Entanglement of nanophotonic quantum memory nodes in a telecom network.

A key challenge in realizing practical quantum networks for long-distance quantum communication involves robust entanglement between quantum memory nodes connected by fibre optical infrastructure1-3. Here we demonstrate a two-node quantum network composed of multi-qubit registers based on silicon-vacancy (SiV) centres in nanophotonic diamond cavities integrated with a telecommunication fibre network. Remote entanglement is generated by the cavity-enhanced interactions between the electron spin qubits of the SiVs and optical photons. Serial, heralded spin-photon entangling gate operations with time-bin qubits are used for robust entanglement of separated nodes. Long-lived nuclear spin qubits are used to provide second-long entanglement storage and integrated error detection. By integrating efficient bidirectional quantum frequency conversion of photonic communication qubits to telecommunication frequencies (1,350 nm), we demonstrate the entanglement of two nuclear spin memories through 40 km spools of low-loss fibre and a 35-km long fibre loop deployed in the Boston area urban environment, representing an enabling step towards practical quantum repeaters and large-scale quantum networks.

The fast multi-frame X-ray diffraction detector at the Dynamic Compression Sector.

A multi-frame, X-ray diffraction (XRD) detector system has been developed for use in time-resolved XRD measurements during single-event experiments at the Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS). The system is capable of collecting four sequential XRD patterns separated by 153 ns, the period of the APS storage ring in the 24-bunch mode. This capability allows an examination of the temporal evolution of material dynamics in single-event experiments, such as plate impact experiments, explosive detonations, and split-Hopkinson pressure bar experiments. This system is available for all user experiments at the DCS. Here, the system description and measured performance parameters (detective quantum efficiency, spatial and temporal resolution, and dynamic range) are presented along with procedures for synchronization and image post-processing.

Detonation synthesis of carbon nano-onions via liquid carbon condensation.

Transit through the carbon liquid phase has significant consequences for the subsequent formation of solid nanocarbon detonation products. We report dynamic measurements of liquid carbon condensation and solidification into nano-onions over ∽200 ns by analysis of time-resolved, small-angle X-ray scattering data acquired during detonation of a hydrogen-free explosive, DNTF (3,4-bis(3-nitrofurazan-4-yl)furoxan). Further, thermochemical modeling predicts a direct liquid to solid graphite phase transition for DNTF products ~200 ns post-detonation. Solid detonation products were collected and characterized by high-resolution electron microscopy to confirm the abundance of carbon nano-onions with an average diameter of ∽10 nm, matching the dynamic measurements. We analyze other carbon-rich explosives by similar methods to systematically explore different regions of the carbon phase diagram traversed during detonation. Our results suggest a potential pathway to the efficient production of carbon nano-onions, while offering insight into the phase transformation kinetics of liquid carbon under extreme pressures and temperatures.

Entanglement between more than two hundred macroscopic atomic ensembles in a solid.

There are both fundamental and practical motivations for studying whether quantum entanglement can exist in macroscopic systems. However, multiparty entanglement is generally fragile and difficult to quantify. Dicke states are multiparty entangled states where a single excitation is delocalized over many systems. Building on previous work on quantum memories for photons, we create a Dicke state in a solid by storing a single photon in a crystal that contains many large atomic ensembles with distinct resonance frequencies. The photon is re-emitted at a well-defined time due to an interference effect analogous to multi-slit diffraction. We derive a lower bound for the number of entangled ensembles based on the contrast of the interference and the single-photon character of the input, and we experimentally demonstrate entanglement between over two hundred ensembles, each containing a billion atoms. We also illustrate the fact that each individual ensemble contains further entanglement.Multipartite entanglement is of both fundamental and practical interest, but is notoriously difficult to witness and characterise. Here, Zarkeshian et al. demonstrate multipartite entanglement in an atomic frequency comb storing a single photon in a Dicke state spread over a macroscopic ensemble.

Properties of a Rare-Earth-Ion-Doped Waveguide at Sub-Kelvin Temperatures for Quantum Signal Processing.

