Fast nonadiabatic two-qubit gates for the Kane quantum computer

In this paper, we apply the canonical decomposition of two-qubit unitaries to find pulse schemes to control the proposed Kane quantum computer. We explicitly find pulse sequences for the controlled-NOT, swap, square root of swap, and controlled Z rotations. We analyze the speed and fidelity of these gates, both of which compare favorably to existing schemes. The pulse sequences presented in this paper are theoretically faster, with higher fidelity, and simpler. Any two-qubit gate may be easily found and implemented using similar pulse sequences. Numerical simulation is used to verify the accuracy of each pulse scheme.

The effects of J-gate potential and interfaces on donor exchange coupling in the Kane quantum computer architecture

We calculate the electron exchange coupling for a phosphorus donor pair in silicon perturbed by a J-gate potential and the boundary effects of the silicon host geometry. In addition to the electron-electron exchange interaction we also calculate the contact hyperfine interaction between the donor nucleus and electron as a function of the varying experimental conditions. Donor separation, depth of the P nuclei below the silicon oxide layer and J-gate voltage become decisive factors in determining the strength of both the exchange coupling and hyperfine interaction-both crucial components for qubit operations in the Kane quantum computer. These calculations were performed using an anisotropic effective-mass Hamiltonian approach. The behaviour of the donor exchange coupling as a function of the parameters varied in this work provides relevant information for the experimental design of these devices.

Gates for the kane quantum computer in the presence of dephasing

In this paper we investigate the effect of dephasing on proposed quantum gates for the solid-state Kane quantum computing architecture. Using a simple model of the decoherence, we find that the typical error in a controlled-NOT gate is 8.3x10(-5). We also compute the fidelities of Z, X, swap, and controlled Z operations under a variety of dephasing rates. We show that these numerical results are comparable with the error threshold required for fault tolerant quantum computation.

Endangered ancestress revisited: Sarah's miraculous motherhood and the restoration of Eden

The paper examines the ‘endangered ancestress’ theme in Genesis, in which the matriarchs, Sarah and Rebecca, are passed off to alien rulers as the sisters of their respective husbands, in Sarah’s case twice. Rather than viewing these incidents as clumsy duplication, the paper reads them as a literary device in a continuous narrative. The paper argues that when read in this way, these incidents serve to underline the singular status of Sarah in contrast to Rebecca and subsequent matriarchs. Sarah is shown to be the unique foremother of Israel. Alone of all her sex, she represents a pristine new beginning, analogous to human beginnings in Eden.

The Seduction of Sarah: travel memoirs and intercultural learning

The paper explores the nexus between intercultural storytelling and intercultural learning. Noting the wide appeal of the travel memoir set in France, it takes as a case study a book that, while positioned within that genre, attempts to shift some predictable patterns: Sarah Turnbull’s best-selling Almost French. Analysis shows that the book in fact participates in a subtle play of genres, whereby the lure of the travel memoir is used to entice readers towards a position where they read the book as a guide to French culture. The particular form of hybridity attempted is, however, a delicate enterprise, as the reception of the book demonstrates, in that the intercultural lessons on offer risk being overshadowed by the expectations readers bring to the genre of the travel memoir. The paper examines the competing seductions operating throughout the text and relates the conditions for taking up the opportunity for intercultural learning to questions of genre. It offers a pedagogical uptake of the textual analysis, thus bridging disciplines in a way that mirrors Turnbull’s bridging of genres