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Abstract Quantum teleportation exemplifies how the transmission of quantum information starkly differs from that of classical information and serves as a key protocol for quantum communication and quantum computing. While an ideal teleportation protocol requires noiseless quantum channels to share a pure maximally entangled state, the reality is that shared entanglement is often severely degraded due to various decoherence mechanisms. Although the quantum noise induced by the decoherence is indeed a major obstacle to realizing a near-term quantum network or processor with a limited number of qubits, the methodologies considered thus far to address this issue are resource-intensive. Here, we demonstrate a protocol that allows optimal quantum teleportation via noisy quantum channels without additional qubit resources. By analyzing teleportation in the framework of generalized quantum measurement, we optimize the teleportation protocol for noisy quantum channels. In particular, we experimentally demonstrate that our protocol enables to teleport an unknown qubit even via a single copy of an entangled state under strong decoherence that would otherwise preclude any quantum operation. Our work provides a useful methodology for practically coping with decoherence with a limited number of qubits and paves the way for realizing noisy intermediate-scale quantum computing and quantum communication.

Abstract One of the common conceptions of nature, typically derived from the experiences with classical systems, is that attributes of the matter coexist with the substance. In the quantum regime, however, the quantum particle itself and its physical property may be in spatial separation, known as the quantum Cheshire cat effect. While there have been several reports to date on the observation of the quantum Cheshire cat effect, all such experiments are based on first-order interferometry and destructive projection measurement, thus allowing simple interpretation due to measurement-induced disturbance and also subject to trivial interpretation based on classical waves. In this work, we report an experimental observation of the quantum Cheshire cat effect with noninvasive weak quantum measurement as originally proposed. The use of the weak-measurement probe has allowed us to identify the location of the single photon and that of the disembodied polarization state in a quantum interferometer. The weak-measurement probe based on two-photon interference makes our observation unable to be explained by classical physics. We furthermore elucidate the quantum Cheshire cat effect as quantum interference of the transition amplitudes for the photon and the polarization state which are directly obtained from the measurement outcomes or the weak values. Our work not only reveals the true quantum nature of Cheshire cat effect but also sheds light on a comprehensive understanding for the counter-intuitive quantum phenomena.

A small leak occurring on the surface of a fuel rod due to damage exposes UO2 to a steam atmosphere. During this time, fission gas trapped inside the fuel rod leaks out, and the gas leakage can be increased due to UO2 oxidation. Numerous studies have focused on the steam oxidation and its thermodynamic calculation in UO2. However, the thermodynamic calculation of the UO2 oxidation in a pressurized water reactor (PWR) environment has not been studied extensively. Moreover, the kinetics of the oxidation of UO2 pellet also has not been investigated. Therefore, in this study, the thermodynamics of UO2 oxidation under steam injection due to a damaged fuel rod in a PWR environment is studied. In addition, the diminishing radius of the UO2 pellet with time in the PWR environment was calculated through an experiment simulating the initial time of steam injection at the puncture.

In a quantum network involving multiple communicating parties, an important goal is to establish high-quality pairwise entanglement among the users without introducing multiple entangled-photon sources which would necessarily complicate the overall network setup. Moreover, it is preferable that the pairwise entanglement of photons is in the time-bin degree of freedom as the photonic time-bin qubit is ideally suited for fiber-optic distribution. Here, we report an experimental demonstration of a field-deployable quantum communication network involving multiple users, all of whom share pairwise entanglement in the time-bin degree of freedom of photons. In particular, by utilizing a single spontaneous-parametric down-conversion source which produces a broadband pair of photons and the wavelength-division demultiplexing/multiplexing technology, all the communicating parties within the network are always simultaneously ready for quantum communication. To further demonstrate the practical feasibility of a quantum network with time-bin entanglement over a wavelength-multiplexed fiber network, we demonstrate entangled-photon quantum key distribution with three users, each separated by 60 km of optical fibers.

A taxonomic study of the genus Synchita Hellwig in Korea is presented. Two species, Synchita hayashii (Sasaji) and S. ussuriensis (Iablokoff-Khnzorian), are newly added to the Korean fauna. A key to species in East Asia, descriptions, habitus photographs, and illustrations of diagnostic characters of the Korean species are provided.

