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Multipartite entanglement is a critical resource in quantum information processing that exhibits much richer phenomenon and stronger correlations than in bipartite systems. This advantage is also reflected in its multi-user applications. Although many demonstrations have used photonic polarization qubits, polarization-mode dispersion confines the transmission of photonic polarization qubits through an optical fiber. Consequently, time-bin qubits have a particularly important role to play in quantum communication systems. Here, we generate a three-photon time-bin Greenberger-Horne-Zeilinger (GHZ) state using a 2 x 2 optical switch as a time-dependent beam splitter to entangle time-bin Bell states from a spontaneous parametric down-conversion source and a weak coherent pulse. To characterize the three-photon time-bin GHZ state, we performed measurement estimation, showed a violation of the Mermin inequality, and used quantum state tomography to fully reconstruct a density matrix, which shows a state fidelity exceeding 70%. We expect that our three-photon time-bin GHZ state can be used for long-distance multi-user quantum communication., Comment: 8 pages, 4 figures, 1 table

This study aims to establish a fracture prediction method that considers the effect of crack opening modes to accurately predict brittle fracture occurring at the beam-to-column joints of building structures. Beam-to-diaphragm joint models were tested under cyclic loading, designed to connect building structures. Finite element analysis and failure prediction using the Weibull stress approach were conducted. Using mixed-mode ratio, the effect of crack opening modes on prediction accuracy was examined. Further, the accuracy of fracture prediction were improved through corrections for different modes.

Background The data of sequential therapy of anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) in clinical practice have been limited. Methods We reviewed the clinical data of patients with ALK-rearranged non-small cell lung cancer who received crizotinib (CRZ) or alectinib (ALEC) between May 2012 and December 2016. Patients were divided into two groups based on the first-administered ALK-TKI, the CRZ or ALEC group. The combined time-to-treatment failure (TTF) was defined as the sum of the ‘TTF of CRZ’ plus the ‘TTF of ALEC’ if patients were treated with CRZ followed by ALEC in the CRZ group. The primary end-point is the comparison between the combined TTF and the TTF of ALEC in the ALEC group. Results Of 864 patients enrolled from 61 institutions, 840 patients were analysed. There were 535 of 305 patients in the CRZ/ALEC groups. The combined TTF in the CRZ group was significantly longer than TTF in the ALEC group (median, 34.4 versus 27.2 months; hazard ratio [HR], 0.709; P = 0.0044). However, there was no significant difference in overall survival (OS) between the patients who received ALEC after CRZ in the CRZ group and the patients in the ALEC group (median, 88.4 months versus. not reached; HR, 1.048; P = 0.7770). In the whole population, the CRZ group had a significantly shorter OS than the ALEC group (median, 53.6 months versus not reached; HR, 1.821, P Conclusion The combined TTF in the CRZ group was significantly longer than the TTF in the ALEC group; however, OS benefit of sequential therapy against ALEC as the first ALK-TKI was not shown.

One-photon and two-photon interferences have recently led researchers to develop new classes of quantum cryptographic protocols.

Quantum key distribution (QKD) offers a reliable solution to communication problems that require long-term data security. For its widespread use, however, the rate and reach of QKD systems must be improved. Twin-field (TF) QKD is a step forward toward this direction, with early demonstrations suggesting it can beat the current rate-versus-distance records. A recently introduced variant of TF-QKD is particularly suited for experimental implementation, and has been shown to offer a higher key rate than other variants in the asymptotic regime where users exchange an infinite number of signals. Here, we extend the security of this protocol to the finite-key regime, showing that it can overcome the fundamental bounds on point-to-point QKD with around $10^{10}$ transmitted signals. Within distance regimes of interest, our analysis offers higher key rates than those of alternative variants. Moreover, some of the techniques we develop are applicable to the finite-key analysis of other QKD protocols., 26 pages, 5 figures. v2: major changes on subsection "Concentration inequality for sums of dependent random variables", minor changes elsewhere. v3: Changes on subsection "Concentration inequality for sums of dependent random variables", to use the newest version of the inequality in Ref. [38]. Minor changes in citations elsewhere. v4: Fixed wrong citation numbers in graph legends

