Quantum Analog-Digital Conversion

Many quantum algorithms, such as Harrow-Hassidim-Lloyd (HHL) algorithm, depend on oracles that efficiently encode classical data into a quantum state. The encoding of the data can be categorized into two types; analog-encoding where the data are stored as amplitudes of a state, and digital-encoding where they are stored as qubit-strings. The former has been utilized to process classical data in an exponentially large space of a quantum system, where as the latter is required to perform arithmetics on a quantum computer. Quantum algorithms like HHL achieve quantum speedups with a sophisticated use of these two encodings. In this work, we present algorithms that converts these two encodings to one another. While quantum digital-to-analog conversions have implicitly been used in existing quantum algorithms, we reformulate it and give a generalized protocol that works probabilistically. On the other hand, we propose an deterministic algorithm that performs a quantum analog-to-digital conversion. These algorithms can be utilized to realize high-level quantum algorithms such as a nonlinear transformation of amplitude of a quantum state. As an example, we construct a "quantum amplitude perceptron", a quantum version of neural network, and hence has a possible application in the area of quantum machine learning.Comment: 7 page

Measurement-free topological protection using dissipative feedback

Protecting quantum information from decoherence due to environmental noise is vital for fault-tolerant quantum computation. To this end, standard quantum error correction employs parallel projective measurements of individual particles, which makes the system extremely complicated. Here we propose measurement-free topological protection in two dimension without any selective addressing of individual particles. We make use of engineered dissipative dynamics and feedback operations to reduce the entropy generated by decoherence in such a way that quantum information is topologically protected. We calculate an error threshold, below which quantum information is protected, without assuming selective addressing, projective measurements, nor instantaneous classical processing. All physical operations are local and translationally invariant, and no parallel projective measurement is required, which implies high scalability. Furthermore, since the engineered dissipative dynamics we utilized has been well studied in quantum simulation, the proposed scheme can be a promising route progressing from quantum simulation to fault-tolerant quantum information processing.Comment: 17pages, 6 figure

Lessons from Japan's banking crisis, 1991 - 2005

The Japanese government's response to the financial crisis in the 1990s was late, unprepared and insufficient; it failed to recognize the severity of the crisis, which developed slowly; faced no major domestic or external constraints; and lacked an adequate legal framework for bank resolution. Policy measures adopted after the 1997 - 1998 systemic crisis, supported by a newly established comprehensive framework for bank resolution, were more decisive. Banking sector problems were eventually resolved by a series of policies implemented from that period, together with an export-led economic recovery. Japan's experience suggests that it is vital for a government not only to recapitalize the banking system but also to provide banks with adequate incentives to dispose of troubled assets from their balance sheets, even if that required the government to mobilize regulatory measures to do so, as was done in Japan in 2002. Economic stagnation can cause new nonperforming loans to emerge rapidly, and deplete bank capital. If the authorities do not address the banking sector problem promptly, then the crisis will prolong and economic recovery will be substantially delayed

Boosting computational power through spatial multiplexing in quantum reservoir computing

Quantum reservoir computing provides a framework for exploiting the natural dynamics of quantum systems as a computational resource. It can implement real-time signal processing and solve temporal machine learning problems in general, which requires memory and nonlinear mapping of the recent input stream using the quantum dynamics in computational supremacy region, where the classical simulation of the system is intractable. A nuclear magnetic resonance spin-ensemble system is one of the realistic candidates for such physical implementations, which is currently available in laboratories. In this paper, considering these realistic experimental constraints for implementing the framework, we introduce a scheme, which we call a spatial multiplexing technique, to effectively boost the computational power of the platform. This technique exploits disjoint dynamics, which originate from multiple different quantum systems driven by common input streams in parallel. Accordingly, unlike designing a single large quantum system to increase the number of qubits for computational nodes, it is possible to prepare a huge number of qubits from multiple but small quantum systems, which are operationally easy to handle in laboratory experiments. We numerically demonstrate the effectiveness of the technique using several benchmark tasks and quantitatively investigate its specifications, range of validity, and limitations in detail.Comment: 15 page