We characterize the 795 nm ^{3}H_{6} to ^{3}H_{4} transition of Tm^{3+} in a Ti^{4+}:LiNbO_{3} waveguide at temperatures as low as 800 mK. Coherence and hyperfine population lifetimes-up to 117 µs and 2.5 h, respectively-exceed those at 3 K at least tenfold, and are equivalent to those observed in a bulk Tm^{3+}:LiNbO_{3} crystal under similar conditions. We also find a transition dipole moment that is equivalent to that of the bulk. Finally, we prepare a 0.5 GHz-bandwidth atomic frequency comb of finesse >2 on a vanishing background. These results demonstrate the suitability of rare-earth-ion-doped waveguides created using industry-standard Ti indiffusion in LiNbO_{3} for on-chip quantum applications.

Proposal and proof-of-principle demonstration of non-destructive detection of photonic qubits using a Tm:LiNbO3 waveguide.

Non-destructive detection of photonic qubits is an enabling technology for quantum information processing and quantum communication. For practical applications, such as quantum repeaters and networks, it is desirable to implement such detection in a way that allows some form of multiplexing as well as easy integration with other components such as solid-state quantum memories. Here, we propose an approach to non-destructive photonic qubit detection that promises to have all the mentioned features. Mediated by an impurity-doped crystal, a signal photon in an arbitrary time-bin qubit state modulates the phase of an intense probe pulse that is stored during the interaction. Using a thulium-doped waveguide in LiNbO3, we perform a proof-of-principle experiment with macroscopic signal pulses, demonstrating the expected cross-phase modulation as well as the ability to preserve the coherence between temporal modes. Our findings open the path to a new key component of quantum photonics based on rare-earth-ion-doped crystals.

Real-Time Examination of Atomistic Mechanisms during Shock-Induced Structural Transformation in Silicon.

The experimental determination of atomistic mechanisms linking crystal structures during a compression-driven solid-solid phase transformation is a long-standing and challenging scientific objective. Using new capabilities at the Dynamic Compression Sector at the Advanced Photon Source, the structure of shocked Si at 19 GPa was identified as simple hexagonal, and the lattice orientations between ambient cubic diamond and simple hexagonal structures were related. The approach is general and provides a powerful new method for examining atomistic mechanisms during stress-induced structural changes.

Tm 3+ Tm 3+ : Y3Ga5O12 materials for spectrally multiplexed quantum memories.

We investigate the relevant spectroscopic properties of the 795 nm (3)H(6)↔(3)H(4) transition in 1% Tm(3+):Y(3)Ga(5)O(12) at temperatures as low as 1.2 K for optical quantum memories based on persistent spectral tailoring of narrow absorption features. Our measurements reveal that this transition has uniform coherence properties over a 56 GHz bandwidth, and a simple hyperfine structure split by ± 44 MHz/T with lifetimes of up to hours. Furthermore, we find a (3)F(4) population lifetime of 64 ms-one of the longest lifetimes observed for an electronic level in a solid--and an exceptionally long coherence lifetime of 490 µs--the longest ever observed for optical transitions of Tm(3+) ions in a crystal. Our results suggest that this material allows realizing broadband quantum memories that enable spectrally multiplexed quantum repeaters.

A Rare and Unusual Case of Burkitt's Lymphoma Presenting with a Prostate Mass in a 12-Year-Old Boy.

Burkitt's lymphoma is the most frequent subtype of non-Hodgkin's lymphoma in childhood. Radiographic findings are protean and can often overlap with other neoplastic and nonneoplastic processes. We present an unusual case of Burkitt's lymphoma in a 12-year-old boy presenting with a one-week history of urinary retention, dysuria, and "tailbone pain," as well as a 4-week history of jaw pain, initially treated as a dental abscess. On dental radiography, the patient was found to have resorption of alveolar bone adjacent to the lower first molars bilaterally, in keeping with "floating teeth," classically associated with Langerhans cell histiocytosis. Additionally, a large, eccentric, prostatic mass was noted, prompting the inclusion of rhabdomyosarcoma on the differential diagnosis, with subsequent definitive diagnosis of Burkitt's lymphoma on tissue and bone marrow biopsy. This case highlights the imaging overlap of these childhood neoplasms with an unusual lymphomatous prostate mass. It is important that the radiologists and pediatricians be aware of this potential overlap and the unusual presentation of Burkitt's lymphoma.

