38 research outputs found
Cavity sideband cooling of a single trapped ion
We report a demonstration and quantitative characterization of
one-dimensional cavity cooling of a single trapped 88Sr+ ion in the resolved
sideband regime. We measure the spectrum of cavity transitions, the rates of
cavity heating and cooling, and the steady-state cooling limit. The cavity
cooling dynamics and cooling limit of 22.5(3) motional quanta, limited by the
moderate coupling between the ion and the cavity, are consistent with a simple
model [Phys. Rev. A 64, 033405] without any free parameters, validating the
rate equation model for cavity cooling.Comment: 5 pages, 4 figure
Electron impact ionization loading of a surface electrode ion trap
We demonstrate a method for loading surface electrode ion traps by electron
impact ionization. The method relies on the property of surface electrode
geometries that the trap depth can be increased at the cost of more
micromotion. By introducing a buffer gas, we can counteract the rf heating
assocated with the micromotion and benefit from the larger trap depth. After an
initial loading of the trap, standard compensation techniques can be used to
cancel the stray fields resulting from charged dielectric and allow for the
loading of the trap at ultra-high vacuum.Comment: 4 pages, 5 eps figures. Shift in focus, minor correction
Suppression of Heating Rates in Cryogenic Surface-Electrode Ion Traps
Dense arrays of trapped ions provide one way of scaling up ion trap quantum
information processing. However, miniaturization of ion traps is currently
limited by sharply increasing motional state decoherence at sub-100 um
ion-electrode distances. We characterize heating rates in cryogenically cooled
surface-electrode traps, with characteristic sizes in 75 um to 150 um range.
Upon cooling to 6 K, the measured rates are suppressed by 7 orders of
magnitude, two orders of magnitude below previously published data of similarly
sized traps operated at room temperature. The observed noise depends strongly
on fabrication process, which suggests further improvements are possible.Comment: 4 pages, 4 figure
Superconducting microfabricated ion traps
We fabricate superconducting ion traps with niobium and niobium nitride and
trap single 88Sr ions at cryogenic temperatures. The superconducting transition
is verified and characterized by measuring the resistance and critical current
using a 4-wire measurement on the trap structure, and observing change in the
rf reflection. The lowest observed heating rate is 2.1(3) quanta/sec at 800 kHz
at 6 K and shows no significant change across the superconducting transition,
suggesting that anomalous heating is primarily caused by noise sources on the
surface. This demonstration of superconducting ion traps opens up possibilities
for integrating trapped ions and molecular ions with superconducting devices.Comment: 3 pages, 2 figure
The Kondo Effect in the Presence of Magnetic Impurities
We measure transport through gold grain quantum dots fabricated using
electromigration, with magnetic impurities in the leads. A Kondo interaction is
observed between dot and leads, but the presence of magnetic impurities results
in a gate-dependent zero-bias conductance peak that is split due to an RKKY
interaction between the spin of the dot and the static spins of the impurities.
A magnetic field restores the single Kondo peak in the case of an
antiferromagnetic RKKY interaction. This system provides a new platform to
study Kondo and RKKY interactions in metals at the level of a single spin.Comment: 5 pages, 4 figure
Cryogenic Ion Trapping Systems with Surface-Electrode Traps
We present two simple cryogenic RF ion trap systems in which cryogenic
temperatures and ultra high vacuum pressures can be reached in as little as 12
hours. The ion traps are operated either in a liquid helium bath cryostat or in
a low vibration closed cycle cryostat. The fast turn around time and
availability of buffer gas cooling made the systems ideal for testing
surface-electrode ion traps. The vibration amplitude of the closed cycled
cryostat was found to be below 106 nm. We evaluated the systems by loading
surface-electrode ion traps with Sr ions using laser ablation, which
is compatible with the cryogenic environment. Using Doppler cooling we observed
small ion crystals in which optically resolved ions have a trapped lifetime
over 2500 minutes.Comment: 10 pages, 13 EPS figure
Laser ablation loading of a surface-electrode ion trap
We demonstrate loading by laser ablation of Sr ions into a
mm-scale surface-electrode ion trap. The laser used for ablation is a pulsed,
frequency-tripled Nd:YAG with pulse energies of 1-10 mJ and durations of 3-5
ns. An additional laser is not required to photoionize the ablated material.
