Trapping Alkaline Earth Rydberg Atoms Optical Tweezer Arrays.

Neutral atom qubits with Rydberg-mediated interactions are a leading platform for developing large-scale coherent quantum systems. In the majority of experiments to date, the Rydberg states are not trapped by the same potential that confines ground state atoms, resulting in atom loss and constraints on the achievable interaction time. In this Letter, we demonstrate that the Rydberg states of an alkaline earth atom, ytterbium, can be stably trapped by the same red-detuned optical tweezer that also confines the ground state, by leveraging the polarizability of the Yb^{+} ion core. Using the previously unobserved ^{3}S_{1} series, we demonstrate trapped Rydberg atom lifetimes exceeding 100 µs, and observe no evidence of auto- or photoionization from the trap light for these states. We measure a coherence time of T_{2}=59 µs between two Rydberg levels, exceeding the 28 µs lifetime of untrapped Rydberg atoms under the same conditions. These results are promising for extending the interaction time of Rydberg atom arrays for quantum simulation and computing, and are vital to capitalize on the extended Rydberg lifetimes in circular states or cryogenic environments.

Reduced volume and reflection for bright optical tweezers with radial Laguerre-Gauss beams.

Spatially structured light has opened a wide range of opportunities for enhanced imaging as well as optical manipulation and particle confinement. Here, we show that phase-coherent illumination with superpositions of radial Laguerre-Gauss (LG) beams provides improved localization for bright optical tweezer traps, with narrowed radial and axial intensity distributions. Further, the Gouy phase shifts for sums of tightly focused radial LG fields can be exploited for phase-contrast strategies at the wavelength scale. One example developed here is the suppression of interference fringes from reflection near nanodielectric surfaces, with the promise of improved cold-atom delivery and manipulation.

Colourimetric analysis of thermally altered human bone samples.

At this moment, no method is available to objectively estimate the temperature to which skeletal remains have been exposed during a fire. Estimating this temperature can provide crucial information in a legal investigation. Exposure of bone to heat results in observable and measurable changes, including a change in colour. To determine the exposure temperature of experimental bone samples, heat related changes in colour were systemically studied by means of image analysis. In total 1138 samples of fresh human long bone diaphysis and epiphysis, varying in size, were subjected to heat ranging from room temperature to 900 °C for various durations and in different media. The samples were scanned with a calibrated flatbed scanner and photographed with a Digital Single Lens Reflex camera. Red, Green, Blue values and Lightness, A-, and B-coordinates were collected for statistical analysis. Cluster analysis showed that discriminating thresholds for Lightness and B-coordinate could be defined and used to construct a model of decision rules. This model enables the user to differentiate between seven different temperature clusters with relatively high precision and accuracy. The proposed decision model provides an objective, robust and non-destructive method for estimating the exposure temperature of heated bone samples.

Clocked atom delivery to a photonic crystal waveguide.

Experiments and numerical simulations are described that develop quantitative understanding of atomic motion near the surfaces of nanoscopic photonic crystal waveguides (PCWs). Ultracold atoms are delivered from a moving optical lattice into the PCW. Synchronous with the moving lattice, transmission spectra for a guided-mode probe field are recorded as functions of lattice transport time and frequency detuning of the probe beam. By way of measurements such as these, we have been able to validate quantitatively our numerical simulations, which are based upon detailed understanding of atomic trajectories that pass around and through nanoscopic regions of the PCW under the influence of optical and surface forces. The resolution for mapping atomic motion is roughly 50 nm in space and 100 ns in time. By introducing auxiliary guided-mode (GM) fields that provide spatially varying AC Stark shifts, we have, to some degree, begun to control atomic trajectories, such as to enhance the flux into the central vacuum gap of the PCW at predetermined times and with known AC Stark shifts. Applications of these capabilities include enabling high fractional filling of optical trap sites within PCWs, calibration of optical fields within PCWs, and utilization of the time-dependent, optically dense atomic medium for novel nonlinear optical experiments.

Demonstration of quantum entanglement between a single electron spin confined to an InAs quantum dot and a photon.

