4,232 research outputs found
Blackbox Quantization of Superconducting Circuits using exact Impedance Synthesis
We propose a new quantization method for superconducting electronic circuits
involving a Josephson junction device coupled to a linear microwave
environment. The method is based on an exact impedance synthesis of the
microwave environment considered as a blackbox with impedance function Z(s).
The synthesized circuit captures dissipative dynamics of the system with
resistors coupled to the reactive part of the circuit in a non-trivial way. We
quantize the circuit and compute relaxation rates following previous formalisms
for lumped element circuit quantization. Up to the errors in the fit our method
gives an exact description of the system and its losses
Magnonic spin-transfer torque MRAM with low power, high speed, and error-free switching
A new class of spin-transfer torque magnetic random access memory (STT-MRAM)
is discussed, in which writing is achieved using thermally initiated magnonic
current pulses as an alternative to conventional electric current pulses. The
magnonic pulses are used to destabilize the magnetic free layer from its
initial direction, and are followed immediately by a bipolar electric current
exerting conventional spin-transfer torque on the free layer. The combination
of thermal and electric currents greatly reduces switching errors, and
simultaneously reduces the electric switching current density by more than an
order of magnitude as compared to conventional STT-MRAM. The energy efficiency
of several possible electro-thermal circuit designs have been analyzed
numerically. As compared to STT-MRAM with perpendicular magnetic anisotropy,
magnonic STT-MRAM reduces the overall switching energy by almost 80%.
Furthermore, the lower electric current density allows the use of thicker
tunnel barriers, which should result in higher tunneling magneto-resistance and
improved tunnel barrier reliability. The combination of lower power, improved
reliability, higher integration density, and larger read margin make magnonic
STT-MRAM a promising choice for future non-volatile storage.Comment: 9 Pages, 11 Figure
Noise reduction technique for scanning tunneling microscopy
Journal ArticleNoise stemming from mechanical vibration, electronic noise, or low frequency (l / f power spectrum) inherent in the tunneling process, often limits the resolution, speed, or range of application of scanning tunneling microscopy (STM). We demonstrate a technique for minimizing the effect of these noise sources on the STM image
Measurement of in-plane magnetization by force microscopy
Journal ArticleWe present data which show that the magnetic force microscope is capable of detecting the component of the magnetic field parallel to the surface of a sample under study. Images of bits in a Co-alloy thin-film disk and of laser-written bits in a TbFe film were taken with a magnetized tip tilted at 45° with respect to the surface normal. In both cases the asymmetric part of the image of a domain is interpreted in terms of gradients in the in-plane component of the magnetic field. The bits written in the Co-alloy disk were decorated with small magnetized particles, allowing identification of the domain boundaries and the asymmetric component of the force microscope image due to in-plane magnetization
Two algorithms for the student-project allocation problem
We study the Student-Project Allocation problem (SPA), a generalisation of the classical Hospitals / Residents problem (HR). An instance of SPA involves a set of students, projects and lecturers. Each project is offered by a unique lecturer, and both projects and lecturers have capacity constraints. Students have preferences over projects, whilst lecturers have preferences over students. We present two optimal linear-time algorithms for allocating students to projects, subject to the preference and capacity constraints. In particular, each algorithm finds a stable matching of students to projects. Here, the concept of stability generalises the stability definition in the HR context. The stable matching produced by the first algorithm is simultaneously best-possible for all students, whilst the one produced by the second algorithm is simultaneously best-possible for all lecturers. We also prove some structural results concerning the set of stable matchings in a given instance of SPA. The SPA problem model that we consider is very general and has applications to a range of different contexts besides student-project allocation
The Effects of High Intensity Interval Training (HIIT) on Insulin Sensitivity in Individuals with a Family History of Type 2 DIABETES
Supertubes
It is shown that a IIA superstring carrying D0-brane charge can be
`blown-up', in a {\it Minkowski vacuum} background, to a (1/4)-supersymmetric
tubular D2-brane, supported against collapse by the angular momentum generated
by crossed electric and magnetic Born-Infeld fields. This `supertube' can be
viewed as a worldvolume realization of the sigma-model Q-lump.Comment: Revision includes mention of some configurations dual to the
supertub
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