scholarly journals Revealing topology with transformation optics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lizhen Lu ◽  
Kun Ding ◽  
Emanuele Galiffi ◽  
Xikui Ma ◽  
Tianyu Dong ◽  
...  
Keyword(s):  
Physical Space ◽  
Real Space ◽  
Virtual Space ◽  
Transformation Optics ◽  
Coordinate Space ◽  
Dimensional System ◽  
Edge States ◽  
And Topology ◽  
Higher Dimensional ◽  
Insight Into

AbstractSymmetry deepens our insight into a physical system and its interplay with topology enables the discovery of topological phases. Symmetry analysis is conventionally performed either in the physical space of interest, or in the corresponding reciprocal space. Here we borrow the concept of virtual space from transformation optics to demonstrate how a certain class of symmetries can be visualised in a transformed, spectrally related coordinate space, illuminating the underlying topological transitions. By projecting a plasmonic system in a higher-dimensional virtual space onto a lower-dimensional system in real space, we show how transformation optics allows us to construct a topologically non-trivial system by inspecting its modes in the virtual space. Interestingly, we find that the topological invariant can be controlled via the singularities in the conformal mapping, enabling the intuitive engineering of edge states. The confluence of transformation optics and topology here can be generalized to other wave realms beyond photonics.

scholarly journals Virtuality in architecture: From perspective representation to augmented reality

2008 ◽  
Vol 6 (2) ◽  
pp. 235-241
Author(s):  
Rada Cahtarevic
Keyword(s):  
Complex Network ◽  
Physical Space ◽  
Spatial Location ◽  
Real Space ◽  
Virtual Space ◽  
History Of ◽  
Virtual Presence ◽  
Multidimensional Complex ◽  
The Spectator ◽  
Third Dimension

Notion of virtuality correlates mainly to visual aspects of space, presuming that basic qualities of physical space can be simulated by graphics, providing not just visual illusion of the third dimension of real space, but psychological involvement and transfer of the spectator into the space of the picture, giving him the sense of the spatial location and presence. Creation of virtual space that could be perceptually sensed and by virtual presence modified and shaped, explored and experienced, is not just result of advanced computer technology, but could be traced through history of spatial representations, that was based mainly in artistic and architectural practice. Architecture, being leading field that synthesize representation, construction and sense of spatial creation, had to be involved in explorations of multidimensional complex network of dynamic informational space, that is revealed in its real and virtual dimension as unique universe. Real-time experience in virtual space allow access in the alternative dimension to every open mind, giving him possibilities to play and work, to construct and represent, search, explore and express, augmenting reality into the complex network of information flow between visible and invisible space.

scholarly journals Topological phase transition between a normal insulator and a topological metal state in a quasi-one-dimensional system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Milad Jangjan ◽  
Mir Vahid Hosseini
Keyword(s):  
Phase Transition ◽  
Dimensional System ◽  
Inversion Symmetry ◽  
Topological Phase ◽  
Edge States ◽  
Zero Energy ◽  
One Dimensional ◽  
Topological Phase Transition ◽  
Metal State ◽  
Topological Metal

AbstractWe theoretically report the finding of a new kind of topological phase transition between a normal insulator and a topological metal state where the closing-reopening of bandgap is accompanied by passing the Fermi level through an additional band. The resulting nontrivial topological metal phase is characterized by stable zero-energy localized edge states that exist within the full gapless bulk states. Such states living on a quasi-one-dimensional system with three sublattices per unit cell are protected by hidden inversion symmetry. While other required symmetries such as chiral, particle-hole, or full inversion symmetry are absent in the system.

scholarly journals Topological gaps by twisting

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Matheus I. N. Rosa ◽  
Massimo Ruzzene ◽  
Emil Prodan
Keyword(s):  
Magnetic Field ◽  
Quantum Hall Effect ◽  
Twist Angle ◽  
Quantum Hall ◽  
Topological Phases ◽  
Edge States ◽  
Layered Systems ◽  
Virtual Laboratories ◽  
Higher Dimensional ◽  
Chern Numbers

AbstractTwisted bilayered systems such as bilayered graphene exhibit remarkable properties such as superconductivity at magic angles and topological insulating phases. For generic twist angles, the bilayers are truly quasiperiodic, a fact that is often overlooked and that has consequences which are largely unexplored. Herein, we uncover that twisted n-layers host intrinsic higher dimensional topological phases, and that those characterized by second Chern numbers can be found in twisted bi-layers. We employ phononic lattices with interactions modulated by a second twisted lattice and reveal Hofstadter-like spectral butterflies in terms of the twist angle, which acts as a pseudo magnetic field. The phason provided by the sliding of the layers lives on 2n-tori and can be used to access and manipulate the edge states. Our work demonstrates how multi-layered systems are virtual laboratories for studying the physics of higher dimensional quantum Hall effect, and can be employed to engineer topological pumps via simple twisting and sliding.

