18,881 research outputs found
An alternating direction and projection algorithm for structure-enforced matrix factorization
Structure-enforced matrix factorization (SeMF) represents a large class of mathematical models appearing in various forms of principal component analysis, sparse coding, dictionary learning and other machine learning techniques useful in many applications including neuroscience and signal processing. In this paper, we present a unified algorithm framework, based on the classic alternating direction method of multipliers (ADMM), for solving a wide range of SeMF problems whose constraint sets permit low-complexity projections. We propose a strategy to adaptively adjust the penalty parameters which is the key to achieving good performance for ADMM. We conduct extensive numerical experiments to compare the proposed algorithm with a number of state-of-the-art special-purpose algorithms on test problems including dictionary learning for sparse representation and sparse nonnegative matrix factorization. Results show that our unified SeMF algorithm can solve different types of factorization problems as reliably and as efficiently as special-purpose algorithms. In particular, our SeMF algorithm provides the ability to explicitly enforce various combinatorial sparsity patterns that, to our knowledge, has not been considered in existing approaches
One-step implementation of multi-qubit conditional phase gating with nitrogen-vacancy centers coupled to a high-Q silica microsphere cavity
The diamond nitrogen-vacancy (NV) center is an excellent candidate for
quantum information processing, whereas entangling separate NV centers is still
of great experimental challenge. We propose an one-step conditional phase flip
with three NV centers coupled to a whispering-gallery mode cavity by virtue of
the Raman transition and smart qubit encoding. As decoherence is much
suppressed, our scheme could work for more qubits. The experimental feasibility
is justified.Comment: 3 pages, 2 figures, Accepted by Appl. Phys. Let
Quantum Privacy-Preserving Price E-Negotiation
Privacy-preserving price e-negotiation (3PEN) is an important topic of secure
multi-party computation (SMC) in the electronic commerce field, and the key
point of its security is to guarantee the privacy of seller's and buyer's
prices. In this study, a novel and efficient quantum solution to the 3PEN
problem is proposed, where the oracle operation and the qubit comparator are
utilized to obtain the comparative results of buyer's and seller's prices, and
then quantum counting is executed to summarize the total number of products
which meets the trading conditions. Analysis shows that our solution not only
guarantees the correctness and the privacy of 3PEN, but also has lower
communication complexity than those classical ones.Comment: 13 pages, 6 figure
Pentacarbonyl-1κ2 C,2κ3 C-[(diphenylphosphoryl)diphenylphosphane-1κP]-μ-ethane-1,2-dithiolato-1:2κ4 S,S′:S,S′-diiron(I)(Fe—Fe)
The dinuclear title compound, [Fe2(C2H4S2)(C24H20OP2)(CO)5] or (μ-SCH2CH2S-μ)Fe2(CO)5[Ph2PP(O)Ph2], contains a butterfly-shaped Fe2S2 core in which the Fe⋯Fe separation is 2.5275 (6) Å. One of the Fe atoms is also coordinated to three carbonyl ligands and the other to two carbonyl ligands and one phosphane ligand [Ph2PP(O)Ph2]. Both Fe-atom geometries could be described as grossly distorted octahedral and the Ph2PP(O)Ph2 ligand lies trans to the Fe⋯Fe link
Ultra-bright, ultra-broadband hard x-ray driven by laser-produced energetic electron beams
We propose a new method of obtaining a compact ultra-bright, ultra-broadband hard X-ray source. This X-ray source has a high peak brightness in the order of 1022 photons/(s mm2 mrad2 0.1\%BW), an ultrashort duration (10 fs), and a broadband spectrum (flat distribution from 0.1 MeV to 4 MeV), and thus has wide-ranging potential applications, such as in ultrafast Laue diffraction experiments. In our scheme, laser-plasma accelerators (LPAs) provide driven electron beams. A foil target is placed oblique to the beam direction so that the target normal sheath field (TNSF) is used to provide a bending force. Using this TNSF-kick scheme, we can fully utilize the advantages of current LPAs, including their high charge, high energy, and low emittance
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