Quantum interactive proofs and the complexity of separability testing

We identify a formal connection between physical problems related to the detection of separable (unentangled) quantum states and complexity classes in theoretical computer science. In particular, we show that to nearly every quantum interactive proof complexity class (including BQP, QMA, QMA(2), and QSZK), there corresponds a natural separability testing problem that is complete for that class. Of particular interest is the fact that the problem of determining whether an isometry can be made to produce a separable state is either QMA-complete or QMA(2)-complete, depending upon whether the distance between quantum states is measured by the one-way LOCC norm or the trace norm. We obtain strong hardness results by proving that for each n-qubit maximally entangled state there exists a fixed one-way LOCC measurement that distinguishes it from any separable state with error probability that decays exponentially in n.Comment: v2: 43 pages, 5 figures, completely rewritten and in Theory of Computing (ToC) journal forma

PENINGKATAN KINERJA SUPPLY CHAIN MANAGEMENT MENGGUNAKAN PENDEKATAN SUPPLY CHAIN OPERATIONS REFERENCE (STUDI KASUS: PT XYZ)

Supply Chain Operations Reference (SCOR) merupakan sebuah metode pada konsep supply chain yang salah satunya berfungsi untuk meningkatkan kinerja rantai pasok di perusahaan. Pengukuran kinerja rantai pasok pada PT XYZ berfungsi sebagai tolak ukur supply chain yang sudah berjalan selama ini. PT XYZ yang bergerak di bidang industri perikanan dengan spesifik produk yaitu ikan pelagis beku. Ketergantungan perusahaan dengan nelayan dalam hal pasokan bahan baku tergolong tinggi. Hal ini akan berpengaruh terhadap kesanggupan perusahaan dalam menyanggupi permintaan pasar yang ada. Penelitian ini bertujuan untuk mengukur kinerja rantai pasok berdasarkan atribut kinerja reliability serta melakukan perbaikan menggunakan diagram fishbone. Atribut kinerja reliability terdiri dari metrik delivery performance dan perfect order fullfilment. Pada tahap pengolahan data didapatkan nilai delivery performance sebesar 92 % dan nilai perfect order fullfilment sebesar 88%. Rekapitulasi dan analisis hasil pengukuran dengan membandingkan nilai dari target perusahaan dan benchmark dari Supply Chain Council (SCC). Analisis metrik kinerja yang belum tercapai dan usulan perbaikan menggunakan diagram fishbone. Usulan perbaikan yang didapatkan dari diagram fishbone antara lain training driver, period maintenance, scheduling jam kerja, penambahan tenaga kerja (sopir), alternatif rute, pengurusan surat perizinan berbasis online, pengadaan kapal milik perusahaan, dan menjaga hubungan antara pihak perusahaan dan supplier.Kata kunci: Supply Chain, Supply Chain Operations Reference, Customer Facing, Reliability

The structure and petrology of the Cnoc nan Cuilean Intrusion, Loch Loyal Syenite Complex, NW Scotland

In NW Scotland, several alkaline intrusive complexes of Silurian age intrude the Caledonian orogenic front. The most northerly is the Loch Loyal Syenite Complex, which is divided into three separate intrusions (Ben Loyal, Beinn Stumanadh and Cnoc nan Cuilean). Mapping of the Cnoc nan Cuilean intrusion shows two main zones: a Mixed Syenite Zone (MZ) and a Massive Leucosyenite Zone (LZ), with a gradational contact. The MZ forms a lopolith, with multiple syenitic lithologies, including early basic melasyenites and later felsic leucosyenites. Leucosyenite melts mixed and mingled with melasyenites, resulting in extreme heterogeneity within the MZ. Continued felsic magmatism resulted in formation of the relatively homogeneous LZ, invading western parts of the MZ and now forming the topographically highest terrane. The identification of pegmatites, microgranitic veins and unusual biotite-magnetite veins demonstrates the intrusion's complex petrogenesis. Cross-sections have been used to create a novel 3D GoCad™ model contributing to our understanding of the intrusion. The Loch Loyal Syenite Complex is known to have relatively high concentrations of rare earth elements (REEs), and thus the area has potential economic and strategic value. At Cnoc nan Cuilean, abundant REE-bearing allanite is present within melasyenites of the MZ. Extensive hydrothermal alteration of melasyenites here formed steeply dipping biotite-magnetite veins, most enriched in allanite and other REE-bearing accessories. This study has thus identified the area of greatest importance for further study of REE enrichment processes in the Cnoc nan Cuilean intrusion

Peer choice in CEO compensation

Current research shows that firms are more likely to benchmark against peers that pay their Chief Executive Officers (CEOs) higher compensation, reflecting self serving behavior. We propose an alternative explanation: the choice of highly paid peers represents a reward for unobserved CEO talent. We test this hypothesis by decomposing the effect of peer selection into talent and self serving components. Consistent with our prediction, we find that the association between a firm's selection of highly paid peers and CEO pay mostly represents compensation for CEO talent

Generating derivative structures: Algorithm and applications

We present an algorithm for generating all derivative superstructures--for arbitrary parent structures and for any number of atom types. This algorithm enumerates superlattices and atomic configurations in a geometry-independent way. The key concept is to use the quotient group associated with each superlattice to determine all unique atomic configurations. The run time of the algorithm scales linearly with the number of unique structures found. We show several applications demonstrating how the algorithm can be used in materials design problems. We predict an altogether new crystal structure in Cd-Pt and Pd-Pt, and several new ground states in Pd-rich and Pt-rich binary systems

Spatio-temporal patterns in the postglacial flooding of the Great Barrier Reef shelf, Australia

The shelf of the Great Barrier Reef (GBR) was progressively marine flooded from the last glaciation maximum (LGM) (ca 20 ka BP) until the last sea-level highstand (ca 6 ka BP), affecting the depositional evolution of the GBR margin and associated deposits. However, the physiographic variables related to this process have not been fully characterized, especially in relation to the sedimentary processes at the shelf margin. For this study, we used a bathymetric model of the entire shelf and a shelf margin sub-set, divided into 33 latitudinal zones. Postglacial marine flooding was simulated and flooded area (km2), flooding magnitude (km2 per sea-level increment), flooding rate (km2. ky−1) and coastline length (km) were estimated for each zone, from 130 m to 0 m below present sea level, representing the period from 20 ka to 6 ka BP. Our results show that the postglacial marine flooding did not occur uniformly and that some sub-regions (e.g. the southern-central GBR) had early and rapid flooding. Coastal complexity increased in the mid-postglacial, reaching maximum values at around 9 ka BP. This reflects a coastal landscape evolving from a linear, laterally connected coast to a complex coast dominated by estuaries and lagoons, partly returning to its initial linearity during highstand. Flooding trends and geological evidence make two depositional relationships apparent. Firstly, the timing and magnitude of the off-shelf sediment flux appears linked to the presence and orientation of a shelf-edge rim, and to the extension and morphology of the evolving drainage network. Secondly, the periods of shelf-edge reef development and demise seem to respond to the remobilisation, trapping or redirection of fine sediments. We propose a sedimentation model for the shelf margin and the slope driven by the interplay of sea-level rise and shelf physiography, and we highlight two fundamental processes: (1) the cross-shelf sediment transport related to coastline retreat under rising sea levels, and (2) the effectiveness of transient embayments in redirecting or trapping sediments. The quantifications provided in this study have implications in the estimation of Pleistocene carbonate budgets and the atmospheric carbon cycle, as well as for past human migrations