The ladybird beetle (Coleoptera) is composed of approximately 6,000 species around the world belonging to about 360 genera. However, the genus of Horniolus of family Coccinellidae has not been recorded in Korean peninsula. Four adult specimens were collected from Daedun Mountain, South Korea. Horniolus fortunatus is distinguished from other Horniolus species by body length 2.7–2.9mm; pronotum dark with two reddish brown markings laterally; elytra black with four transverse markings; abdominal postcoxal line complete; penis widest at base and convergent at apical part; and distinct shorter than parameres. Habitus photographs, diagnosis, and line-drawings of male genitalia are provided with a key to the species of genus Horniolus in Palearctic region. Keywords: Coleoptera, Coccinellidae, Korean Peninsula, New record, Taxonomy

Decoherence due to the unwanted interaction between a quantum system and environment leads to the degradation of quantum coherence. In particular, for an entangled state, decoherence makes a loss of entanglement and Bell nonlocality known as entanglement sudden death (ESD), and Bell nonlocality sudden death (BNSD). Here, we theoretically investigate the entanglement and Bell nonlocality of a bipartite entangled state under three types of decoherence, amplitude damping, phase damping, and depolarizing. Our result provides the bound of decoherence strength that does not lose the entanglement and Bell nonlocality. In addition, we find two interesting features. One is that the entanglement can survive even though one of the entangled qubits is affected by a large strength of decoherence if the other qubit is affected by a small enough strength of decoherence except for the depolarizing. The second one is that when a specific form of entangled state is under amplitude damping, the Bell nonlocality shows an asymmetric behavior respect to the decoherence strengths on each qubit. Our work provides comprehensive information on ESD and BNSD for the bipartite entangled state which will be useful to implement quantum information processing in the presence of decoherence.

Weak measurements constitute a powerful tool for metrology, tomography and even foundations, but in most cases could be explained classically. Here, the authors characterise a quantum channel using sequential weak value measurements of two incompatible observables utilising two-photon quantum interference.

We introduce a generalized concept of quantum teleportation in the framework of quantum measurement and reversing operation. Our framework makes it possible to find an optimal protocol for quantum teleportation enabling a faithful transfer of unknown quantum states with maximum success probability up to the fundamental limit of the no-cloning theorem. Moreover, an optimized protocol in this generalized approach allows us to overcome noise in quantum channel beyond the reach of existing teleportation protocols without requiring extra qubit resources. Our proposed framework is applicable to multipartite quantum communications and primitive functionalities in scalable quantum architectures.

A list of the 646 described species of Staphylinidae in Korea is presented. The list is in taxonomic sequence by subfamily, tribe, and genus and includes 215 genera in 55 tribes and 18 subfamilies. We provide the page reference of the original description of every species and genus listed, of many synonyms, and of all the Korean records. The list provides distribution of all the species by country (and for the larger countries, by province or state). A brief taxonomic history of the Korean Staphylinidae is presented. A complete bibliography is provided.

In this study, a taxonomic study of the Korean Salpingidae Leach is presented. Four species under the three genera are recognized. Genera and species Chilopeltis laevipennis (Marseul, 1876) and Salpingus depressifrons Nikitsky & Belov, 1983 are reported for the first time in the Korean Peninsula. A key to the Korean Salpingidae species, habitus photographs, and line drawing of male genitalia of S. depressifrons are provided.

We train convolutional neural networks to predict whether or not a set of measurements is informationally complete to uniquely reconstruct any given quantum state with no prior information. In addition, we perform fidelity benchmarking based on this measurement set without explicitly carrying out state tomography. The networks are trained to recognize the fidelity and a reliable measure for informational completeness. By gradually accumulating measurements and data, these trained convolutional networks can efficiently establish a compressive quantum-state characterization scheme by accelerating runtime computation and greatly reducing systematic drifts in experiments. We confirm the potential of this machine-learning approach by presenting experimental results for both spatial-mode and multiphoton systems of large dimensions. These predictions are further shown to improve when the networks are trained with additional bootstrapped training sets from real experimental data. Using a realistic beam-profile displacement error model for Hermite–Gaussian sources, we further demonstrate numerically that the orders-of-magnitude reduction in certification time with trained networks greatly increases the computation yield of a large-scale quantum processor using these sources, before state fidelity deteriorates significantly.

