Chip-based quantum key distribution Sibson, P; Erven, C; Godfrey, M ...
Nature communications,
02/2017, Letnik:
8, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Improvement in secure transmission of information is an urgent need for governments, corporations and individuals. Quantum key distribution (QKD) promises security based on the laws of physics and ...has rapidly grown from proof-of-concept to robust demonstrations and deployment of commercial systems. Despite these advances, QKD has not been widely adopted, and large-scale deployment will likely require chip-based devices for improved performance, miniaturization and enhanced functionality. Here we report low error rate, GHz clocked QKD operation of an indium phosphide transmitter chip and a silicon oxynitride receiver chip-monolithically integrated devices using components and manufacturing processes from the telecommunications industry. We use the reconfigurability of these devices to demonstrate three prominent QKD protocols-BB84, Coherent One Way and Differential Phase Shift-with performance comparable to state-of-the-art. These devices, when combined with integrated single photon detectors, pave the way for successfully integrating QKD into future telecommunications networks.
Solid-state single spins are promising resources for quantum sensing, quantum-information processing and quantum networks, because they are compatible with scalable quantum-device engineering. ...However, the extension of their coherence times proves challenging. Although enrichment of the spin-zero
C and
Si isotopes drastically reduces spin-bath decoherence in diamond and silicon, the solid-state environment provides deleterious interactions between the electron spin and the remaining spins of its surrounding. Here we demonstrate, contrary to widespread belief, that an impurity-doped (phosphorus) n-type single-crystal diamond realises remarkably long spin-coherence times. Single electron spins show the longest inhomogeneous spin-dephasing time (Formula: see text ms) and Hahn-echo spin-coherence time (T
≈ 2.4 ms) ever observed in room-temperature solid-state systems, leading to the best sensitivities. The extension of coherence times in diamond semiconductor may allow for new applications in quantum technology.
We report the observation and characterization of position-space Bloch oscillations using cold atoms in a tilted optical lattice. While momentum-space Bloch oscillations are a common feature of ...optical lattice experiments, the real-space center-of-mass dynamics are typically unresolvable. In a regime of rapid tunneling and low force, we observe real-space Bloch oscillation amplitudes of hundreds of lattice sites, in both ground and excited bands. We demonstrate two unique capabilities enabled by tracking of Bloch dynamics in position space: measurement of the full position-momentum phase-space evolution during a Bloch cycle, and direct imaging of the lattice band structure. These techniques, along with the ability to exert long-distance coherent control of quantum gases without modulation, may open up new possibilities for quantum control and metrology.
The NV centers in a diamond were successfully created by the femtosecond laser single pulse. We also investigated the effect on the diamond lattice induced by the different laser pulse widths from ...both experimental and theoretical perspectives. Interestingly, in spite of the high thermal conductivity of a diamond, we found that there is a suitable pulse repetition rate of several tens kHz for the formation of NV center ensembles by the femtosecond laser pulse irradiation.
The study of the pearl oyster Pinctada fucata is key to increasing our understanding of the molecular mechanisms involved in pearl biosynthesis and biology of bivalve molluscs. We sequenced ∼1150-Mb ...genome at ∼40-fold coverage using the Roche 454 GS-FLX and Illumina GAIIx sequencers. The sequences were assembled into contigs with N50 = 1.6 kb (total contig assembly reached to 1024 Mb) and scaffolds with N50 = 14.5 kb. The pearl oyster genome is AT-rich, with a GC content of 34%. DNA transposons, retrotransposons, and tandem repeat elements occupied 0.4, 1.5, and 7.9% of the genome, respectively (a total of 9.8%). Version 1.0 of the P. fucata draft genome contains 23 257 complete gene models, 70% of which are supported by the corresponding expressed sequence tags. The genes include those reported to have an association with bio-mineralization. Genes encoding transcription factors and signal transduction molecules are present in numbers comparable with genomes of other metazoans. Genome-wide molecular phylogeny suggests that the lophotrochozoan represents a distinct clade from ecdysozoans. Our draft genome of the pearl oyster thus provides a platform for the identification of selection markers and genes for calcification, knowledge of which will be important in the pearl industry.