Compared with entanglement with multiple types of noise, entanglement including only one type of error is a favorable fundamental resource not only for quantum communication but also for distributed quantum computation. We consider protocol that presents single-error-type entanglement for distant qubits via coherent-state transmission over a lossy channel. This protocol is regarded as a subroutine to serve entanglement for larger protocol to yield a final output, such as ebits or pbits. In this paper, we provide a subroutine protocol which achieves the global optimal for typical jointly convex yield functions monotonically non-decreasing with respect to the singlet fraction, such as an arbitrary convex function of a singlet fraction and two-way distillable entanglement/key. Entanglement generation based on remote non-destructive parity measurement protocol [K. Azuma, H. Takeda, M. Koashi, and N. Imoto, Phys. Rev. A 85, 062309 (2012)] is identified as such an optimal subroutine., 12 pages, 6 figures

The private capacity of a lossy bosonic channel shows that there remains not much room to improve known point-to-point quantum key distribution (QKD) protocols further, in terms of the key rate versus distance. The current question in our field is how to overcome this fundamental limit with the help of a single station in the middle between communicators. In this talk, we explore recent trials to achieve this goal, such as adaptive measurement-device-independent QKD and twin-field QKD. These trials are good milestones towards the realization of quantum repeater networks.

Background Pulmonary alveolar proteinosis (PAP) is a diffuse lung disease characterized by the abnormal accumulation of surfactant-like material within the alveolar spaces and distal bronchioles. If high-resolution computed tomography (HRCT) indicates the presence of PAP, a definitive diagnosis of PAP is established when consistent pathological findings are obtained. Herein, we retrospectively studied the yield and safety of bronchofiberscopy in the diagnosis of PAP. Methods One hundred and fifty consecutive patients with PAP were prospectively registered in the PAP cohort database of the National Hospital Organization Kinki-Chuo Chest Medical Center between January 1991 and December 2018. We examined 86 patients who underwent bronchofiberscopy with bronchoalveolar lavage (BAL) and transbronchial lung forceps biopsy (TBLB). Results The patients included 56 men and 30 women, with a median age of 57 years. All patients had autoimmune PAP, and the median level of anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies was 42.8 μg/mL. The diagnostic yield was 90.7% (78/86) with BAL and 81.4% (70/86) with TBLB. The combination of BAL and TBLB increased the yield to 98.8%. Age, disease severity score, and frequency of traction bronchiectasis on HRCT were significantly different between the TBLB-positive and TBLB-negative groups. No patient developed serious complications due to bronchofiberscopy; TBLB-related complications included pneumothorax (3.5%) and minimal bleeding (7.0%). Conclusions Bronchofiberscopy, in combination with BAL and TBLB, is an effective and safe method for the diagnosis of PAP, with a yield of 98.8%.

Quantum networks will enable the implementation of communication tasks with qualitative advantages with respect to the communication networks known today. While it is expected that the first demonstrations of small scale quantum networks will take place in the near term, many challenges remain to scale them. To compare different solutions, optimize over parameter space, and inform experiments, it is necessary to evaluate the performance of concrete quantum network scenarios. Here, the authors review the state-of-the-art of tools for evaluating the performance of quantum networks. The authors present them from three different angles: information-theoretic benchmarks, analytical tools, and simulation., AVS Quantum Science, 3 (1), ISSN:2639-0213

A quantum internet holds promise for achieving communication tasks that seem to be intractable by the current internet. The required functionality of a physical layer for such a quantum internet is to distribute entanglement efficiently to clients over a quantum network. A fundamental building block to design such efficient distribution of entanglement is to bound capacities of such quantum internet protocols. In this talk, we present a set of efficient linear programs to bound quantum/private capacities of quantum internet protocols, as well as their analytic upper/lower bounds. Our linear program is applied to bipartite cases, multi-pair cases, and a multi-partite case, covering almost all known situations.

In this paper, the shear strength of circular reinforced concrete (RC) columns was obtained using numerical models based on a modified compression field theory that enabled the sectional analysis o...