12(th )international conference on human retrovirology: HTLV and related retroviruses

The 12(th )International Conference on Human Retrovirology: HTLV and Related Retroviruses, was held at the Half Moon Hotel in Montego Bay, Jamaica, from June 22(nd )to June 25(th )2005. The scientific conference, sponsored by the International Retrovirology Association, is held biennially at rotating international venues around the world. The meeting brings together basic scientists, epidemiologists and clinical researchers to discuss findings to prevent HTLV infection or develop new therapies against HTLV-mediated diseases. The Association fosters the education and training of young scientists to bring new approaches to the complex problems of HTLV research, such as translational research to bring findings from the laboratory into clinical trials that benefit HTLV-infected patients. The breadth and quality of research presentations and workshops at the 12(th )International Conference indicate that these goals are being accomplished. As HTLV research enters its third decade a new generation of scientists face many challenges. However, HTLV scientists and clinicians displayed exciting new approaches and discoveries during plenary talks and poster sessions. The conference encouraged research in HTLV infections and disease, fostered collaborations, and stimulated new partnerships between clinicians and scientists to encourage clinical trials and novel therapeutic interventions

Effects of Drive System Lubricant Additives upon Rolling Fatigue of Carburized and Hardened Steel Rollers

To clarify the effects of a drive system lubricant additive upon rolling fatigue of rollers manufactured from carburized and hardened steel, three types of oil were used as lubricants: one mineral base oil and the other two mineral base oils to which an S-P additive package and ATF additive package were added, respectively. These specimens were tested for sliding/rolling fatigue and examined for failure on the surface, rolling fatigue strength, and other properties. Roller surface temperatures and inter-roller frictional coefficients were found scarcely affected by the type of oil used. Irrespective of the difference in oil type, failure on the surface was found to be entirely spalling attributable to cracks generated in the subsurface. The depth at which spalling cracks had taken place was found nearly coincident with the depth at which a ratio of reversing orthogonal shear stress to hardness had amplitude A(Tyz/Hv) maximized. These depths were larger as Hertz stress became more prominent. Nevertheless, they were found hardly affected by the type of oil. Although rolling fatigue strength did not show a significant difference dependent upon the type of oil, it may be said that fatigue life would be somewhat negatively affected by an extreme pressure coated film with a content of sulfur and phosphorus

THE ANALYSIS OF RACE PACING IN ELITE COMPETITIVE LONG-DISTANCE SPEED SKATING

The purpose of this study was to investigate the characteristics of racing pattern adopted by elite male speed skaters in official 5000m race. Twenty-four male skaters, who participated at the World Single Distances Speed Skating Championships 2008, were recorded using video camera (60Hz). The top group (top12 ranked skaters) was significantly faster than the 2nd group (13th to 24th ranked skaters) from 350m line to the finishing line (

MN-Pair Contrastive Damage Representation and Clustering for Prognostic Explanation

For infrastructure inspections, damage representation does not constantly match the predefined classes of damage grade, resulting in detailed clusters of unseen damages or more complex clusters from overlapped space between two grades. The damage representation has fundamentally complex features; consequently, not all the damage classes can be perfectly predefined. The proposed MN-pair contrastive learning method helps to explore an embedding damage representation beyond the predefined classes by including more detailed clusters. It maximizes both the similarity of M-1 positive images close to an anchor and dissimilarity of N-1 negative images using both weighting loss functions. It learns faster than the N-pair algorithm using one positive image. We proposed a pipeline to obtain the damage representation and used a density-based clustering on a 2-D reduction space to automate finer cluster discrimination. We also visualized the explanation of the damage feature using Grad-CAM for MN-pair damage metric learning. We demonstrated our method in three experimental studies: steel product defect, concrete crack, and the effectiveness of our method and discuss future works.Comment: 8 pages, 10 figures, 3 table