Design space for low sensitivity to size variations in [110] PMOS nanowire devices: The implications of anisotropy in the quantization mass

A 20-band sp3d5s* spin-orbit-coupled, semi-empirical, atomistic tight-binding model is used with a semi-classical, ballistic, field-effect-transistor (FET) model, to examine the ON-current variations to size variations of [110] oriented PMOS nanowire devices. Infinitely long, uniform, rectangular nanowires of side dimensions from 3nm to 12nm are examined and significantly different behavior in width vs. height variations are identified and explained. Design regions are identified, which show minor ON-current variations to significant width variations that might occur due to lack of line width control. Regions which show large ON-current variations to small height variations are also identified. The considerations of the full band model here show that ON-current doubling can be observed in the ON-state at the onset of volume inversion to surface inversion transport caused by structural side size variations. Strain engineering can smooth out or tune such sensitivities to size variations. The cause of variations described is the structural quantization behavior of the nanowires, which provide an additional variation mechanism to any other ON-current variations such as surface roughness, phonon scattering etc.Comment: 24 pages, 5 figure

Minding our ps and qs: Issues of property, provenance, quantity and quality in institutional repositories

The development of institutional repositories has opened the path to the mass availability of peer-reviewed scholarly information and the extension of information democracy to the academic domain. A secondary space of free-to-all documents has begun to parallel the hitherto-closed world of journal publishing and many publishers have consented to the inclusion of copyrighted documents in digital repositories, although frequently specifying that a version other than the formally-published one be used. This paper will conceptually examine the complex interplay of rights, permissions and versions between publishers and repositories, focussing on the New Zealand situation and the challenges faced by university repositories in recruiting high-quality peer-reviewed documents for the open access domain. A brief statistical snapshot of the appearance of material from significant publishers in repositories will be used to gauge the progress that has been made towards broadening information availability. The paper will also look at the importance of harvesting and dissemination, in particular the role of Google Scholar in bringing research information within reach of ordinary internet users. The importance of accuracy, authority, provenance and transparency in the presentation of research-based information and the important role that librarians can and should play in optimising the open research discovery experience will be emphasised

Persistence of entanglement in thermal states of spin systems

We study and compare the persistence of bipartite entanglement (BE) and multipartite entanglement (ME) in one-dimensional and two-dimensional spin XY models in an external transverse magnetic field under the effect of thermal excitations. We compare the threshold temperature at which the entanglement vanishes in both types of entanglement. We use the entanglement of formation as a measure of the BE and the geometric measure to evaluate the ME of the system. We have found that in both dimensions in the anisotropic and partially anisotropic spin systems at zero temperatures, all types of entanglement decay as the magnetic field increases but are sustained with very small magnitudes at high field values. Also we found that for the same systems, the threshold temperatures of the nearest neighbour (nn) BEs are higher than both of the next-to-nearest neighbour BEs and MEs and the three of them increase monotonically with the magnetic field strength. Thus, as the temperature increases, the ME and the far parts BE of the system become more fragile to thermal excitations compared to the nn BE. For the isotropic system, all types of entanglement and threshold temperatures vanish at the same exact small value of the magnetic field. We emphasise the major role played by both the properties of the ground state of the system and the energy gap in controlling the characteristics of the entanglement and threshold temperatures. In addition, we have shown how an inserted magnetic impurity can be used to preserve all types of entanglement and enhance their threshold temperatures. Furthermore, we found that the quantum effects in the spin systems can be maintained at high temperatures, as the different types of entanglements in the spin lattices are sustained at high temperatures by applying sufficiently high magnetic fields.Comment: 20 pages, 17 figure

Chapter 6: Federal Compliance

IPFW\u27s institutional self-study in preparation for the 2010 accreditation visit of The Higher Learning Commission of The North Central Association of Colleges and Schools

Practical speed meter designs for quantum nondemolition gravitational-wave interferometers

In the quest to develop viable designs for third-generation optical interferometric gravitational-wave detectors (e.g., LIGO-III and EURO), one strategy is to monitor the relative momentum or speed of the test-mass mirrors, rather than monitoring their relative position. A previous paper analyzed a straightforward but impractical design for a speed-meter interferometer that accomplishes this. This paper describes some practical variants of speed-meter interferometers. Like the original interferometric speed meter, these designs in principle can beat the gravitational-wave standard quantum limit (SQL) by an arbitrarily large amount, over an arbitrarily wide range of frequencies. These variants essentially consist of a Michelson interferometer plus an extra ``sloshing'' cavity that sends the signal back into the interferometer with opposite phase shift, thereby cancelling the position information and leaving a net phase shift proportional to the relative velocity. In practice, the sensitivity of these variants will be limited by the maximum light power W-circ circulating in the arm cavities that the mirrors can support and by the leakage of vacuum into the optical train at dissipation points. In the absence of dissipation and with squeezed vacuum (power squeeze factor e(-2R)similar or equal to0.1) inserted into the output port so as to keep the circulating power down, the SQL can be beat by h/h(SQL)similar torootW(circ)(SQL)e(-2R)/W-circ at all frequencies below some chosen f(opt)similar or equal to100 Hz. Here W(circ)(SQL)similar or equal to800 kW(f(opt)/100 Hz)(3) is the power required to reach the SQL in the absence of squeezing. (However, as the power increases in this expression, the speed meter becomes more narrow band; additional power and reoptimization of some parameters are required to maintain the wide band. See Sec. III B.) Estimates are given of the amount by which vacuum leakage at dissipation points will debilitate this sensitivity (see Fig. 12); these losses are 10% or less over most of the frequency range of interest (fgreater than or similar to10 Hz). The sensitivity can be improved, particularly at high freqencies, by using frequency-dependent homodyne detection, which unfortunately requires two 4-km-long filter cavities (see Fig. 4)