Twin-field (TF) quantum key distribution (QKD) was conjectured to beat the private capacity of a point-to-point QKD link by using single-photon interference in a central measuring station. This remarkable conjecture has recently triggered an intense research activity to prove its security. Here, we introduce a TF-type QKD protocol which is conceptually simpler than the original proposal. It relies on local phase randomization, instead of global phase randomization, which significantly simplifies its security analysis and is arguably less demanding experimentally. We demonstrate that the secure key rate of our protocol has a square-root improvement over the point-to-point private capacity, as conjectured by the original TF-QKD scheme., Comment: 11 pages, 5 figures

Despite the enormous theoretical and experimental progress made so far in quantum key distribution (QKD), the security of most existing QKD implementations is not rigorously established yet. A critical obstacle is that almost all existing security proofs make ideal assumptions on the QKD devices. Problematically, such assumptions are hard to satisfy in the experiments, and therefore it is not obvious how to apply such security proofs to practical QKD systems. Fortunately, any imperfections and security-loopholes in the measurement devices can be perfectly closed by measurement-device-independent QKD (MDI-QKD), and thus we only need to consider how to secure the source devices. Among imperfections in the source devices, correlations between the sending pulses are one of the principal problems. In this paper, we consider a setting-choice-independent correlation (SCIC) framework in which the sending pulses can present arbitrary correlations but they are independent of the previous setting choices such as the bit, the basis and the intensity settings. Within the framework of SCIC, we consider the dominant fluctuations of the sending states, such as the relative phases and the intensities, and provide a self-contained information theoretic security proof for the loss-tolerant QKD protocol in the finite-key regime. We demonstrate the feasibility of secure quantum communication within a reasonable number of pulses sent, and thus we are convinced that our work constitutes a crucial step toward guaranteeing implementation security of QKD., Comment: 27 pages, 5 figures

Surpassing the repeaterless bound is a crucial task on the way towards realizing long-distance quantum key distribution. In this paper, we focus on the protocol proposed by Azuma et al. in [Nature Communications 6, 10171 (2015)], which can beat this bound with idealized devices. We investigate the robustness of this protocol against imperfections in realistic setups, particularly the multiple-photon pair components emitted by practical entanglement sources. In doing so, we derive necessary conditions on the photon-number statistics of the sources in order to beat the repeaterless bound. We show, for instance, that parametric down-conversion sources do not satisfy the required conditions and thus cannot be used to outperform this bound., Comment: 21 pages, 8 figures

An all-optical network is identified as a promising infrastructure for fast and energy-efficient communication. Recently, it has been shown that its quantum version based on ‘all-photonic quantum repeaters’—inheriting, at least, the same advantages—expands its possibility to the quantum realm, that is, a global quantum internet with applications far beyond the conventional Internet. Here we report a proof-of-principle experiment for a key component for the all-photonic repeaters—called all-photonic time-reversed adaptive (TRA) Bell measurement, with a proposal for the implementation. In particular, our TRA measurement—based only on optical devices without any quantum memories and any quantum error correction—passively but selectively performs the Bell measurement only on single photons that have successfully survived their lossy travel over optical channels. In fact, our experiment shows that only the survived single-photon state is faithfully teleported without the disturbance from the other lost photons, as the theory predicts., Storage-free quantum repeaters represent a viable alternative to quantum-memory-based ones. Here, the authors propose a modified scheme for Bell state measurements which reduces the necessary resources for realising such an all-photonic repeater, and show a proof-of-principle implementation.

Fracture mechanics-based defect assessment procedures assume flaws are infinitely sharp cracks. However, this results in large safety factors for non-sharp flaws because of the loss of the plastic constraint. Fracture toughness tests were performed on four types of single-edge notched bend steel specimens with different degrees of plastic constraint, caused by fatigue cracks and machined notches with different notch root radii as well as by deep and shallow notches. This paper examines the differences in the stress states of the fatigue cracks and machined notches and the ability of the Weibull stress approach to predict the occurrence of brittle fractures under high and low plastic constraints in a unified manner.