Coleoptera is a group of insects that are most diverse among insect resources. Although used as indicator species and applied in developing new drugs, it is difficult to identify them quickly. Since the development of a method using mitochondrial DNA information for identification, studies have been conducted in Korea to swiftly and accurately identify species. The National Science Museum of Korea (NSMK) has been collecting and morphologically identifying domestic reference insects since 2013, and building a database of DNA barcodes with digital images. The NSMK completed construction of a database of digital images and DNA barcodes of 60 beetle species in the Korean National Research Information System. A total of 179 specimens and 60 species were used for the analysis, and the averages of intraspecific and interspecific variations were 0.70±0.45% and 26.34±6.01%, respectively, with variation rates ranging from 0% to 1.45% and 9.83% to 56.23%, respectively.

Performance tests were carried out for a microchannel printed circuit heat exchanger (PCHE), which was fabricated with micro photo-etching and diffusion bonding technologies. The microchannel PCHE was tested for Reynolds numbers in the range of 100‒850 varying the hot-side inlet temperature between 40 °C–50 °C while keeping the cold-side temperature fixed at 20 °C. It was found that the average heat transfer rate and heat transfer performance of the countercurrrent configuration were 6.8% and 10%‒15% higher, respectively, than those of the parallel flow. The average heat transfer rate, heat transfer performance and pressure drop increased with increasing Reynolds number in all experiments. Increasing inlet temperature did not affect the heat transfer performance while it slightly decreased the pressure drop in the experimental range considered. Empirical correlations have been developed for the heat transfer coefficient and pressure drop factor as functions of the Reynolds number.

A taxonomic study of the genus Homalota Mannerheim in Korea is presented. Five species are recognized, one of which, Homalota serrata (Assing), comb. n. is transferred from Anomognathus Solier. Homalota fraterna (Sharp), H. mikado Likovský, H. sauteri Bernhauer, and H. serrata are newly added to the Korean fauna. A key, descriptions, and illustrations of the diagnostic characters are provided.

An in-pile performance test of HANA claddings was conducted at up to 67 GWD/MTU in the Halden research reactor in Norway over a 6.5 year period. Four types of HANA claddings (HANA-3, HANA-4, HANA-5, and HANA-6) and a reference Zircaloy-4 cladding were used for the in-pile test. The evaluation parameters of the HANA claddings were the corrosion behavior, dimensional changes, hydrogen uptake, and tensile strength after the claddings were tested under the simulated operation conditions of a Korean commercial reactor. The oxide thickness ranged from 15 to 37 mm at a high flux region in the test rods, and all HANA claddings showed corrosion resistance superior to the Zircaloy-4 cladding. The creep-down rate of all HANA claddings was lower than that of the Zircaloy-4 cladding. In addition, the hydrogen content of the HANA claddings ranged from 54 to 96 wppm at the high heat flux region of the test rods, whereas the hydrogen content of the Zircaloy-4 cladding was 119 wppm. The tensile strength of the HANA and Zircaloy-4 claddings was similarly increased when compared to the un-irradiated claddings owing to the radiation-induced hardening.

We report an experimental demonstration of the nonclassical stationary light pulse (SLP) in a cold atomic ensemble. A single collective atomic excitation is created and heralded by detecting a Stokes photon in the spontaneous Raman scattering process. The heralded single atomic excitation is converted into a single stationary optical excitation or the single-photon SLP, whose effective group velocity is zero, effectively forming a trapped single-photon pulse within the cold atomic ensemble. The single-photon SLP is then released from the atomic ensemble as an anti-Stokes photon after a specified trapping time. The second-order correlation measurement between the Stokes and anti-Stokes photons reveals the nonclassical nature of the single-photon SLP. Our work paves the way toward quantum nonlinear optics without a cavity.

