3,726 research outputs found
UWB microstrip filter design using a time-domain technique
A time-domain technique is proposed for ultra-wideband (UWB) microstrip-filter design. The design technique uses the reflection coefficient (S11) specified in the frequency domain. When the frequency response of the UWB filter is given, the response will be approximated by a series of UWB pulses in the time domain. The UWB pulses are Gaussian pulses of the same bandwidth with different time delays. The method tries to duplicate the reflection scenario in the time domain for very narrow Gaussian pulses (to obtain the impulse response of the system) when the pulses are passed through the filter, and obtains the value of the filter coefficients based on the number of UWB pulses, amplitudes, and delays of the pulses
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The Maine Wabanaki-State Child Welfare Truth and Reconciliation Commission: Perceptions and Understandings
As this chapter demonstrates, the MWTRC represents a unique and creative approach to healing in communities affected by historical trauma. This chapter presents the history and context of the MWTRC. Drawing on interviews with the key participants4 in the MWTRC creation process, we explain the structure, mandate and role of the MWTRC and the accompanying community support structures that have been created. Key themes emerging from the interviews with the participants in the process are then discussed. The chapter shows that, originating in a deep understanding of the complex individual, family and community trauma that Wabanaki people have endured, the MWTRC embodies a collective desire for truth, healing and change. It provides a space for the articulation of a silenced history, and a process within which traumatic experiences and the trauma of memory can be shared in solidarity. The uniqueness of the MWTRCâa grassroots, community-organized, Indigenous community-state collaborationâ makes it an important process for scholars and practitioners to follow. Although it faces challenges and tensions and involves difficult dialogues on race, privilege and accountability, this MWTRC is a new kind of truth commission, linking reconciliation with decolonization, and truth with practical policy change, in the process creating an important model of community-based conflict transformation and trauma recovery that has potentially wider implications for other communitiesâIndigenous, and non-Indigenousâseeking to reconcile, and to heal, after a period of long-term trauma. To see why such healing is truly necessary, this chapter turns to a summary of the historical context of trauma that the MWTRC aims to address
Demonstration of Entanglement of Electrostatically Coupled Singlet-Triplet Qubits
Quantum computers have the potential to solve certain interesting problems
significantly faster than classical computers. To exploit the power of a
quantum computation it is necessary to perform inter-qubit operations and
generate entangled states. Spin qubits are a promising candidate for
implementing a quantum processor due to their potential for scalability and
miniaturization. However, their weak interactions with the environment, which
leads to their long coherence times, makes inter-qubit operations challenging.
We perform a controlled two-qubit operation between singlet-triplet qubits
using a dynamically decoupled sequence that maintains the two-qubit coupling
while decoupling each qubit from its fluctuating environment. Using state
tomography we measure the full density matrix of the system and determine the
concurrence and the fidelity of the generated state, providing proof of
entanglement
Quantum Clock Synchronization Based on Shared Prior Entanglement
We demonstrate that two spatially separated parties (Alice and Bob) can
utilize shared prior quantum entanglement, and classical communications, to
establish a synchronized pair of atomic clocks. In contrast to classical
synchronization schemes, the accuracy of our protocol is independent of Alice
or Bob's knowledge of their relative locations or of the properties of the
intervening medium.Comment: 4 page
'Lad culture' in higher education: agency in the sexualisation debates
This paper reports on research funded by the National Union of Students, which explored women studentsâ experiences of âlad cultureâ through focus groups and interviews. We found that although laddism is only one of various potential masculinities, for our participants it dominated social and sexual spheres of university life in problematic ways. However, their objections to laddish behaviours did not support contemporary models of âsexual panicâ, even while oppugning the more simplistic celebrations of young womenâs empowerment which have been observed in debates about sexualisation. We argue that in their ability to reject âlad cultureâ, our respondents expressed a form of agency which is often invisibilised in sexualisation discussions and which could be harnessed to tackle some of the issues we uncovered
Spin decay and quantum parallelism
We study the time evolution of a single spin coupled inhomogeneously to a
spin environment. Such a system is realized by a single electron spin bound in
a semiconductor nanostructure and interacting with surrounding nuclear spins.
We find striking dependencies on the type of the initial state of the nuclear
spin system. Simple product states show a profoundly different behavior than
randomly correlated states whose time evolution provides an illustrative
example of quantum parallelism and entanglement in a decoherence phenomenon.Comment: 6 pages, 4 figures included, version to appear in Phys. Rev.
Spin swap gate in the presence of qubit inhomogeneity in a double quantum dot
We study theoretically the effects of qubit inhomogeneity on the quantum
logic gate of qubit swap, which is an integral part of the operations of a
quantum computer. Our focus here is to construct a robust pulse sequence for
swap operation in the simultaneous presence of Zeeman inhomogeneity for quantum
dot trapped electron spins and the finite-time ramp-up of exchange coupling in
a double dot. We first present a geometric explanation of spin swap operation,
mapping the two-qubit operation onto a single-qubit rotation. We then show that
in this geometric picture a square-pulse-sequence can be easily designed to
perform swap in the presence of Zeeman inhomogeneity. Finally, we investigate
how finite ramp-up times for the exchange coupling negatively affect the
performance of the swap gate sequence, and show how to correct the problems
numerically.Comment: published versio
Quantum Information Processing with Ferroelectrically Coupled Quantum Dots
I describe a proposal to construct a quantum information processor using
ferroelectrically coupled Ge/Si quantum dots. The spin of single electrons form
the fundamental qubits. Small (<10 nm diameter) Ge quantum dots are optically
excited to create spin polarized electrons in Si. The static polarization of an
epitaxial ferroelectric thin film confines electrons laterally in the
semiconductor; spin interactions between nearest neighbor electrons are
mediated by the nonlinear process of optical rectification. Single qubit
operations are achieved through "g-factor engineering" in the Ge/Si structures;
spin-spin interactions occur through Heisenberg exchange, controlled by
ferroelectric gates. A method for reading out the final state, while required
for quantum computing, is not described; electronic approaches involving single
electron transistors may prove fruitful in satisfying this requirement.Comment: 10 pages, 3 figure
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