Minimum-energy pulses for quantum logic cannot be shared

We show that if an electromagnetic energy pulse with average photon number is used to carry out the same quantum logical operation on a set of N atoms, either simultaneously or sequentially, the overall error probability in the worst case scenario (i.e., maximized over all the possible initial atomic states) scales as N^2/. This means that in order to keep the error probability bounded by N\epsilon, with \epsilon ~ 1/, one needs to use N/\epsilon photons, or equivalently N separate "minimum-energy'' pulses: in this sense the pulses cannot, in general, be shared. The origin for this phenomenon is found in atom-field entanglement. These results may have important consequences for quantum logic and, in particular, for large-scale quantum computation.Comment: To appear in Phys. Rev. A, Rapid Communication

Quantum limits in interferometric measurements

Quantum noise limits the sensitivity of interferometric measurements. It is generally admitted that it leads to an ultimate sensitivity, the ``standard quantum limit''. Using a semi-classical analysis of quantum noise, we show that a judicious use of squeezed states allows one in principle to push the sensitivity beyond this limit. This general method could be applied to large scale interferometers designed for gravitational wave detection.Comment: 4 page

Gate fidelity of arbitrary single-qubit gates constrained by conservation laws

Recent investigations show that conservation laws limit the accuracy of gate operations in quantum computing. The inevitable error under the angular momentum conservation law has been evaluated so far for the CNOT, Hadamard, and NOT gates for spin 1/2 qubits, while the SWAP gate has no constraint. Here, we extend the above results to general single-qubit gates. We obtain an upper bound of the gate fidelity of arbitrary single-qubit gates implemented under arbitrary conservation laws, determined by the geometry of the conservation law and the gate operation on the Bloch sphere as well as the size of the ancilla.Comment: Title changed; to appear in J. Phys. A: Math. Theor.; 19 pages, 2 figure

Control del proceso de deshumidificación de muros con georradar. Un edificio patrimonial como caso de estudio

En edificios históricos son conocidos los efectos nocivos de la presencia de humedad en muros, que deteriora detalles de ornamentación, conjuntamente con los componentes de la mampostería que conforma su propia estructura. Es el caso de la Iglesia Nuestra Señora de la Viña (Salta, Argentina), edificio del s. XIX que presentaba manifestaciones patológicas características de las producidas por la presencia de humedad ascendente. Las tareas de recuperación de las superficies exteriores fueron realizadas una vez que el sistema instalado (por electrólisis) deshumidificó los muros. La elevada inversión realizada requiere de un control periódico de la eficacia del sistema. En este trabajo se presentan los fundamentos y los resultados obtenidos con el empleo de georradar como recurso no destructivo para controlar el sistema de deshumidifación, cuya principal ventaja es la de poder detectar en forma precoz a lo largo del tiempo alguna falla en el sistema, evitando en forma indefinida la aparición de nuevas manifestaciones patológicas por humedad ascendente.In historical buildings the harmful effects in masonry due to moisture are well known, as it affects ornamentation and the components of the masonry which is also the building's structure. That is the case of the church Nuestra Señora de la Viña (Salta, Argentina), a XIX cent. building which presented typical pathological symptoms caused by rising damp. An electro physical system was installed in order to dehumidificate the masonry and external surfaces were subsequently recovered. This high investment requires a periodical control of the system's efficiency. This article presents the foundations of and the results obtained by using an impulse radar as a non-destructive resource to control the dehumidification system. Its main advantage is the early detecting of a failure in the system and so avoiding new pathological symptoms caused by rising damp.Fil: Gea, S.. Universidad Nacional de Salta. Facultad de Ingenieria; ArgentinaFil: Quinteros, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones Para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones Para la Industria Química; ArgentinaFil: Nallim, Liz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones Para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones Para la Industria Química; Argentin

Constraints for quantum logic arising from conservation laws and field fluctuations

We explore the connections between the constraints on the precision of quantum logical operations that arise from a conservation law, and those arising from quantum field fluctuations. We show that the conservation-law based constraints apply in a number of situations of experimental interest, such as Raman excitations, and atoms in free space interacting with the multimode vacuum. We also show that for these systems, and for states with a sufficiently large photon number, the conservation-law based constraint represents an ultimate limit closely related to the fluctuations in the quantum field phase.Comment: To appear in J. Opt. B: Quantum Semiclass. Opt., special issue on quantum contro

Pengaruh Persediaan Bahan Baku, dan Pemeliharaan Peralatan, terhadap Proses Produksi dengan Kualitas Bahan Baku sebagai Variabel Moderating

Penelitian ini merupakan studi tentang “Pengaruh Persediaan Bahan Baku, dan Pemeliharaan Peralatan, terhadap Proses Produksi dengan Kualitas Bahan Baku sebagai variabel moderating”.Perusahaan ini telah berdiri sejak tahun 2009 sampel yang digunakan dalam penelitian ini adalah sampel purposive sampling, dimana seluruh anggota populasi sebanyak 60 bulan diberikan kesempatan yang sama untuk menjadi responden. Kriteria pengambilan sampelnya meliputi :1.Laporan hasil proses produksi selama 60 bulan2.Periode Januari 2013- Desember 2017 Analisis data menggunakan regresi berganda. Hasil penelitian ini menunjukkan bahwa, Persediaan Bahan Baku mempunyai pengaruh signifikan terhadap Proses Produksi, Pemeliharaan Peralatan tidak mempunyai Pengaruh signifikan terhadap Proses Produksi. Persediaan Bahan Baku dan Pemeliharaan Peralatan secara bersama-sama mempunyai pengaruh signifikan terhadap Proses Produksi. Kualitas produk sebagai variabel moderating tidak mempunyai pengaruh Persediaan Bahan Baku terhadap Proses Produksi dan Kualitas Produk sebagai variabel moderating tidak mampu memperkuat (memperlemah) Pemeliharaan Peralatan terhadap Proses Produksi

Nonporous Chitosan/Collagen Scaffold for Skin Tissue Engineering

This study aimed to determine film characteristics of chitosan/collagen scaffold for tissue engineering applications. Scaffold prepared using freeze drying method. Surface structure and biological testing chitosan/collagen scaffold crosslinking reagent addition Glutaraldehide studied using Scanning Electron Microscopy test (SEM) and Microscope inverted. Variations in the ratio of chitosan/collagen (10:0, 8:2, 7:3, 6:4, 5:5 4:6, 3:7, 2:8, 0:10), and treated with a crosslinking reagent 0.25% of Glutaraldehyde (GA) of the total weight of the polymer. The next process dissolving and mixing, followed by printing in glass moulds (7,5x7,5) with a thickness of 5 mm. This was followed by the freezing and drying with a freeze dryer. Scaffold chitosan/collagen ratio of 80:20 and a concentration of 0.25% GA showed growth of human skin fibroblast cells most and nonporous surface structure. This study is part of a study of the processing of chitosan/collagen scaffold for applications in tissue engineerin

Effects of random localizing events on matter waves: formalism and examples

A formalism is introduced to describe a number of physical processes that may break down the coherence of a matter wave over a characteristic length scale l. In a second-quantized description, an appropriate master equation for a set of bosonic "modes" (such as atoms in a lattice, in a tight-binding approximation) is derived. Two kinds of "localizing processes" are discussed in some detail and shown to lead to master equations of this general form: spontaneous emission (more precisely, light scattering), and modulation by external random potentials. Some of the dynamical consequences of these processes are considered: in particular, it is shown that they generically lead to a damping of the motion of the matter-wave currents, and may also cause a "flattening" of the density distribution of a trapped condensate at rest.Comment: v3; a few corrections, especially in Sections IV and