In the original version of this Article, the penultimate sentence of the second paragraph of the “Schematic and theory” section of the Results originally incorrectly read as “For instance, choosing θA = π/4, 0, −π/8 and π/8 rotates the bases |0>, |1>, |+>, and |−> into |1>, thereby implementing the observableÂ=|0>

A fiber-based photon-pair source in the telecom C-band is suitable for quantum information science including quantum communications. Spontaneous four-wave mixing effects are known to create photon pairs that are slightly detuned from the pump wavelength only in the anomalous group-velocity-dispersion (GVD) regime. Here, we achieve high-quality photon-pair generation slightly detuned from the pump wavelength in the normal GVD regime through a dispersion shifted fiber, for the first time. The photon pairs in C-band exhibit strong temporal correlation with each other and excellent heralded anti-bunching property. This photon-pair generation scheme can be exploited as telecom-band quantum light sources for quantum information applications.

Since improvement of wireless communication, IP based mobility management protocols have been studied to provide seamless communication and mobility management. The vehicular ad hoc network (VANET) is one of mobility management protocols, especially providing seamless connection with inter/intra/inner vehicle communication. However, each vehicle moves fast that causes short-lived connections with Access Router (AR). Based on vehicles' characteristic, it is hard to provide the availability of IP services in VANET. The most critical issue of the design of scalable routing algorithm is to provide robustness of frequent path disruption caused by vehicles' mobility. In this paper, we pursue the characteristics of vehicles' mobility and analyze them. With the navigation information which is one of vehicles' mobility characteristics, we classify the mobility into intrahighway mobility and global mobility management. Furthermore, we propose mobility management scheme based on route prediction in VANET. Handoffs with intrahighway mobility are managed locally and transparency is provided to CHs, while global mobility is managed with Mobile IPv6. Finally, through the numerical analysis, we show that proposed mobility management protocol reduces handoff latency, signaling costs, and packet loss.

Since the fire causes serious disasters, fire detection has been an important study to protect human life. Based on the deficiencies of existing fire detection on real-time and monitoring accuracy, the wireless sensor network technique for fire detection was introduced and needed. In this paper, we proposed the fire detection algorithm in video sequences on wireless sensor network. The proposed fire detection algorithm processes visual information acquired through static camera that lets us incorporate the algorithm to CCTV surveillance system, and therefore does not require an additional expanses on conventional fire sensors. Fire detection method based on motion information, any input image, is compared to background in order to identify foreground. Background is statistically modeled by mixture of Gaussians. To detect the foreground of video sequences, the proposed color detection algorithm was performed in RGB space. The procedure of algorithm eliminates all objects that do not fulfill color requirements without fire-like objects. And the change map and blob's area are computed, change map shows temporal variation of pixel between two consecutive binary frames, and percentage area increase or decrease characterizes a fire property for swinging.

Interferometric signals are degraded by decoherence, which encompasses dephasing, mixing and any distinguishing which-path information. These three paradigmatic processes are fundamentally different, but, for coherent, single-photon and $N00N$ -states, they degrade interferometric visibility in the very same way, which impedes the diagnosis of the cause for reduced visibility in a single experiment. We introduce a versatile formalism for many-boson interferometry based on double-sided Feynman diagrams, which we apply to a protocol for differential decoherence diagnosis: twin-Fock states $\mid N,N\rangle $ with $N\geqslant 2$ reveal to what extent decoherence is due to path distinguishability or to mixing, while double-Fock superpositions $\mid N:M\rangle =\left( \mid N,M\rangle +\mid M,N\rangle \right)/\sqrt{2}$ with $N\gt M\gt 0$ additionally witness the degree of dephasing. Hence, double-Fock superposition interferometry permits the differential diagnosis of decoherence processes in a single experiment, indispensable for the assessment of interferometers.

A recent work (Björk and Shabbir 2014 New J. Phys. http://dx.doi.org/10.1088/1367-2630/16/1/013006 16 http://dx.doi.org/10.1088/1367-2630/16/1/013006 ) claims that nonmonotonic structures found in the many-particle quantum-to-classical transition (Ra et al 2013 Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1206910110 110 http://dx.doi.org/10.1073/pnas.1206910110 ; Tichy et al 2011 Phys. Rev. A http://dx.doi.org/10.1103/PhysRevA.83.062111 83 http://dx.doi.org/10.1103/PhysRevA.83.062111 ) are not exclusive to the many-body domain, but they also appear for single-photon as well as for semi-classical systems. We show that these situations, however, do not incorporate any quantum-to-classical transition, which makes the claims unsustainable.