scholarly journals Rear-Seat Productivity in Virtual Reality: Investigating VR Interaction in the Confined Space of a Car

2021 ◽  
Vol 5 (4) ◽  
pp. 15
Author(s):  
Jingyi Li ◽  
Ceenu George ◽  
Andrea Ngao ◽  
Kai Holländer ◽  
Stefan Mayer ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Virtual Environment ◽  
Physical Space ◽  
Rear Seat ◽  
Virtual Space ◽  
Future Research ◽  
Confined Space ◽  
Physical Restraints ◽  
Working Environments ◽  
Research And Design

Ubiquitous technology lets us work in flexible and decentralised ways. Passengers can already use travel time to be productive, and we envision even better performance and experience in vehicles with emerging technologies, such as virtual reality (VR) headsets. However, the confined physical space constrains interactions while the virtual space may be conceptually borderless. We therefore conducted a VR study (N = 33) to examine the influence of physical restraints and virtual working environments on performance, presence, and the feeling of safety. Our findings show that virtual borders make passengers touch the car interior less, while performance and presence are comparable across conditions. Although passengers prefer a secluded and unlimited virtual environment (nature), they are more productive in a shared and limited one (office). We further discuss choices for virtual borders and environments, social experience, and safety responsiveness. Our work highlights opportunities and challenges for future research and design of rear-seat VR interaction.

scholarly journals H-plane horn antenna with enhanced directivity using conformal transformation optics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hossein Eskandari ◽  
Juan Luis Albadalejo-Lijarcio ◽  
Oskar Zetterstrom ◽  
Tomáš Tyc ◽  
Oscar Quevedo-Teruel
Keyword(s):  
Conformal Transformation ◽  
Phase Error ◽  
Three Dimensional ◽  
Physical Space ◽  
Horn Antenna ◽  
High Gain ◽  
Transformation Optics ◽  
Graded Index ◽  
Low Profile ◽  
Dielectric Lens

AbstractConformal transformation optics is employed to enhance an H-plane horn’s directivity by designing a graded-index all-dielectric lens. The transformation is applied so that the phase error at the aperture is gradually eliminated inside the lens, leading to a low-profile high-gain lens antenna. The physical space shape is modified such that singular index values are avoided, and the optical path inside the lens is rescaled to eliminate superluminal regions. A prototype of the lens is fabricated using three-dimensional printing. The measurement results show that the realized gain of an H-plane horn antenna can be improved by 1.5–2.4 dB compared to a reference H-plane horn.

scholarly journals Inverse-square law between time and amplitude for crossing tipping thresholds

2019 ◽  
Vol 475 (2222) ◽  
pp. 20180504 ◽  
Author(s):  
Paul Ritchie ◽  
Özkan Karabacak ◽  
Jan Sieber
Keyword(s):  
Dynamical System ◽  
Feedback Loop ◽  
Tipping Point ◽  
Dimensional System ◽  
Stochastic Forcing ◽  
Inverse Square Law ◽  
System A ◽  
Asymptotic Expressions ◽  
Higher Dimensional ◽  
Random Disturbances

A classical scenario for tipping is that a dynamical system experiences a slow parameter drift across a fold tipping point, caused by a run-away positive feedback loop. We study what happens if one turns around after one has crossed the threshold. We derive a simple criterion that relates how far the parameter exceeds the tipping threshold maximally and how long the parameter stays above the threshold to avoid tipping in an inverse-square law to observable properties of the dynamical system near the fold. For the case when the dynamical system is subject to stochastic forcing we give an approximation to the probability of tipping if a parameter changing in time reverses near the tipping point. The derived approximations are valid if the parameter change in time is sufficiently slow. We demonstrate for a higher-dimensional system, a model for the Indian summer monsoon, how numerically observed escape from the equilibrium converge to our asymptotic expressions. The inverse-square law between peak of the parameter forcing and the time the parameter spends above a given threshold is also visible in the level curves of equal probability when the system is subject to random disturbances.