Summary
Background A keloid is a specific skin lesion that expands beyond the boundaries of the original injury as it heals. Histologically, it is characterized by the excessive accumulation of ...collagen. However, the reasons for the expansion and the invasive nature of keloids remain unknown.
Objectives We evaluated collagen degradation and migration by cultured keloid fibroblasts based on the assumption that these variables were of functional relevance to the expanding and invasive nature of keloid lesions.
Methods Collagen production was investigated by the detection of type 1 collagen (procollagen type 1C peptide: P1P). Matrix metalloproteinase (MMP)‐1 (interstitial collagenase) and MMP‐2 (gelatinase‐A), were investigated as elements of the collagen degradation system. Enzyme immunoassays were performed to measure the production of P1P, MMP‐1, MMP‐2, and tissue inhibitor of metalloproteinase (TIMP)‐1. To assess the production of MMP‐2 its gelatinolytic activity was measured by zymography using gelatin‐containing gels. The participation of transforming growth factor‐β1 (TGF‐β1) in the production and degradation of collagen was also investigated. Finally, the migratory activity of keloid fibroblasts was evaluated using a colony dispersion assay.
Results The production of type 1 collagen, MMP‐1, MMP‐2, and TIMP‐1 by keloid fibroblasts was 3‐fold, 6‐fold, 2·4‐fold, and 2‐fold greater than that of normal dermal fibroblasts, respectively. Production of P1P was increased when TGF‐β1 was added to cultures of keloid fibroblasts, while it was decreased when anti‐TGF‐β1 antibody was added to the cultures. In contrast, the production of MMP‐1 was decreased by the addition of TGF‐β1 to cultured keloid fibroblasts, while it was increased when anti‐TGF‐β1 antibody was added to the cultures. The production of MMP‐2 increased after treatment with TGF‐β1, but did not change significantly when anti‐TGF‐β1 antibody was added to the cultures. Production of TIMP‐1 did not change significantly when either TGF‐β1 or anti‐TGF‐β1 antibody was added to the cultures. Keloid fibroblasts showed a 2·5‐fold increase of migratory activity compared with normal dermal fibroblasts, while the migratory activity of these fibroblasts was reduced to the control level by treatment with a broad‐spectrum MMP inhibitor (GM 6001).
Conclusions Cultured keloid fibroblasts showed increased production of collagen and MMPs, and TGF‐β1 played a role in this regulation of production. In addition, increased production of MMPs had a role in the high migratory activity of cultured keloid fibroblasts.
Securing information in communication networks is an important challenge in today's world. Quantum Key Distribution (QKD) can provide unique capabilities towards achieving this security, allowing ...intrusions to be detected and information leakage avoided. We report here a record high bit rate prototype QKD system providing a total of 878 Gbit of secure key data over a 34 day period corresponding to a sustained key rate of around 300 kbit/s. The system was deployed over a standard 45 km link of an installed metropolitan telecommunication fibre network in central Tokyo. The prototype QKD system is compact, robust and automatically stabilised, enabling key distribution during diverse weather conditions. The security analysis includes an efficient protocol, finite key size effects and decoy states, with a quantified key failure probability of ε = 10⁻¹⁰.