The quantum internet holds promise for performing quantum communication, such as quantum teleportation and quantum key distribution, freely between any parties all over the globe. For such a quantum internet protocol, a general fundamental upper bound on the performance has been derived [K. Azuma, A. Mizutani, and H.-K. Lo, arXiv:1601.02933]. Here we consider its converse problem. In particular, we present a protocol constructible from any given quantum network, which is based on running quantum repeater schemes in parallel over the network. The performance of this protocol and the upper bound restrict the quantum capacity and the private capacity over the network from both sides. The optimality of the protocol is related to fundamental problems such as additivity questions for quantum channels and questions on the existence of a gap between quantum and private capacities., 5 pages, 2 figures

We provide a versatile upper bound on the number of maximally entangled qubits, or private bits, shared by two parties via a generic adaptive communication protocol over a quantum network when the use of classical communication is not restricted. Although our result follows the idea of Azuma et al. [Nat. Comm. 7, 13523 (2016)] of splitting the network into two parts, our approach relaxes their strong restriction, consisting of the use of a single entanglement measure in the quantification of the maximum amount of entanglement generated by the channels. In particular, in our bound the measure can be chosen on a channel-by-channel basis, in order to make it as tight as possible. This enables us to apply the relative entropy of entanglement, which often gives a state-of-the-art upper bound, on every Choi-simulable channel in the network, even when the other channels do not satisfy this property. We also develop tools to compute, or bound, the max-relative entropy of entanglement for channels that are invariant under phase rotations. In particular, we present an analytical formula for the max-relative entropy of entanglement of the qubit amplitude damping channel., Comment: 23 + 14 pages, 6 figures, close to published version

It has long been known that quantum networks will enable a whole new range of communication tasks to be undertaken. The simplest is quantum key distribution (QKD) and are commercially available but currently only operate securely over distances around 100 km. A significant advance has been the development of mdiQKD, a scheme where Alice and Bob send one photon at a time to an intermediate node where a Bell measurement is performed. This Bell measurement can only succeed when both Alice and Bob photons arrive at the same time and so the key rate is limited by the exponential losses in both fibres. It limits the practical distance keys can be generated to less than 400km. Spatial or temporal multiplexing is a natural solution to this where one stores the photons that independently arrive from Alice and Bob. Only when the immediate node has both does it perform the Bell measurement. This means we are effectively only limited by fibres losses in one half of the channel. It however means one requires quantum memories at this immediate node, a technically challenging feat and one that changes the general resources used in QKD schemes. In our spatial multiplexed approach, we propose the use of an “all photonic non-destructive measurement (QND)” to herald whether the photon has arrived successfully from either Alice or Bob. Optical switches can them be used to route these photons to the Bell measurement, meaning that we are only limited by the channel loss between either Alice and the immediate node or Bob and the intermediate node, but not both. Further this can achieved without the use of quantum memories at all. Only optical switches, single-photon sources, photon detectors, and passive feed-forward techniques are required. Our approach can be applied naturally to entanglement distribution and so has applications beyond QKD.

The ability to distribute entanglement over complex quantum networks is an important step towards a quantum internet. Recently, there has been significant theoretical effort, mainly focusing on the distribution of bipartite entanglement via a simple quantum network composed only of bipartite quantum channels. There are, however, a number of quantum information processing protocols based on multipartite rather than bipartite entanglement. Whereas multipartite entanglement can be distributed by means of a network of bipartite channels, a more natural way is to use a more general network, that is, a quantum broadcast network including quantum broadcast channels. In this work, we present a general frame- work for deriving upper bounds on the rates at which GHZ states or multipartite private states can be distributed among a number of different parties over an arbitrary quantum broadcast network. Our upper bounds are written in terms of the multipartite squashed entanglement, corresponding to a generalisation of recently derived bounds [K. Azuma et al., Nat. Commun. 7, 13523 (2016)]. We also discuss how lower bounds can be obtained by combining a generalisation of an aggregated quantum repeater protocol with graph theoretic concepts., Comment: 16 pages, 2 figures, published version

A series of tests, which reproduced brittle fracture starting from the region around the terminations of CJP (complete joint penetration) groove welded joints, was conducted. The joint models under study were portion of welded beam flange-to-through diaphragm joints in beam-to-column connections. Various artificial defects were installed in the welded joints prior to testing. This paper describes the effects of plastic constraint on brittle fracture from the welded joints with the defects at the ends of CJP groove welds. A toughness scaling model, which considers the effects of plastic constraint, was used for evaluating the occurrence of brittle fracture and was found to predict well the test results, compared with a conventional prediction method using fracture toughness Jc.

