Using quantum theory to reduce the complexity of input-output processes

All natural things process and transform information. They receive environmental information as input, and transform it into appropriate output responses. Much of science is dedicated to building models of such systems -- algorithmic abstractions of their input-output behavior that allow us to simulate how such systems can behave in the future, conditioned on what has transpired in the past. Here, we show that classical models cannot avoid inefficiency -- storing past information that is unnecessary for correct future simulation. We construct quantum models that mitigate this waste, whenever it is physically possible to do so. This suggests that the complexity of general input-output processes depends fundamentally on what sort of information theory we use to describe them.Comment: 10 pages, 5 figure

Symbolic and cued immersion: paratextual framing strategies on the Doctor Who Experience Walking Tour

This article employs autoethnographic reflections to contribute towards debates concerning film-induced tourism by analysing the officially endorsed Doctor Who Experience Walking Tour around filming locations from the BBC series in Cardiff Bay, Wales. Approaching this tour as an example of paratextuality, the article pursues two arguments. First, it reflects upon the attempts used within the tour for encouraging connection between participants and the locations visited from the perspective of immersion. However, noting preceding positions, it is recognized that the tour constructs forms of imaginative immersion. The terms symbolic and cued immersion are subsequently introduced to consider the strategies that the tour employs to position fans and engage them with its frequently quotidian spaces. Second, the article explores the links between the tour’s immersive strategies and its institutional context, arguing that these assist in reinforcing core brand values regarding BBC Worldwide

SARS-CoV-2: Tale of a Microscopic Murderer

Independent Study Research in progress for BIOL1406: Biology for Science Majors I Faculty Mentor: Amina Tassa, Ph.D. I am delighted to introduce Josiah Garner’s “SARS-CoV-2: Tale of a Microscopic Murderer.” This independent study assignment explores the impact of a novel, deadly, and worldwide virus. The assignment also examines the fast development of vaccines to control the spread and reduce the symptoms of the virus. Josiah’s paper focuses on the early history of the emergence of COVID-19, the world response, and vaccine development. He demonstrates critical thinking skills and effectively utilizes various research methods to obtain and communicate his information. Josiah skillfully analyzed the information about the novel virus SARS-CoV-2 and current vaccines. After devoting substantial time to gathering scientific research about the virus, he shaped it into a story about the discovery of the virus, the spread of the pathogen, and the worldwide response to the emerging health crisis. Josiah worked diligently online, at the college’s library, and via Zoom meetings to perfect his research paper. He has taken a difficult but timely subject and summarized its complexity through his research story

Guaranteed energy-efficient bit reset in finite time

Landauer's principle states that it costs at least kTln2 of work to reset one bit in the presence of a heat bath at temperature T. The bound of kTln2 is achieved in the unphysical infinite-time limit. Here we ask what is possible if one is restricted to finite-time protocols. We prove analytically that it is possible to reset a bit with a work cost close to kTln2 in a finite time. We construct an explicit protocol that achieves this, which involves changing the system's Hamiltonian avoiding quantum coherences, and thermalising. Using concepts and techniques pertaining to single-shot statistical mechanics, we further develop the limit on the work cost, proving that the heat dissipated is close to the minimal possible not just on average, but guaranteed with high confidence in every run. Moreover we exploit the protocol to design a quantum heat engine that works near the Carnot efficiency in finite time.Comment: 5 pages + 5 page technical appendix. 5 figures. Author accepted versio

The microstructure and microtexture of zirconium oxide films studied by transmission electron backscatter diffraction and automated crystal orientation mapping with transmission electron microscopy

A detailed characterization of nanostructured thin zirconium oxide films formed during aqueous corrosion of a nuclear-grade zirconium alloy (Zircaloy-4) has been carried out by means of two novel, ultra-high-spatial-resolution grain mapping techniques, namely automated crystal orientation mapping in the transmission electron microscope (TEM) and transmission electron backscatter diffraction (t-EBSD). While the former provided excellent spatial resolution with the ability to identify tetragonal ZrO<sub>2</sub> grains as small as ∼5 nm, the superior angular resolution and unambiguous indexing with t-EBSD enabled verification of the TEM observations. Both techniques revealed that in a stress-free condition (TEM foil prepared by focused ion beam milling), the oxide consists mainly of well-oriented columnar monoclinic grains with a high fraction of transformation twin boundaries, which indicates that the transformation from tetragonal to monoclinic ZrO<sub>2</sub> is a continuous process, and that a significant fraction of the columnar grains transformed from stress-stabilized tetragonal grains with (0 0 1) planes parallel to the metal–oxide interface. The TEM analysis also revealed a small fraction of size-stabilized, equiaxed tetragonal grains throughout the oxide. Those grains were found to show significant misalignment from the expected (0 0 1) growth direction, which explains the limited growth of those grains. The observations are discussed in the context of providing new insights into corrosion mechanisms of zirconium alloys, which is of particular importance for improving service life of fuel assemblies used in water-cooled reactors

The classical-quantum divergence of complexity in modelling spin chains

The minimal memory required to model a given stochastic process - known as the statistical complexity - is a widely adopted quantifier of structure in complexity science. Here, we ask if quantum mechanics can fundamentally change the qualitative behaviour of this measure. We study this question in the context of the classical Ising spin chain. In this system, the statistical complexity is known to grow monotonically with temperature. We evaluate the spin chain's quantum mechanical statistical complexity by explicitly constructing its provably simplest quantum model, and demonstrate that this measure exhibits drastically different behaviour: it rises to a maximum at some finite temperature then tends back towards zero for higher temperatures. This demonstrates how complexity, as captured by the amount of memory required to model a process, can exhibit radically different behaviour when quantum processing is allowed.Comment: 9 pages, 3 figures, comments are welcom

Maximum one-shot dissipated work from Renyi divergences

Thermodynamics describes large-scale, slowly evolving systems. Two modern approaches generalize thermodynamics: fluctuation theorems, which concern finite-time nonequilibrium processes, and one-shot statistical mechanics, which concerns small scales and finite numbers of trials. Combining these approaches, we calculate a one-shot analog of the average dissipated work defined in fluctuation contexts: the cost of performing a protocol in finite time instead of quasistatically. The average dissipated work has been shown to be proportional to a relative entropy between phase-space densities, to a relative entropy between quantum states, and to a relative entropy between probability distributions over possible values of work. We derive one-shot analogs of all three equations, demonstrating that the order-infinity Renyi divergence is proportional to the maximum possible dissipated work in each case. These one-shot analogs of fluctuation-theorem results contribute to the unification of these two toolkits for small-scale, nonequilibrium statistical physics.Comment: 8 pages. Close to published versio