Integrating all-optical switching with spintronics

All-optical switching (AOS) of magnetic materials describes the reversal of the magnetization using short (femtosecond) laser pulses, and has been observed in a variety of materials. In the past decade it received extensive attention due to its high potential for fast and energy-efficient data writing in future spintronic memory applications. Unfortunately, the AOS mechanism in the ferromagnetic multilayers commonly used in spintronics needs multiple pulses for the magnetization reversal, losing its speed and energy efficiency. Here, we experimentally demonstrate `on-the-fly' single-pulse AOS in combination with spin Hall effect (SHE) driven motion of magnetic domains in Pt/Co/Gd synthetic-ferrimagnetic racetracks. Moreover, using field-driven-SHE-assisted domain wall (DW) motion measurements, both the SHE efficiency in the racetrack is determined and the chirality of the optically written DW's is verified. Our experiments demonstrate that Pt/Co/Gd racetracks facilitate both single-pulse AOS as well as efficient SHE induced domain wall motion, which might ultimately pave the way towards integrated photonic memory devices

Classical Optimizers for Noisy Intermediate-Scale Quantum Devices

We present a collection of optimizers tuned for usage on Noisy Intermediate-Scale Quantum (NISQ) devices. Optimizers have a range of applications in quantum computing, including the Variational Quantum Eigensolver (VQE) and Quantum Approximate Optimization (QAOA) algorithms. They are also used for calibration tasks, hyperparameter tuning, in machine learning, etc. We analyze the efficiency and effectiveness of different optimizers in a VQE case study. VQE is a hybrid algorithm, with a classical minimizer step driving the next evaluation on the quantum processor. While most results to date concentrated on tuning the quantum VQE circuit, we show that, in the presence of quantum noise, the classical minimizer step needs to be carefully chosen to obtain correct results. We explore state-of-the-art gradient-free optimizers capable of handling noisy, black-box, cost functions and stress-test them using a quantum circuit simulation environment with noise injection capabilities on individual gates. Our results indicate that specifically tuned optimizers are crucial to obtaining valid science results on NISQ hardware, and will likely remain necessary even for future fault tolerant circuits

Another spin in the wall : domain wall dynamics in perpendicularly magnetized devices

The world as we know it today would be completely different without spintronics. It has revolutionized the way we carry, store and exchange information in our daily lives. What is it? It is a research realm that combines the fundamental property of the electron, spin, and the charge property driving conventional electronics, hence: spin-tronics. Spintronics has until recently concentrated mainly on the manipulation of chargecurrent through the control of the magnetic state. Currently, a new paradigm has emerged that reverses this idea, basically by applying Newton’s law of action implies reaction. Instead of manipulating the charge-current by the magnetic state, it manipulates the magnetic state by a spin-polarized current, and it is gradually gaining interest. Spin-polarized current induced motion of a magnetic domain wall is the subject of this thesis.We try to use a spin polarized current to push a magnetic domain wall. The interaction between spin-current and the magnetic domain wall is still an open area for exploration; there are still many unanswered questions on the fundamental physics that brings it about. The prospect of new data storage, memory and even bio-related devices makes it a very lively and competitive research topic possibly relevant in shaping our future world. We chose perpendicularly magnetized devices as our material, and for a reason. In this class of materials the magnetic domain walls are very narrow; and this, was our assumption, should increase the interaction between the spin polarized current and the magnetization. Our research has made use of a great variety of experimental and nano-fabrication techniques. Since the nano-fabrication techniques were particularly new to our research group, they have been given ample attention in chapter 2. The material used in our research are perpendicularly magnetized ultrathin Co(FeB) layers

Transcending the Scottish Postmodern City: Ken MacLeod''s Future Urban Geographies

A place cannot exist if it has not been imagined, if it has not been perceived, as Alasdair Gray famously stated. Scottish science fiction (SF) goes a step further by emphasising the need not only to recognise and represent Scottish places, but also to recreate and to (re)imagine them in their possible futures. To (re)imagine Scotland and its places means to envision its potential spaces. Ken MacLeod is one of the figures who has successfully managed to set Scotland on the SF map. His novels Intrusion (2012) and Descent (2014) are remarkable examples of what some critics have called Transmodern fiction. Both are set in urban Scotland in the near-future and they portray new configurations of place. My analysis focuses on the interconnectedness of place as presented in the two novels, creating a new territory that transcends Scottish Postmodern urban geographies. In MacLeod''s fiction, a Transmodern urban place is conceived, where the glocal and the virtual meet in a new multifold reality without ever losing their local specificity

Pregnancy, childbirth and nursing in feminist dystopia: Marianne de Pierres’s Transformation space (2010)

Marianne de Pierres’s Transformation Space (2010) is a rare example of an Australian novel set in an apocalyptic and dystopic interstellar future where pregnancy, childbearing and nursing have a presence that is quite uncommon in Science Fiction (SF). Despite the fact that the genre of SF and that of space opera in particular have been traditionally quite male-oriented, in the last years feminist theories of several kinds have been an undeniable transformative influence. This article intends to analyse not only how these specifically female issues related to motherhood/mothering are presented in the novel, but also to explore their function and role. A close reading of these topics will show whether they endorse a solid feminist stance or are just colourful feminist details in a male-dominated space opera and, in turn, if they have a specifically narrative purpose in the context of the dystopic subgenre

Ectogenesis and representations of future motherings in Helen Sedgwick’s The Growing Season

After the boom of feminist science fiction in the 1970s, many such novels have tackled the different sociocultural understandings of gender and sexual reproduction. Conventionally, patriarchal thinking tends to posit a biological explanation for gender inequality: women are supposed to be child bearers and the primary caregivers, whereas men should provide for the family through their work. However, if men could share procreation, would these views change? A recent work of fiction exploring this question from multiple perspectives is Helen Sedgwick’s The Growing Season (2017), a novel that presents a near future in which babies can be grown in artificial wombs that can be carried around. As an analysis of the novel will show, The Growing Season creatively explores the existing tensions among contemporary understandings of motherhood and feminism(s), as well as developments in reproductive biotechnology, through the different perspectives offered by the heterodiegetic third-person narration and multiple focalisation. Ultimately, the voices of the different characters in the novel convey a polyhedral vision of possible future feminist motherhood(s) where ideas of personal freedom and codependency are radically reconceptualised—a rethinking that becomes especially important nowadays, for the biotechnological elements of this fictional dystopia are already a reality

Identity(ies) in Brian McCabe’s The Other McCoy

[Abstract] The Scottish writer Brian McCabe investigates the notion of identity through the topos of the Double in his novel The Other McCoy (1990). This interest in the Self/Other is closely related to the questions of language(s), the search for, and the making of the Self. McCoy, the novel’s protagonist, an unemployed comedian, is a multi-facetted character who often speaks with different voices taken from other people. McCabe uses the motif of the Double, or, rather, its Scottish version the “Dr Jekyll and Mr Hyde” topos, as a starting point for the exploration of identity construction, combining it with the idea of performance and the compulsion to role playing. In this sense it could be stated that The Other McCoy follows the haunting Scottish tradition of the literature of the double, which presents a culture engaged in the dialogue with the other, a conversation in different dialects