6 research outputs found
Mass-selective removal of ions from Paul traps using parametric excitation
We study a method for mass-selective removal of ions from a Paul trap by parametric excitation. This can be achieved by applying an oscillating electric quadrupole field at twice the secular frequency ωsec using pairs of opposing electrodes. While excitation near the resonance with the secular frequency ωsec only leads to a linear increase of the amplitude with excitation duration, parametric excitation near 2ωsec results in an exponential increase of the amplitude. This enables efficient removal of ions from the trap with modest excitation voltages and narrow bandwidth, therefore, substantially reducing the disturbance of ions with other charge-to-mass ratios. We numerically study and compare the mass selectivity of the two methods. In addition, we experimentally show that the barium isotopes with 136 and 137 nucleons can be removed from small ion crystals and ejected out of the trap while keeping 138Ba + ions Doppler cooled, corresponding to a mass selectivity of better than Δ m/ m= 1 / 138. This method can be widely applied to ion trapping experiments without major modifications since it only requires modulating the potential of the ion trap
A subwavelength atomic array switched by a single Rydberg atom
Enhancing light-matter coupling at the level of single quanta is essential
for numerous applications in quantum science. The cooperative optical response
of subwavelength atomic arrays was recently found to open new pathways for such
strong light-matter couplings, while simultaneously offering access to multiple
spatial modes of the light field. Efficient single-mode free-space coupling to
such arrays has been reported, but the spatial control over the modes of
outgoing light fields has remained elusive. Here we demonstrate such spatial
control over the optical response of an atomically thin mirror formed by a
subwavelength array of atoms in free space using a single controlled ancilla
atom excited to a Rydberg state. The switching behavior is controlled by the
admixture of a small Rydberg fraction to the atomic mirror, and consequently
strong dipolar Rydberg interactions with the ancilla. Driving Rabi oscillations
on the ancilla atom, we demonstrate coherent control of the transmission and
reflection of the array. Our results pave the way towards realizing novel
quantum coherent metasurfaces, creating controlled atom-photon entanglement and
deterministic engineering of quantum states of light.Comment: 8 pages, 5 figures + 9 pages Supplementary Informatio
Observation of brane parity order in programmable optical lattices
The Mott-insulating phase of the two-dimensional (2d) Bose-Hubbard model is
expected to be characterized by a non-local brane parity order. Parity order
captures the presence of microscopic particle-hole fluctuations and
entanglement, whose properties depend on the underlying lattice geometry. We
realize 2d Bose-Hubbard models in dynamically tunable lattice geometries, using
neutral atoms in a novel passively phase-stable tunable optical lattice in
combination with programmable site-blocking potentials. We benchmark the
performance of our system by single-particle quantum walks in the square,
triangular, kagome and Lieb lattice. In the strongly correlated regime, we
microscopically characterize the geometry dependence of the quantum
fluctuations and experimentally validate the brane parity as a proxy for the
non-local order parameter signaling the superfluid-to-Mott insulating phase
transition.Comment: Fixed typos and formattin
Optical Trapping of Ion Coulomb Crystals
The electronic and motional degrees of freedom of trapped ions can be controlled and coherently coupled on the level of individual quanta. Assembling complex quantum systems ion by ion while keeping this unique level of control remains a challenging task. For many applications, linear chains of ions in conventional traps are ideally suited to address this problem. However, driven motion due to the magnetic or radio-frequency electric trapping fields sometimes limits the performance in one dimension and severely affects the extension to higher-dimensional systems. Here, we report on the trapping of multiple barium ions in a single-beam optical dipole trap without radio-frequency or additional magnetic fields. We study the persistence of order in ensembles of up to six ions within the optical trap, measure their temperature, and conclude that the ions form a linear chain, commonly called a one-dimensional Coulomb crystal. As a proof-of-concept demonstration, we access the collective motion and perform spectrometry of the normal modes in the optical trap. Our system provides a platform that is free of driven motion and combines advantages of optical trapping, such as state-dependent confinement and nanoscale potentials, with the desirable properties of crystals of trapped ions, such as long-range interactions featuring collective motion. Starting with small numbers of ions, it has been proposed that these properties would allow the experimental study of many-body physics and the onset of structural quantum phase transitions between one- and two-dimensional crystals