Cross correlations in mesoscopic charge detection

We study a tunnel contact that acts as charge detector for a single-electron transistor (SET) focusing on correlations between the detector current and the current through the SET. This system can be described fully by a Markovian master equation for the SET, while electron tunneling in the charge monitor represents a process with a stochastic rate, which can be solved exactly. It turns out that current monitoring is possible as long as the detector current correlates with the currents through either SET barrier. By contrast, correlations with the effective current according to the Ramo-Shockley theorem are not essential. Moreover, we propose the measurement of the SET barrier capacitances.Comment: 7 pages, 2 figure

This Town Ain’t Big Enough for the Both of Us—Or Is It? Reflections on Copyright, the First Amendment and Google’s Use of Others’ Content

Using a variety of technological innovations, Google became a multi-billion dollar content-delivery business without owning or licensing much of the content that it uses. Google’s principal justification for why this strategy does not contravene the intellectual property rights of the copyright owners is the doctrine of fair use. However, over the last several years, some copyright owners began to push back and challenge Google’s strategy. Much of this litigation presents the courts with something of a conundrum. On the one hand, it is beyond dispute that Google’s services have great social utility. By organizing and making accessible an enormous volume of information on the Internet, Google facilitates broad access to a diverse array of material, a core value of the First Amendment. At the same time, Google’s actions do not always fit comfortably within traditional notions of fair use. In this respect, the Google cases present an opportunity to explore the relationship between copyright and the First Amendment; a subject that has received inadequate attention in the courts, and particularly the Supreme Court. How the apparent tension between the marketplace of ideas and the commercial marketplace is resolved may have significant impact on the development of Internet-based services designed to facilitate access to information, and this subject is the focus of this iBrief

Minimal coupling in oscillator models of quantum dissipation

The dissipative harmonic oscillator has two representations. In the first representation the central oscillator couples with its position to an oscillator bath. In the second one it couples with its momentum to the bath. Both representations are related by a unitary transformation. If the central oscillator couples with its position and momentum to two independent baths, no such unitary transformation exists. We discuss two possible models of this type and their physical relevance