Limitations in the rapid extraction of evoked potentials using parametric modeling.

The rapid extraction of variations in evoked potentials (EPs) is of great clinical importance. Parametric modeling using autoregression with an exogenous input (ARX) and robust evoked potential estimator (REPE) are commonly used methods for extracting EPs over the conventional moving time average. However, a systematic study of the efficacy of these methods, using known synthetic EPs, has not been performed. Therefore, the current study evaluates the restrictions of these methods in the presence of known and systematic variations in EP component latency and signal-to-noise ratios (SNR). In the context of rapid extraction, variations of wave V of the auditory brainstem in response to stimulus intensity were considered. While the REPE methods were better able to recover the simulated model of the EP, morphology and the latency of the ARX-estimated EPs was a closer match to the actual EP than than that of the REPE-estimated EPs. We, therefore, concluded that ARX rapid extraction would perform better with regards to the rapid tracking of latency variations. By tracking simulated and empirically induced latency variations, we conclude that rapid EP extraction using ARX modeling is only capable of extracting latency variations of an EP in relatively high SNRs and, therefore, should be used with caution in low-noise environments. In particular, it is not a suitable method for the rapid extraction of early EP components such as the auditory brainstem potential.

Melanocytic naevi and basal cell carcinoma: is there an association?

BACKGROUND: Melanoma and basal cell carcinoma (BCC) affect similar body sites and share a complex relationship with sun exposure. OBJECTIVE: To establish the existence and magnitude of association between melanocytic naevi, the strongest predictors of melanoma, and BCC to give possible insights into shared pathways of solar ultraviolet tumourigenesis. METHODS: In a community-based longitudinal Australian study, detailed information was collected about sun sensitivity, and dermatologists assessed skin colour and counted naevi on the forearms (1986) and back (1992). The BCC frequency and sites were prospectively monitored until 2007. Multivariate logistic regression was used to assess the association of naevi on the forearms or on the back with the development of BCC, adjusting for other risk factors. RESULTS: Of 1621 study participants in 1992, 1339 (average age 49) had complete follow-up and 401 (30%) of these had 1202 histologically confirmed BCCs until 2007. After adjustment for age, gender, skin colour, naevi on the back and sun exposure, overall BCC risk increased significantly in those with forearm naevi (odds ratio: 1.5; 95% confidence intervals: 1.1-1.9). Risk of BCC specifically on the back was doubled in those with many (11 or more) forearm naevi compared with no forearm naevi (odds ratio: 2.4; 95% confidence interval: 1.1-4.8). Naevi on the back were not associated with subsequent basal cell carcinoma. CONCLUSIONS: High naevus prevalence on the arms is associated with future BCC development.

Long-term efficacy of 2-0 Prolene brow suspensions for congenital ptosis.

AIMS: To highlight the long-lasting benefit of 2-0 Prolene brow suspension for congenital ptosis. METHODS: Retrospective case review of 38 paediatric cases at two centres in the United Kingdom. RESULTS: Six cases continue to have a successful functional and cosmetic result ranging from 6 to 10 years. CONCLUSIONS: Brow suspension with 2-0 Prolene can be long-lasting in some patients.

Tripartite entanglement versus tripartite nonlocality in three-qubit Greenberger-Horne-Zeilinger-class states.

We analyze the relationship between tripartite entanglement and genuine tripartite nonlocality for three-qubit pure states in the Greenberger-Horne-Zeilinger class. We consider a family of states known as the generalized Greenberger-Horne-Zeilinger states and derive an analytical expression relating the three-tangle, which quantifies tripartite entanglement, to the Svetlichny inequality, which is a Bell-type inequality that is violated only when all three qubits are nonlocally correlated. We show that states with three-tangle less than 1/2 do not violate the Svetlichny inequality. On the other hand, a set of states known as the maximal slice states does violate the Svetlichny inequality, and exactly analogous to the two-qubit case, the amount of violation is directly related to the degree of tripartite entanglement. We discuss further interesting properties of the generalized Greenberger-Horne-Zeilinger and maximal slice states.