The electron spin state of a singly charged semiconductor quantum dot has been shown to form a suitable single qubit for quantum computing architectures with fast gate times. A key challenge in realizing a useful quantum dot quantum computing architecture lies in demonstrating the ability to scale the system to many qubits. In this Letter, we report an all optical experimental demonstration of quantum entanglement between a single electron spin confined to a single charged semiconductor quantum dot and the polarization state of a photon spontaneously emitted from the quantum dot's excited state. We obtain a lower bound on the fidelity of entanglement of 0.59±0.04, which is 84% of the maximum achievable given the timing resolution of available single photon detectors. In future applications, such as measurement-based spin-spin entanglement which does not require sub-nanosecond timing resolution, we estimate that this system would enable near ideal performance. The inferred (usable) entanglement generation rate is 3×10(3) s(-1). This spin-photon entanglement is the first step to a scalable quantum dot quantum computing architecture relying on photon (flying) qubits to mediate entanglement between distant nodes of a quantum dot network.

[Extrapulmonary tuberculosis in 3 Dutch patients]. / Extrapulmonale tuberculose bij drie Nederlandse patiënten.

In three patients, two women aged 71 and 59 years and a man aged 49 who had been living in the Netherlands for a long time and who were admitted because of vague symptoms, extrapulmonary manifestations of tuberculosis were diagnosed: tuberculosis of the lumbar spine with psoas abscess, tuberculous peritonitis and adrenal tuberculosis with Addison's disease in a patient with open pulmonary tuberculosis. All three recovered with tuberculostatic therapy (isoniazid, streptomycin, pyrazinamide and rifampicin).

Prognosis of primary anterior shoulder dislocation in young adults.

From 1982 to 1987, 194 patients with 196 primary traumatic anterior shoulder dislocations were treated in our hospital. One hundred and sixty-six patients with 168 shoulder dislocations (87%) were available for study at follow-up an average of 4 years after treatment. The most important prognostic factor in relation to recurrence was the age of the patient at the time of the primary dislocation. The highest recurrence rate was found in patients of 30 years and younger (64%). Athletes in this age group had no worse a prognosis as to recurrence than non-athletes. A fracture of the greater tuberosity improved the prognosis significantly (P less than 0.01). Neither the presence of a Hill-Sachs lesion nor the period of immobilization influenced the recurrence rate in patients aged 30 years and younger.

Identification of sex-linked antigens ofSchistosoma mansoni by immunoelectrophoresis and immunoblotting.

Immunoelectrophoresis and immunoblotting techniques, using sera from hyperimmune rabbits and infected mice, were used to analyze antigens ofSchistosoma mansoni. A comparison was made between the antigenic composition of adult male and female worms, isolated from monosexually and bisexually infected hamsters. A large number of female-specific and a few male-specific antigens were detected. The antigenic composition of females isolated from monosexually infected hamsters was shown to be very different from that of paired females. The presence of a major female-specific antigen with an apparent molecular weight of 32 kd in paired females only, suggests that synthesis of this antigen by female worms is initiated by the male partner. Analysis of the humoral immune response of mice receiving bisexual or monosexual infections showed that both mono- and bisexually infected mice develop a major humoral immune response to a 36-kd polypeptide antigen. A response to a major polypeptide antigen with an apparent molecular weight of 60 kd was observed in bisexually infected mice only. No antibodies reactive with this 60-kd polypeptide are formed during mon-osexual infections with either male or female worms. The 60-kd polypeptide was, however, present in monosexually reared females. This presence, and the presence in bisexually reared males, suggests a transfer of this antigen from females to males.

Modulation of the number of membrane-bound auxin-binding sites during the growth of batch-cultured tobacco cells.

We studied the modulation of the number of membrane-bound naphthaleneacetic acid (NAA)-binding sites during the growth cycle of tobacco cells in batch culture. Both cell number and specific NAA-binding increased exponentially, but at different rates and for different periods. This caused a characteristic modulation of the number of binding sites per cell during the growth cycle: During the first day of the lag phase this number decreased; in the exponential phase it rose markedly, and in the stationary phase it was constant.