48 research outputs found
Rapid Exchange Cooling with Trapped Ions
The trapped-ion quantum charge-coupled device (QCCD) architecture is a
leading candidate for advanced quantum information processing. In current QCCD
implementations, imperfect ion transport and anomalous heating can excite ion
motion during a calculation. To counteract this, intermediate cooling is
necessary to maintain high-fidelity gate performance. Cooling the computational
ions sympathetically with ions of another species, a commonly employed
strategy, creates a significant runtime bottleneck. Here, we demonstrate a
different approach we call exchange cooling. Unlike sympathetic cooling,
exchange cooling does not require trapping two different atomic species. The
protocol introduces a bank of coolant ions which are repeatedly laser
cooled. A computational ion can then be cooled by transporting a coolant ion
into its proximity. We test this concept experimentally with two ions,
executing the necessary transport in 107 , an order of magnitude faster
than typical sympathetic cooling durations. We remove over 96%, and as many as
102(5) quanta, of axial motional energy from the computational ion. We verify
that re-cooling the coolant ion does not decohere the computational ion. This
approach validates the feasibility of a single-species QCCD processor, capable
of fast quantum simulation and computation
Dealing with mobility: Understanding access anytime, anywhere
The rapid and accelerating move towards the adoption and use of mobile technologies has increasingly provided people and organisations with the ability to work away from the office and on the move. The new ways of working afforded by these technologies are often characterised in terms of access to information and people ‘anytime, anywhere’. This paper presents a study of mobile workers that highlights different facets of access to remote people and information, and different facets of anytime, anywhere. Four key factors in mobile work are identified from the study: the role of planning, working in ‘dead time’, accessing remote technological and informational resources, and monitoring the activities of remote colleagues. By reflecting on these issues, we can better understand the role of technology and artefact use in mobile work and identify the opportunities for the development of appropriate technological solutions to support mobile workers
Characterization of Fast Ion Transport via Position-Dependent Optical Deshelving
Ion transport is an essential operation in some models of quantum information
processing, where fast ion shuttling with minimal motional excitation is
necessary for efficient, high-fidelity quantum logic. While fast and cold ion
shuttling has been demonstrated, the dynamics and specific trajectory of an ion
during diabatic transport have not been studied in detail. Here we describe a
position-dependent optical deshelving technique useful for sampling an ion's
position throughout its trajectory, and we demonstrate the technique on fast
linear transport of a ion in a surface-electrode ion trap.
At high speed, the trap's electrode filters strongly distort the transport
potential waveform. With this technique, we observe deviations from the
intended constant-velocity (100 m/s) transport: we measure an average speed of
83(2) m/s and a peak speed of 251(6) m/s over a distance of 120
Abnormal expression of p27kip1 protein in levator ani muscle of aging women with pelvic floor disorders – a relationship to the cellular differentiation and degeneration
BACKGROUND: Pelvic floor disorders affect almost 50% of aging women. An important role in the pelvic floor support belongs to the levator ani muscle. The p27/kip1 (p27) protein, multifunctional cyclin-dependent kinase inhibitor, shows changing expression in differentiating skeletal muscle cells during development, and relatively high levels of p27 RNA were detected in the normal human skeletal muscles. METHODS: Biopsy samples of levator ani muscle were obtained from 22 symptomatic patients with stress urinary incontinence, pelvic organ prolapse, and overlaps (age range 38–74), and nine asymptomatic women (age 31–49). Cryostat sections were investigated for p27 protein expression and type I (slow twitch) and type II (fast twitch) fibers. RESULTS: All fibers exhibited strong plasma membrane (and nuclear) p27 protein expression. cytoplasmic p27 expression was virtually absent in asymptomatic women. In perimenopausal symptomatic patients (ages 38–55), muscle fibers showed hypertrophy and moderate cytoplasmic p27 staining accompanied by diminution of type II fibers. Older symptomatic patients (ages 57–74) showed cytoplasmic p27 overexpression accompanied by shrinking, cytoplasmic vacuolization and fragmentation of muscle cells. The plasma membrane and cytoplasmic p27 expression was not unique to the muscle cells. Under certain circumstances, it was also detected in other cell types (epithelium of ectocervix and luteal cells). CONCLUSIONS: This is the first report on the unusual (plasma membrane and cytoplasmic) expression of p27 protein in normal and abnormal human striated muscle cells in vivo. Our data indicate that pelvic floor disorders are in perimenopausal patients associated with an appearance of moderate cytoplasmic p27 expression, accompanying hypertrophy and transition of type II into type I fibers. The patients in advanced postmenopause show shrinking and fragmentation of muscle fibers associated with strong cytoplasmic p27 expression