Quantum entanglement between a nonlinear nanomechanical resonator and a microwave field

We consider a theoretical model for a nonlinear nanomechanical resonator coupled to a superconducting microwave resonator. The nanomechanical resonator is driven parametrically at twice its resonance frequency, while the superconducting microwave resonator is driven with two tones that differ in frequency by an amount equal to the parametric driving frequency. We show that the semi-classical approximation of this system has an interesting fixed point bifurcation structure. In the semi-classical dynamics a transition from stable fixed points to limit cycles is observed as one moves from positive to negative detuning. We show that signatures of this bifurcation structure are also present in the full dissipative quantum system and further show that it leads to mixed state entanglement between the nanomechanical resonator and the microwave cavity in the dissipative quantum system that is a maximum close to the semi-classical bifurcation. Quantum signatures of the semi-classical limit-cycles are presented.Comment: 36 pages, 18 figure

The Casimir force on a surface with shallow nanoscale corrugations: Geometry and finite conductivity effects

We measure the Casimir force between a gold sphere and a silicon plate with nanoscale, rectangular corrugations with depth comparable to the separation between the surfaces. In the proximity force approximation (PFA), both the top and bottom surfaces of the corrugations contribute to the force, leading to a distance dependence that is distinct from a flat surface. The measured Casimir force is found to deviate from the PFA by up to 15%, in good agreement with calculations based on scattering theory that includes both geometry effects and the optical properties of the material

Optimal strategies for a game on amenable semigroups

The semigroup game is a two-person zero-sum game defined on a semigroup S as follows: Players 1 and 2 choose elements x and y in S, respectively, and player 1 receives a payoff f(xy) defined by a function f from S to [-1,1]. If the semigroup is amenable in the sense of Day and von Neumann, one can extend the set of classical strategies, namely countably additive probability measures on S, to include some finitely additive measures in a natural way. This extended game has a value and the players have optimal strategies. This theorem extends previous results for the multiplication game on a compact group or on the positive integers with a specific payoff. We also prove that the procedure of extending the set of allowed strategies preserves classical solutions: if a semigroup game has a classical solution, this solution solves also the extended game.Comment: 17 pages. To appear in International Journal of Game Theor

Neutron, electron and X-ray scattering investigation of Cr1-xVx near Quantum Criticality

The weakness of electron-electron correlations in the itinerant antiferromagnet Cr doped with V has long been considered the reason that neither new collective electronic states or even non Fermi liquid behaviour are observed when antiferromagnetism in Cr$_{1-x}$V$_{x}$ is suppressed to zero temperature. We present the results of neutron and electron diffraction measurements of several lightly doped single crystals of Cr$_{1-x}$V$_{x}$ in which the archtypal spin density wave instability is progressively suppressed as the V content increases, freeing the nesting-prone Fermi surface for a new striped charge instability that occurs at x$_{c}$=0.037. This novel nesting driven instability relieves the entropy accumulation associated with the suppression of the spin density wave and avoids the formation of a quantum critical point by stabilising a new type of charge order at temperatures in excess of 400 K. Restructuring of the Fermi surface near quantum critical points is a feature found in materials as diverse as heavy fermions, high temperature copper oxide superconductors and now even elemental metals such as Cr.Comment: 6 pages, 6 figures. Accepted to Physical Review

Prevalence of Noncardiac Findings in Patients Undergoing Cardiac Magnetic Resonance Imaging

Purpose. We sought to determine the prevalence of clinically significant non-cardiac abnormalities found in pediatric and adult patients undergoing cardiac magnetic resonance imaging (CMRI), and understand the impact of age on it's occurrence. Methods. We retrospectively reviewed all patients undergoing CMRI between May 2004 and July 2007. Findings were considered significant if they required radiographic or clinical follow-up. Results. A total of 408 patients underwent CMRI during the study period. Twenty two (16%) pediatric patients (age < 19 years, n = 135) were found to have a total of 22 non- cardiac abnormalities, 3 of which were clinically significant. Sixty four (23%) adult patients (age > 19 years, n = 273) were found to have a total of 77 non-cardiac abnormalities, 33 of which were clinically significant. The prevalence of clinically significant non-cardiac abnormalities was 2% in the pediatric cohort and 11% in the adult cohort (P = 0.05). Within the adult population, the prevalence of significant non-cardiac abnormalities increased with advancing age (P = 0.05). Conclusions. In a population of unselected patients undergoing CMRI, unanticipated noncardiac abnormalities were frequently seen. A small number of these were significant, with the prevalence increasing with age

Presidential Appointee Positions Requiring Senate Confirmation and Committees Handling Nominations

Report that identifies, by Senate committee, presidentially appointed positions requiring Senate confirmation based on referrals as of the date of passage of S. 679, which became P.L. 112-166 on August 10, 2012. It begins with a brief description of the referral process and identify, for each committee to which referrals have been made, the positions that fall within the committee's jurisdiction

Autoionization of the Ca 2 p

The decay of the photon-excited $2p^53s^23p^63d4s^2$ core resonances of atomic Ca has been studied by electron spectroscopy and by multiconfiguration calculations of the autoionization rates. Strong correlation effects give rise to complicated line structures that are mostly due to the autoionization of the resonances into the $3p^43d4s^2εl, 3p^43d4p^2εl$, and $3p^43d3εl$ continua. The breakdown of the spectator model, which is caused by the collapse of the 3d orbital, manifests itself in the dramatic differences between the spectra excited via the two resonances split by the spin-orbit and 2p-3d interactions

A novel, aerosol-nanocrystal floating-gate device for non-volatile memory applications

This paper describes the fabrication, and structural and electrical characterization of a new, aerosol-nanocrystal floating-gate FET, aimed at non-volatile memory (NVM) applications. This aerosol-nanocrystal NVM device features program/erase characteristics comparable to conventional stacked gate NVM devices, excellent endurance (>l0^5 P/E cycles), and long-term non-volatility in spite of a thin bottom oxide (55-60Å). In addition, a very simple fabrication process makes this aerosol-nanocrystal NVM device a potential candidate for low cost NVM applications