramped up adiabatically for 2 µs and held at its maximum level for 1 µs.…”