17,565 research outputs found
Laying Down the Foundations for International Student Journey. Students as Academic Partners Project Report.
The aim of this project was to explore the lived experiences of being an international student studying at a University within the UK and to make recommendations for future provision. There are increasing numbers of international students studying at Universities within the UK. Positive learning environments and arrangements are the responsibility of the host University and international students’ needs should be taken into consideration. This project was led by international students in collaboration with academic staff. It involved a qualitative exploration of international student perspectives and their experiences of studying within the UK. Ten international students completed a questionnaire that was designed by international students. Respondents were asked questions in relation to three areas: coming to the UK, arriving in the UK and studying in the UK
Factoring in a Dissipative Quantum Computer
We describe an array of quantum gates implementing Shor's algorithm for prime
factorization in a quantum computer. The array includes a circuit for modular
exponentiation with several subcomponents (such as controlled multipliers,
adders, etc) which are described in terms of elementary Toffoli gates. We
present a simple analysis of the impact of losses and decoherence on the
performance of this quantum factoring circuit. For that purpose, we simulate a
quantum computer which is running the program to factor N = 15 while
interacting with a dissipative environment. As a consequence of this
interaction randomly selected qubits may spontaneously decay. Using the results
of our numerical simulations we analyze the efficiency of some simple error
correction techniques.Comment: plain tex, 18 pages, 8 postscript figure
Indeterminate-length quantum coding
The quantum analogues of classical variable-length codes are
indeterminate-length quantum codes, in which codewords may exist in
superpositions of different lengths. This paper explores some of their
properties. The length observable for such codes is governed by a quantum
version of the Kraft-McMillan inequality. Indeterminate-length quantum codes
also provide an alternate approach to quantum data compression.Comment: 32 page
Judging the impact of leadership-development activities on school practice
The nature and effectiveness of professional-development activities should be judged in a way that takes account of
both the achievement of intended outcomes and the unintended consequences that may result. Our research project set out to create a robust approach that school staff members could use to assess the impact of
professional-development programs on leadership and management practice without being constrained in this judgment by the stated aims of the program. In the process,
we identified a number of factors and requirements relevant to a wider audience than that concerned with the development of leadership and management in England.
Such an assessment has to rest upon a clear understanding of educational leadership,a clearly articulated model of practice, and a clear model of potential forms of impact.
Such foundations, suitably adapted to the subject being addressed, are appropriate for assessing all teacher professional development
Spatially resolved spectroscopy of monolayer graphene on SiO2
We have carried out scanning tunneling spectroscopy measurements on
exfoliated monolayer graphene on SiO to probe the correlation between its
electronic and structural properties. Maps of the local density of states are
characterized by electron and hole puddles that arise due to long range
intravalley scattering from intrinsic ripples in graphene and random charged
impurities. At low energy, we observe short range intervalley scattering which
we attribute to lattice defects. Our results demonstrate that the electronic
properties of graphene are influenced by intrinsic ripples, defects and the
underlying SiO substrate.Comment: 6 pages, 7 figures, extended versio
Purifying two-bit quantum gates and joint measurements in cavity QED
Using a cavity QED setup we show how to implement a particular joint
measurement on two atoms in a fault tolerant way. Based on this scheme, we
illustrate how to realize quantum communication over a noisy channel when local
operations are subject to errors. We also present a scheme to perform and
purify a universal two-bit gate.Comment: 4 pages RevTeX, 2 figures include
On the origin of ambiguity in efficient communication
This article studies the emergence of ambiguity in communication through the
concept of logical irreversibility and within the framework of Shannon's
information theory. This leads us to a precise and general expression of the
intuition behind Zipf's vocabulary balance in terms of a symmetry equation
between the complexities of the coding and the decoding processes that imposes
an unavoidable amount of logical uncertainty in natural communication.
Accordingly, the emergence of irreversible computations is required if the
complexities of the coding and the decoding processes are balanced in a
symmetric scenario, which means that the emergence of ambiguous codes is a
necessary condition for natural communication to succeed.Comment: 28 pages, 2 figure
Quantum Cryptography using larger alphabets
Like all of quantum information theory, quantum cryptography is traditionally
based on two level quantum systems. In this letter, a new protocol for quantum
key distribution based on higher dimensional systems is presented. An
experimental realization using an interferometric setup is also proposed.
Analyzing this protocol from the practical side, one finds an increased key
creation rate while keeping the initial laser pulse rate constant. Analyzing it
for the case of intercept/resend eavesdropping strategy, an increased error
rate is found compared to two dimensional systems, hence an advantage for the
legitimate users to detect an eavesdropper.Comment: 12 pages, 2 (eps) figure
Robust long-distance entanglement and a loophole-free Bell test with ions and photons
Two trapped ions that are kilometers apart can be entangled by the joint
detection of two photons, each coming from one of the ions, in a basis of
entangled states. Such a detection is possible with linear optical elements.
The use of two-photon interference allows entanglement distribution without
interferometric sensitivity to the path length of the photons. The present
method of creating entangled ions also opens up the possibility of a
loophole-free test of Bell's inequalities.Comment: published versio
Quantum Cryptography with Coherent States
The safety of a quantum key distribution system relies on the fact that any
eavesdropping attempt on the quantum channel creates errors in the
transmission. For a given error rate, the amount of information that may have
leaked to the eavesdropper depends on both the particular system and the
eavesdropping strategy. In this work, we discuss quantum cryptographic
protocols based on the transmission of weak coherent states and present a new
system, based on a symbiosis of two existing ones, and for which the
information available to the eavesdropper is significantly reduced. This system
is therefore safer than the two previous ones. We also suggest a possible
experimental implementation.Comment: 20 pp. Revtex, Figures available from the authors upon request, To be
published in PRA (March 95
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