41 research outputs found
Ab initio study of the modification of elastic properties of alpha-iron by hydrostatic strain and by hydrogen interstitials
The effect of hydrostatic strain and of interstitial hydrogen on the elastic
properties of -iron is investigated using \textit{ab initio}
density-functional theory calculations. We find that the cubic elastic
constants and the polycrystalline elastic moduli to a good approximation
decrease linearly with increasing hydrogen concentration. This net strength
reduction can be partitioned into a strengthening electronic effect which is
overcome by a softening volumetric effect. The calculated hydrogen-dependent
elastic constants are used to determine the polycrystalline elastic moduli and
anisotropic elastic shear moduli. For the key slip planes in -iron,
and , we find a shear modulus reduction of
approximately 1.6% per at.% H.Comment: Updated first part of 1009.378
Multimode photon blockade
Interactions are essential for the creation of correlated quantum many-body
states. While two-body interactions underlie most natural phenomena, three- and
four-body interactions are important for the physics of nuclei [1], exotic
few-body states in ultracold quantum gases [2], the fractional quantum Hall
effect [3], quantum error correction [4], and holography [5, 6]. Recently, a
number of artificial quantum systems have emerged as simulators for many-body
physics, featuring the ability to engineer strong interactions. However, the
interactions in these systems have largely been limited to the two-body
paradigm, and require building up multi-body interactions by combining two-body
forces. Here, we demonstrate a pure N-body interaction between microwave
photons stored in an arbitrary number of electromagnetic modes of a multimode
cavity. The system is dressed such that there is collectively no interaction
until a target total photon number is reached across multiple distinct modes,
at which point they interact strongly. The microwave cavity features 9 modes
with photon lifetimes of ms coupled to a superconducting transmon
circuit, forming a multimode circuit QED system with single photon
cooperativities of . We generate multimode interactions by using
cavity photon number resolved drives on the transmon circuit to blockade any
multiphoton state with a chosen total photon number distributed across the
target modes. We harness the interaction for state preparation, preparing Fock
states of increasing photon number via quantum optimal control pulses acting
only on the cavity modes. We demonstrate multimode interactions by generating
entanglement purely with uniform cavity drives and multimode photon blockade,
and characterize the resulting two- and three-mode W states using a new
protocol for multimode Wigner tomography.Comment: 5 pages of main text with 5 figures. 11 pages of supplementary
information with 10 figure
Acylsucrose-Producing Tomato Plants Forces Bemisia tabaci to Shift Its Preferred Settling and Feeding Site
[Background] The whitefly Bemisia tabaci (Genn.) causes dramatic damage to plants by transmitting yield-limiting virus diseases. Previous studies proved that the tomato breeding line ABL 14-8 was resistant to B. tabaci, the vector of tomato yellow leaf curl disease (TYLCD). This resistance is based on the presence of type IV glandular trichomes and acylsucrose production. These trichomes deter settling and probing of B. tabaci in ABL 14-8, which reduces primary and secondary spread of TYLCD.[Methodology/Principal Findings] Whitefly settlement preference was evaluated on the adaxial and abaxial leaf surfaces of nearly-isogenic tomato lines with and without B. tabaci-resistance traits, 'ABL 14-8 and Moneymaker' respectively, under non-choice and free-choice conditions. In addition, the Electrical Penetration Graph technique was used to study probing and feeding activities of B. tabaci on the adaxial and abaxial leaf surfaces of the same genotypes. B. tabaci preferred to settle on the abaxial than on the adaxial surface of 'Moneymaker' leaves, whereas no such preference was observed on ABL 14-8 tomato plants at the ten-leaf growth stage. Furthermore, B. tabaci preferred to feed on the abaxial than on the adaxial leaf surface of 'Moneymarker' susceptible tomato plants as shown by a higher number of sustained phloem feeding ingestion events and a shorter time to reach the phloem. However, B. tabaci standard probing and feeding behavior patterns were altered in ABL 14-8 plants and whiteflies were unable to feed from the phloem and spent more time in non-probing activities when exposed to the abaxial leaf surface.[Conclusions/Significance] The distorted behavior of B. tabaci on ABL 14-8 protects tomato plants from the transmission of phloem-restricted viruses such as Tomato yellow leaf curl virus (TYLCV), and forces whiteflies to feed on the adaxial side of leaves where they feed less efficiently and become more vulnerable to natural enemies. © 2012 Rodriguez-Lopez et al.Ministerio de Ciencia e Innovación Spain (co-financed by FEDER) projects: AGL2007-66760-C02-02/AGR, AGL2007-66399-CO3-02/AGR, and AGL2010-22287-C02-01/AGR, AGL2010-22287-C02-01/AGR ConsejerÃa de Innovación y Ciencia, Junta de AndalucÃa, Spain (co-financed by FEDER-FSE) projects: AGR-214 and AGR-129Peer Reviewe
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Multimode photon blockade
Interactions are essential for the creation of correlated quantum many-body states. Although two-body interactions underlie most natural phenomena, three- and four-body interactions are important for the physics of nuclei1, exotic few-body states in ultracold quantum gases2, the fractional quantum Hall effect3, quantum error correction4 and holography5,6. Recently, a number of artificial quantum systems have emerged as simulators for many-body physics, featuring the ability to engineer strong interactions. However, the interactions in these systems have largely been limited to the two-body paradigm and require building up multibody interactions by combining two-body forces. Here we implement a scheme to create a higher-order interaction between photons stored in multiple electromagnetic modes of a microwave cavity. The system is dressed such that there is collectively no interaction until a target total photon number is reached across multiple distinct modes, at which point the photons interact strongly. In our demonstration, we create interactions involving up to three bodies and across up to five modes. We harness the interaction to prepare single-mode Fock states and multimode W states, which we verify by introducing a multimode Wigner tomography method