The post-infarction nurse practitioner project: A prospective study comparing nurse intervention with conventional care in a non-high-risk myocardial infarction population.

OBJECTIVES: To confirm the feasibility of nurse practitioner interventionin non-high-risk patients with recent myocardial infarction (MI). DESIGN: Observational study. SETTING: Acute coronary care unit in a teaching hospital. METHODS: We performed an open-label feasibility study to identify non-high-risk MI patients and evaluate the outcome of a new nurse practitioner intervention programme. The initial pilot phase served to identify the non-high-risk population. In the subsequent confirmation phase, 500 consecutive non-high-risk post-MI patients with preserved LV function without heart failure were included to receive nurse practitioner management. The nurse practitioner intervention started on transfer from the coronary care unit to the cardiology ward and continued thereafter for up to 30 days. MAIN OUTCOME MEASURES: Time to first event analysis of death from all causes or repeat myocardial infarction. RESULTS: 500 Patients without signs of heart failure or depressed LV function were identified as nonhigh- risk and eligible for inclusion in the nurse practitioner intervention programme. In the implementation phase, none of the patients died and 0.9% developed a repeat myocardial infarction after 30 days of follow-up. Compared with the pilot phase, patients in the implementation phase spent fewer days in hospital (mean 11.1 versus 6.2 days; p<0.001). CONCLUSION: It is feasible to identify non-high-risk post-MI patients, who can be managed adequately by a nurse practitioner. Embedding experienced nurse practitioners within critical care pathways may result in significant decreases in length of hospital stay. (Neth Heart J 2009;17:61-7.Neth Heart J 2009;17:61-7.).

Visual perception during phacoemulsification cataract surgery under subtenons anaesthesia.

AIM: The aim of this study was to record the subjective visual experience of patients during phacoemulsification and intraocular lens implantation under subtenons anaesthesia. METHODS: Prospective, nonrandomised, cohort, postoperative questionnaire based study. Patients selected underwent routine phacoemulsification and intraocular lens implantation under regional subtenons anaesthesia. chi(2) and Fisher's exact tests (two-tail) were used to evaluate the data. RESULTS: A total of 104 patients were selected, 38 (36.5%) were male and 66 (63.5%) were female. The mean age of patients was 74.0+/-8.8 years. In all, 87.5% saw light during the operation with 9.6% finding this painful. Photophobia was highest among younger patients (P=0.002). Coloured lights were seen by 56.7% and 13.5% found the visual experience frightening. Frightening visual experiences were significantly associated with the perception of colour (P=0.005) and photophobia (P=0.003). A volume of anaesthetic greater than 4 m was associated with a significant reduction in anxiety as a result of the visual experience (P=0.003). None of the other visual phenomena recorded were associated with a frightening visual experience. CONCLUSIONS: Patients undergoing regional anaesthesia experience a wide variety of visual sensations during cataract surgery. Perception of colour and volumes of anaesthetic less than 4 m appear to be associated with the visual experience being more frightening. Detailed preoperative counselling is mandatory. It should include comprehensive information about visual perception during the procedure relieving the patients from unnecessary distress.

Fc-signalling in the modulation of immune responses by passive antibody.

Passive antibody can both suppress and augment immune responses. Until recently, there was virtual unanimity on the importance of the interaction of the Fc portion of modulating antibody with Fc-receptors (Fc-signalling), especially in experiments involving the suppression by antibody. Experiments reported in the last few years, that do not demonstrate the range of Fc-portion/Fc-receptor influences on the suppression of immune responses by passive antibody, have introduced new uncertainty into this field. The purpose of this paper is to review how the initial controversy on the influence of Fc-signalling in inhibition by passive antibody was resolved. Old and new approaches are suggested that may help in resolving the current uncertainty engendered by recent experimental results that were interpreted to mean that passive suppressive antibody does not utilize the inhibitory FcgammaRIIB receptor. An understanding of the factors that influence negative Fc-signalling is needed in order to optimize clinical therapies whose action depends on the suppressive property of antibody.