15 research outputs found
Surface-electrode ion trap with integrated light source
An atomic ion is trapped at the tip of a single-mode optical fiber in a
cryogenic (8 K) surface-electrode ion trap. The fiber serves as an integrated
source of laser light, which drives the quadrupole qubit transition of
Sr. Through \emph{in situ} translation of the nodal point of the
trapping field, the Gaussian beam profile of the fiber output is imaged, and
the fiber-ion displacement, in units of the mode waist at the ion, is optimized
to within of the mode center despite an initial offset of
. Fiber-induced charging at W is observed to be
V/m at an ion height of m, with charging and discharging
time constants of s and s respectively. This work is of
importance to large-scale, ion-based quantum information processing, where
optics integration in surface-electrode designs may be a crucial enabling
technology.Comment: 4 pages, 4 figure
Finite geometry models of electric field noise from patch potentials in ion traps
We model electric field noise from fluctuating patch potentials on conducting
surfaces by taking into account the finite geometry of the ion trap electrodes
to gain insight into the origin of anomalous heating in ion traps. The scaling
of anomalous heating rates with surface distance, , is obtained for several
generic geometries of relevance to current ion trap designs, ranging from
planar to spheroidal electrodes. The influence of patch size is studied both by
solving Laplace's equation in terms of the appropriate Green's function as well
as through an eigenfunction expansion. Scaling with surface distance is found
to be highly dependent on the choice of geometry and the relative scale between
the spatial extent of the electrode, the ion-electrode distance, and the patch
size. Our model generally supports the dependence currently found by
most experiments and models, but also predicts geometry-driven deviations from
this trend
Laser-induced charging of microfabricated ion traps
Electrical charging of metal surfaces due to photoelectric generation of
carriers is of concern in trapped ion quantum computation systems, due to the
high sensitivity of the ions' motional quantum states to deformation of the
trapping potential. The charging induced by typical laser frequencies involved
in doppler cooling and quantum control is studied here, with microfabricated
surface electrode traps made of aluminum, copper, and gold, operated at 6 K
with a single Sr ion trapped 100 m above the trap surface. The lasers
used are at 370, 405, 460, and 674 nm, and the typical photon flux at the trap
is 10 photons/cm/sec. Charging is detected by monitoring the ion's
micromotion signal, which is related to the number of charges created on the
trap. A wavelength and material dependence of the charging behavior is
observed: lasers at lower wavelengths cause more charging, and aluminum
exhibits more charging than copper or gold. We describe the charging dynamic
based on a rate equation approach.Comment: 8 pages, 8 figure
A microfabricated surface ion trap on a high-finesse optical mirror
A novel approach to optics integration in ion traps is demonstrated based on
a surface electrode ion trap that is microfabricated on top of a dielectric
mirror. Additional optical losses due to fabrication are found to be as low as
80 ppm for light at 422 nm. The integrated mirror is used to demonstrate light
collection from, and imaging of, a single 88 Sr+ ion trapped m
above the mirror.Comment: 4 pages, 3 figure
A surface electrode point Paul trap
We present a model as well as experimental results for a surface electrode
radio-frequency Paul trap that has a circular electrode geometry well-suited
for trapping of single ions and two-dimensional planar ion crystals. The trap
design is compatible with microfabrication and offers a simple method by which
the height of the trapped ions above the surface may be changed \emph{in situ}.
We demonstrate trapping of single and few Sr+ ions over an ion height range of
200-1000 microns for several hours under Doppler laser cooling, and use these
to characterize the trap, finding good agreement with our model.Comment: 10 pages, 11 figures, 1 tabl
Possible Conservation of the K -Quantum Number in Excited Rotating Nuclei
The \ensuremath{\gamma} cascades feeding into low-K and high-K bands in Er are investigated analyzing variances and covariance of the spectrum fluctuations. From a large data set of 1 triple coincidences, \ensuremath{\gamma}-\ensuremath{\gamma} coincidence spectra gated by resolved low-lying rotational bands are analyzed. Low-K bands are found to be fed by a much larger effective number of cascades than high-K bands. The covariance between pairs of gated spectra shows that the cascades feeding low-K bands are different from those feeding the high-K bands. The persistence of the K-selection rules for the excited rotational bands within the angular momentum region 30\ensuremath{\Elzxh}\ensuremath{\le}I\ensuremath{\le}40\ensuremath{\Elzxh} is suggested as explanation
Six Weeks of Low-Load Blood Flow Restricted and High-Load Resistance Exercise Training Produce Similar Increases in Cumulative Myofibrillar Protein Synthesis and Ribosomal Biogenesis in Healthy Males
Purpose: High-load resistance exercise contributes to maintenance of muscle mass, muscle protein quality, and contractile function by stimulation of muscle protein synthesis (MPS), hypertrophy, and strength gains. However, high loading may not be feasible in several clinical populations. Low-load blood flow restricted resistance exercise (BFRRE) may provide an alternative approach. However, the long-term protein synthetic response to BFRRE is unknown and the myocellular adaptations to prolonged BFRRE are not well described.Methods: To investigate this, 34 healthy young subjects were randomized to 6 weeks of low-load BFRRE, HLRE, or non-exercise control (CON). Deuterium oxide (D2O) was orally administered throughout the intervention period. Muscle biopsies from m. vastus lateralis were collected before and after the 6-week intervention period to assess long-term myofibrillar MPS and RNA synthesis as well as muscle fiber-type-specific cross-sectional area (CSA), satellite cell content, and myonuclei content. Muscle biopsies were also collected in the immediate hours following single-bout exercise to assess signaling for muscle protein degradation. Isometric and dynamic quadriceps muscle strength was evaluated before and after the intervention.Results: Myofibrillar MPS was higher in BFRRE (1.34%/day, p < 0.01) and HLRE (1.12%/day, p < 0.05) compared to CON (0.96%/day) with no significant differences between exercise groups. Muscle RNA synthesis was higher in BFRRE (0.65%/day, p < 0.001) and HLRE (0.55%/day, p < 0.01) compared to CON (0.38%/day) and both training groups increased RNA content, indicating ribosomal biogenesis in response to exercise. BFRRE and HLRE both activated muscle degradation signaling. Muscle strength increased 6–10% in BFRRE (p < 0.05) and 13–23% in HLRE (p < 0.01). Dynamic muscle strength increased to a greater extent in HLRE (p < 0.05). No changes in type I and type II muscle fiber-type-specific CSA, satellite cell content, or myonuclei content were observed.Conclusions: These results demonstrate that BFRRE increases long-term muscle protein turnover, ribosomal biogenesis, and muscle strength to a similar degree as HLRE. These findings emphasize the potential application of low-load BFRRE to stimulate muscle protein turnover and increase muscle function in clinical populations where high loading is untenable
Transparent ion trap with integrated photodetector
Fluorescence collection sets the efficiency of state detection and the rate of entanglement generation between remote trapped ion qubits. Despite efforts to improve light collection using various optical elements, solid angle capture is limited to ≈10% for implementations that are scalable to many ions. We present an approach based on fluorescence detection through a transparent trap using an integrated photodetector, combining collection efficiency approaching 50% with scalability. We microfabricate transparent surface traps with indium tin oxide and verify stable trapping of single ions. The fluorescence from a cloud of ions is detected using a photodiode sandwiched with a transparent trap.United States. Intelligence Advanced Research Projects ActivityMIT-Harvard Center for Ultracold Atom