Neural crest cells (NCC) arise from the dorsal margin of the neural plate border and comprise a unique cell population that migrates to and creates the craniofacial region. Although factors including ...Shh, Fgf8, and bone morphogenetic proteins have been shown to regulate these biological events, the role of parathyroid hormone 1 receptor (Pth1r) has been less studied. We generated an NCC-specific mouse model for Pth1r and researched gene expression, function, and interaction focusing on nasal cartilage framework and midfacial development. Wnt1-Cre;Pth1rfl/fl;Tomatofl/+ mice had perinatal lethality, but we observed short snout and jaws, tongue protrusion, reduced NCC-derived cranial length, increased mineralization in nasal septum and hyoid bones, and less bone mineralization at interfrontal suture in mutants at E18.5. Importantly, the mutant nasal septum and turbinate cartilage histologically revealed gradual, premature accelerated hypertrophic differentiation. We then studied the underlying molecular mechanisms by performing RNA seq analysis and unexpectedly found that expression of Ihh and related signaling molecules was enhanced in mutant nasomaxillary tissues. To see if Pth1r and Ihh signaling are associated, we generated a Wnt1-Cre;
Ihh
fl/fl;
Pth1r
fl/fl;Tomatofl/+ (DKO) mouse and compared the phenotypes to those of each single knockout mouse: Wnt1-Cre;
Ihh
fl/fl;Pth1rfl/+;Tomatofl/+ (Ihh-CKO) and Wnt1-Cre;Ihhfl/+;
Pth1r
fl/fl;Tomatofl/+ (Pth1r-CKO). Ihh-CKO mice displayed a milder effect. Of note, the excessive hypertrophic conversion of the nasal cartilage framework observed in Pth1r-CKO was somewhat rescued DKO embryos. Further, a half cAMP responsive element and the 4 similar sequences containing 2 mismatches were identified from the promoter to the first intron in Ihh gene. Gli1-Cre
ERT2
;Pth1rfl/fl;Tomatofl/+, a Pth1r-deficient model targeted in hedgehog responsive cells, demonstrated the enlarged hypertrophic layer and significantly more Tomato-positive chondrocytes accumulated in the nasal septum and ethmoidal endochondral ossification. Collectively, the data suggest a relevant Pth1r/Ihh interaction. Our findings obtained from novel mouse models for Pth1r signaling illuminate previously unknown aspects in craniofacial biology and development.
Summary
This study investigated the long-term survival and incidence of secondary fractures after fragility hip fractures. The 5-year survival rate was 62%, and the mortality risk was seen in ...patients with GNRI < 92. The 5-year incidence of secondary fracture was 22%, which was significantly higher in patients with a BMI < 20.
Background
Malnutrition negatively influences the postoperative survival of patients with fragility hip fractures (FHFs); however, little is known about their association over the long term.
Objective
This study evaluated the ability of the geriatric nutritional risk index (GNRI) as a risk factor for long-term mortality after FHFs.
Methods
This study included 623 Japanese patients with FHFs over the age of 60 years. We prospectively collected data on admission and during hospitalization and assessed the patients’ conditions after discharge through a questionnaire. We examined the long-term mortality and the incidence of secondary FHFs and assessed the prognostic factors.
Results
The mean observation period was 4.0 years (range 0–7 years). The average age at the time of admission was 82 years (range 60–101 years). The overall survival after FHFs (1 year, 91%; 5 years, 62%) and the incidence of secondary FHFs were high (1 year, 4%; 5 years, 22%). The multivariate Cox proportional hazard analysis revealed the risk factors for mortality as older age (hazard ratio HR 1.04), male sex (HR 1.96), lower GNRI score (HR 0.96), comorbidities (malignancy, HR 2.51; ischemic heart disease, HR 2.24; revised Hasegawa dementia scale ≤ 20, HR 1.64), no use of active vitamin D3 on admission (HR 0.46), and a lower Barthel index (BI) (on admission, HR 1.00; at discharge, HR 0.99). The GNRI scores were divided into four risk categories: major risk (GNRI, < 82), moderate risk (82–91), low risk (92–98), and no risk (> 98). Patients at major and moderate risks of GNRI had a significantly lower overall survival rate (
p
< 0.001). Lower body mass index (BMI) was also identified as a prognostic factor for secondary FHFs (HR 0.88
p
= 0.004).
Conclusions
We showed that older age, male sex, a lower GNRI score, comorbidities, and a lower BI are risk factors for mortality following FHFs. GNRI is a novel and simple predictor of long-term survival after FHFs.
PDF
