Radio-frequency magnetometry using a single electron spin

We experimentally demonstrate a simple and robust protocol for the detection of weak radio-frequency magnetic fields using a single electron spin in diamond. Our method relies on spin locking, where the Rabi frequency of the spin is adjusted to match the MHz signal frequency. In a proof-of-principle experiment we detect a 7.5 MHz magnetic probe field of 40 nT amplitude with <10 kHz spectral resolution over a T_1-limited noise floor of 0.3 nT/rtHz. Rotating-frame magnetometry may provide a direct and sensitive route to high-resolution spectroscopy of nanoscale nuclear spin signals

Spurious harmonic response of multipulse quantum sensing sequences

Multipulse sequences based on Carr-Purcell decoupling are frequently used for narrow-band signal detection in single spin magnetometry. We have analyzed the behavior of multipulse sensing sequences under real-world conditions, including finite pulse durations and the presence of detunings. We find that these non-idealities introduce harmonics to the filter function, allowing additional frequencies to pass the filter. In particular, we find that the XY family of sequences can generate signals at the 2fac, 4fac and 8fac harmonics and their odd subharmonics, where fac is the ac signal frequency. Consideration of the harmonic response is especially important for diamond-based nuclear spin sensing where the NMR frequency is used to identify the nuclear spin species, as it leads to ambiguities when several isotopes are present.Comment: 6 pages, 7 figure

Quaternary evolution of the lower calore and middle volturno valleys (Southern Italy)

The lower Calore and middle Volturno valleys preserve stratigraphical and morphological evidence and tephrostratigraphic markers particularly suitable for reconstructing the long-term geomorphological evolution of the central-southern Apennines. Aim of our study is to identify the main steps of the Quaternary landscape evolution of these valley systems and to improve knowledge about the relationships between fluvial processes and tectonics, volcanic activity, climatic and human influences. To this purpose, we carried out an integrated geomorphological and chronostratigraphical analysis of identified fluvial landforms and related deposits, integrated by230Th/234U datings on travertines from the Telese Plain area. The study highlighted in particular: (1) fluvial sedimentation started in the Middle Pleistocene (~650 ka) within valleys that originated in the lower Pleistocene under the control of high-angle faults; (2) extensional tectonics acted during the Middle and Upper Pleistocene, driving the formation of the oldest fluvial terraces and alluvial fans, and persisted beyond the emplacement of the Campanian Ignimbrite pyroclastic deposits (~39 ka); and (3) from the late Upper Pleistocene onwards (&lt;15 ka), the role of tectonics appears negligible, while climatic changes played a key role in the formation of three orders of valley floor terraces and the youngest alluvial fans

Quad 14Gbps L-Band VCSEL-based System for WDM Migration of 4-lanes 56 Gbps Optical Data Links

We report on migrating multiple-lane link into an L-band VCSEL-based WDM system. Experimental validation achieves successful transmission over 10 km of SMF at 4x14Gbps. Inter-channel crosstalk penalty is observed to be less than 0.5 dB and a transmission penalty around 1 dB. The power budget margin ranges within 6 dB and 7 dB

Investigation of Surface Magnetic Noise by Shallow Spins in Diamond

We present measurements of spin relaxation times (T1, T1ρ, T2) on very shallow (≲5  nm) nitrogen-vacancy centers in high-purity diamond single crystals. We find a reduction of spin relaxation times up to 30 times compared to bulk values, indicating the presence of ubiquitous magnetic impurities associated with the surface. Our measurements yield a density of 0.01–0.1μB/nm2 and a characteristic correlation time of 0.28(3) ns of surface states, with little variation between samples and chemical surface terminations. A low temperature measurement further confirms that fluctuations are thermally activated. The data support the atomistic picture where impurities are associated with the top carbon layers, and not with terminating surface atoms or adsorbate molecules. The low spin density implies that the presence of A single surface impurity is sufficient to cause spin relaxation of a shallow nitrogen-vacancy center

Clasificación visual de madera estructural de pino laricio (Pinus nigra Arn.): comparación de resultados usando las normas UNE 56.544 y DIN 4074

On a 776 boards sample of Pinus nigra 150 X 50 X 3.000 mm size, coming from felled trees in Jaen (Spain) a comparison of results is made using two different standards of visual strength grading, the German DIN 4074, usually employed within Europe, and the recent Spanish UNE 56544. Graded the same batch of timber by means of both standards, the yields and the physico-mechanical properties of every grade are calculated. The physico-mechanical properties of timber (density, bending strength and modulus of elasticity) are studied by testing according to the methodology included in the European standard EN 408, calculating the results according to the standard EN 384 and assigning the strength classes according to EN 338. The results lead to the conclusion that the use of the Spanish standard produces almost the same results than the use of the German standard, not only as far as the yields are concerned but also regarding the physico-mechanical properties of timber. In this way a second conclusion is reached, the Spanish standard follows criteria and produces results commonly accepted by the market.Sobre una muestra de 776 tablones de Pinus nigra Arn. de dimensiones 150 X 50 X 3.000 mm, procedentes todos ellos de &aacute;rboles cortados en Ja&eacute;n (Espa&ntilde;a), se efect&uacute;a una comparaci&oacute;n de resultados empleando dos normas de clasificaci&oacute;n visual de la madera aserrada con destino estructural, la norma alemana DIN 4074, habitualmente empleada en el seno de Europa y la norma espa&ntilde;ola, de muy reciente introducci&oacute;n, la UNE 56.544. Clasificado el mismo lote de madera por ambas normas, se determinan los rendimientos clasificatorios y las caracter&iacute;sticas f&iacute;sico-mec&aacute;nicas de la madera agrupada en cada clase de calidad La determinaci&oacute;n de las propiedades f&iacute;sico-mec&aacute;nicas de la madera (densidad, Resistencia a la flexi&oacute;n y M&oacute;dulo de elasticidad) se efect&uacute;a haciendo uso de la metodolog&iacute;a contenida en la norma europea EN 408, calculando los valores de resistencia seg&uacute;n la norma EN 384 y asignando las clases de resistencia seg&uacute;n lo establecido en la norma EN 338. Los resultados habidos reflejan que el uso de la norma espa&ntilde;ola lleva a resultados similares a los de la norma alemana, tanto en rendimientos como en resistencia, motivo por lo cual se considera que la susodicha norma espa&ntilde;ola sigue unos criterios aceptados y muy arraigados en el mercado