Desiccation and low temperature attenuate the effect of UVC254 nm in the photobiont of the astrobiologically relevant lichens Circinaria gyrosa and Buellia frigida

2014 ◽  
Vol 14 (3) ◽  
pp. 479-488 ◽  
Author(s):  
T. Backhaus ◽  
R. de la Torre ◽  
K. Lyhme ◽  
J.-P. de Vera ◽  
J. Meeßen
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Photosynthetic Activity ◽  
Real Space ◽  
Fast Recovery ◽  
Protective Mechanisms ◽  
Subzero Temperatures ◽  
High Viability ◽  
Buellia Frigida ◽  
Insight Into

AbstractSeveral investigations on lichen photobionts (PBs) after exposure to simulated or real-space parameters consistently reported high viability and recovery of photosynthetic activity. These studies focused on PBs within lichen thalli, mostly exposed in a metabolically inactive state. In contrast, a recent study exposed isolated and metabolically active PBs to the non-terrestrial stressor UVC254 nm and found strong impairment of photosynthetic activity and photo-protective mechanisms (Meeßen et al. in 2014b). Under space and Mars conditions, UVC is accompanied by other stressors as extreme desiccation and low temperatures. The present study exposed the PBs of Buellia frigida and Circinaria gyrosa, to UVC in combination with desiccation and subzero temperatures to gain better insight into the combined stressors' effect and the PBs' inherent potential of resistance. These effects were examined by chlorophyll a fluorescence which is a good indicator of photosynthetic activity (Lüttge & Büdel in 2010) and widely used to test the viability of PBs after (simulated) space exposure. The present results reveal fast recovery of photosynthetic activity after desiccation and subzero temperatures. Moreover, they demonstrate that desiccation and cold confer an additional protective effect on the investigated PBs and attenuate the PBs' reaction to another stressor – even if it is a non-terrestrial one such as UVC. Besides other protective mechanisms (anhydrobiosis, morphological–anatomical traits and secondary lichen compounds), these findings may help to explain the high resistance of lichens observed in astrobiological studies.

scholarly journals NIMG-39. THE EVALUATION OF DIFFUSION TENSOR TRACTOGRAPHY USING MIXED REALITY INTEGRATED VIRTUAL SPACE AND REAL SPACE

2018 ◽  
Vol 20 (suppl_6) ◽  
pp. vi184-vi184
Author(s):  
Tsukasa Koike ◽  
Taichi Kin ◽  
Taketo Shiode ◽  
Shunsaku Takayanagi ◽  
Shota Tanaka ◽  
...  
Keyword(s):  
Mixed Reality ◽  
Diffusion Tensor ◽  
Real Space ◽  
Virtual Space ◽  
Diffusion Tensor Tractography

scholarly journals Technological displacement: The Coat Check interactive augmented reality installation in perspective

2021 ◽  
Author(s):  
Aysegul Koc
Keyword(s):  
Augmented Reality ◽  
Data Storage ◽  
Motion Tracking ◽  
Physical Space ◽  
Digital Technologies ◽  
Real Space ◽  
Embodied Experience ◽  
Global Networks ◽  
The Real ◽  
Technological Displacement

Technological Displacement: The Coat Check Interactive AR Installation in Perspective is a two-part dissertation that involves the research/creation of an augmented reality installation and a textual critique of displacement both as a socio-cultural phenomenon and a technology-driven status quo. Digital technologies involve a series of displacements from data storage and transfer to creating global networks. Going hand in hand with human mobilities technological displacement affects our lives and interactions deeply. Multimedia and digital overlaying of information and interconnectedness (mobile devices, tracking technologies, the internet...) make up our quotidian in various degrees, impelling us to be 'present' in time and places we actually are not. Technological displacement may be viewed as an extension of physical displacement of individuals and communities in that the need to reconcile, re-invent and innovatively market proximity becomes more and more an underlying theme of contemporary lives. Nowhere the reorientations of presence is more accentuated than 'augmented space', as described by Lev Manovich, "a physical space overlaid with dynamically changing information, multimedia in form and localized for each user." (219) It may be argued that our sense of reality is already 'augmented' by digital stimuli in many ways. Here I make the case that in an augmented or digitally enhanced environment we are displaced multiple times, or "multiplaced". Augmentation is superimposing multimedia to real space, blurring the boundary between the real and the virtual, creating a heterogeneous space defined neither by the standards of the virtual nor the real but the coexistence and cooperation of both. Augmented reality functions on the principle of multiple displacements in that real space is not a backdrop to multimedia: it is indispensable to the overall embodied experience. I created the Coat Check in 2011 using motion tracking technologies (Intersense IS900), specialized cameras (Point Grey 360 degree Spherical Vision Camera), screens (Fog Screen), software (Max/MSP), tools and applications (Snapdragon AR). The conceptualization of The Coat Check is based on an analogy between digital technologies and coat checks that are both storage, retrieval and displacement systems. The Coat Check also raises questions on identity and history as it refers to belonging, temporality, and mobility.

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