Recent field demonstrations of quantum key distribution (QKD) networks hold promise for unconditionally secure communication. However, owing to loss in optical fibres, the length of point-to-point links is limited to a hundred kilometers, restricting the QKD networks to intracity. A natural way to expand the QKD network in a secure manner is to connect it to another one in a different city with quantum repeaters. But, this solution is overengineered unless such a backbone connection is intercontinental. Here we present a QKD protocol that could supersede even quantum repeaters for connecting QKD networks in different cities below 800 km distant. Nonetheless, in contrast to quantum repeaters, this protocol uses only a single intermediate node with optical devices, requiring neither quantum memories nor quantum error correction. Our all-photonic ‘intercity' QKD protocol bridges large gaps between the conventional intracity QKD networks and the future intercontinental quantum repeaters, conceptually and technologically., Quantum key distribution (QKD) holds promise for unconditionally secure communication, but due to fibre losses distances are so far restricted to intracity. Here, the authors present an all optical QKD protocol that can connect distant cities without the need of quantum repeaters or quantum error correction.

Early phase prostate cancer is usually androgen-dependent, with the androgen/androgen receptor (AR) signaling pathway playing a central role. At this stage, the cancer responds well to androgen ablation therapy, but prostate cancers eventually acquire androgen independence and more aggressive phenotypes. Several studies, however, have shown that the majority of tumors still express functional AR, which is often amplified and mutated. To determine if the AR is a plausible therapeutic target, we investigated the anti-tumor effect of small interfering RNAs targeting the AR (siAR) in the human prostate cancer cells, LNCaP and 22Rv1, which express mutated AR. In both types of cells, transfection of siAR suppressed mutated AR expression and significantly reduced cell growth. Furthermore, atelocollagen-mediated systemic siAR administration markedly inhibited the growth of 22Rv1 cells subcutaneously xenografted in castrated nude mice. These results suggest that the AR is still a key therapeutic target even in androgen-independent prostate cancer (AIPC). Silencing of AR expression in AIPC opens promising therapeutic perspectives.

Nitric oxide (NO) may play a role in the established processes of learning and memory. We examined the effects of N ω -nitro- l -arginine methylester ( l -NAME), a nonselective inhibitor of NO synthase (NOS), on the performance of mice in a Y-maze task. l -NAME (100 mg/kg) markedly impaired spontaneous alternation behavior. However, galantamine (0.5 mg/kg) significantly attenuated this l -NAME-induced impairment. To clarify the molecular basis underlying galantamine's protective effects against l -NAME-induced impairment of spontaneous alternation behavior, we tested the ability of mecamylamine, an antagonist of nicotinic ACh receptor (nAChR), and scopolamine, an antagonist of muscarinic ACh receptor, to reduce galantamine's protective effects, and found that only the former had such an ability. Galantamine significantly also reduced l -NAME-induced decreases in NOx levels. However, mecamylamine cancelled galantamine's efficacy in countering the l -NAME-induced decrease in NOx levels. In the present study, we have determined that galantamine's protection against l -NAME-induced impairment of spontaneous alternation behavior in the Y-maze task might be mediated mainly by NOergic activation via the nAChR-related pathway.

PURPOSE We retrospectively evaluated the efficacy and toxicity of modified M-VAC therapy for locally advanced or metastatic urothelial carcinoma. PATIENTS AND METHOD From 1993 October to 2005 February, 28 patients were treated with modified M-VAC therapy and 25 of 28 patients had lesions suitable for the evaluation. The modified regimen was the combination of methotrexate at a dose of 30 mg/m2 on day 1, vinblastine at a dose of 3 mg/m2 on day 2, doxorubicin at a dose of 30 mg/m2 on day 2, and cisplatin at a dose of 70 mg/m2 on day 2 with courses repeated every three weeks. RESULTS The median number of cycle was 3 (1 to approximately 7 cycles). Six of 25 patients achieved complete response (CR) and six partial response (PR), resulting in a 48% response rate. With a median followup time of 65.6 months, the median survival was 9.3 months and the 1-year and 2-year survival rates were 33.5% and 9.6%, respectively. The median progression-free survival was 6.0 months. Grade 3 and 4 toxicities included neutropenia (84.4%), thrombocytopenia (40%), anemia (56%), febrile neutropenia (20%), nausea, vomiting (8%). CONCLUSION Although response rate of modified M-VAC therapy was similar to classic M-VAC therapy, but modified M-VAC therapy had shorter response duration and more frequent toxicities. We were not able to find the benefits of modified M-VAC therapy.