The efficiency and lifetime of several candidate materials for the laser
ablation target are characterized by measuring the trapped ion fluorescence
signal for a number of consecutive loads. Additionally, laser ablation is used
to load traps with a trap depth (40 meV) below where electron impact ionization
loading is typically successful ( 500 meV).Comment: 4 pages, 4 figure
Time-separated entangled light pulses from a single-atom emitter
The controlled interaction between a single, trapped, laser-driven atom and
the mode of a high-finesse optical cavity allows for the generation of
temporally separated, entangled light pulses. Entanglement between the
photon-number fluctuations of the pulses is created and mediated via the atomic
center-of-mass motion, which is interfaced with light through the mechanical
effect of atom-photon interaction. By means of a quantum noise analysis we
determine the correlation matrix which characterizes the entanglement, as a
function of the system parameters. The scheme is feasible in experimentally
accessible parameter regimes. It may be easily extended to the generation of
entangled pulses at different frequencies, even at vastly different
wavelengths.Comment: 17 pages, 5 figures. Modified version, to appear in the New Journal
of Physic
Ultrasensitive force and displacement detection using trapped ions
The ability to detect extremely small forces is vital for a variety of
disciplines including precision spin-resonance imaging, microscopy, and tests
of fundamental physical phenomena. Current force-detection sensitivity limits
have surpassed 1 (atto ) through coupling of micro or
nanofabricated mechanical resonators to a variety of physical systems including
single-electron transistors, superconducting microwave cavities, and individual
spins. These experiments have allowed for probing studies of a variety of
phenomena, but sensitivity requirements are ever-increasing as new regimes of
physical interactions are considered. Here we show that trapped atomic ions are
exquisitely sensitive force detectors, with a measured sensitivity more than
three orders of magnitude better than existing reports. We demonstrate
detection of forces as small as 174 (yocto ), with a
sensitivity 390 using crystals of Be
ions in a Penning trap. Our technique is based on the excitation of normal
motional modes in an ion trap by externally applied electric fields, detection
via and phase-coherent Doppler velocimetry, which allows for the discrimination
of ion motion with amplitudes on the scale of nanometers. These experimental
results and extracted force-detection sensitivities in the single-ion limit
validate proposals suggesting that trapped atomic ions are capable of detecting
of forces with sensitivity approaching 1 . We anticipate that
this demonstration will be strongly motivational for the development of a new
class of deployable trapped-ion-based sensors, and will permit scientists to
access new regimes in materials science.Comment: Expanded introduction and analysis. Methods section added. Subject to
press embarg
Demonstration of a Scalable, Multiplexed Ion Trap for Quantum Information Processing
Author's final manuscript: July 9, 2009A scalable, multiplexed ion trap for quantum information processing is fabricated and tested. The trap design and fabrication process are optimized for scalability to small trap size and large numbers of interconnected traps, and for integration of control electronics and optics. Multiple traps with similar designs are tested with [superscript 111]Cd[superscript +], [superscript 25]Mg[superscript +], and [superscript 88]Sr[superscript +] ions at room temperature and with [superscript 88]Sr[superscript +] at 6 K, with respective ion lifetimes of 90 s, 300 ± 30 s, 56 ± 6 s, and 4.5 ± 1.1 hours. The motional heating rate for [superscript 25]Mg[superscript +] at room temperature and a trap frequency of 1.6 MHz is measured to be 7 ± 3 quanta per millisecond. For [superscript 88]Sr[superscript +] at 6 K and 540 kHz the heating rate is measured to be 220 ± 30 quanta per second.United States. Intelligence Advanced Research Projects ActivityNational Institute of Standards and Technology (U.S.) (Quantum Information Program