Classical World Research Articles

Modern Application of Bai` al-Sarf (Currency Exchange) From Maqasid Al-Shari’ah Perspective: A Scoping Review

Bai’ al-sarf widely known as currency exchange is an important sale contract both in classical and contemporary world. This scoping review looks into the objectives behind the rulings set by the Shari’ah for this sale contract. These objectives are sorted out from the commentaries of the hadith and the deliberations of the jurists through textual analysis method. Some of the modern applications such as T+2 and Islamic Foreign Currency Exchange (FX) Swap structures are briefly juxtaposed against the objectives of bai’ al-sarf we discovered. Objectives of Shari’ah rulings in spot exchange is to avoid falling into the sale of debt against debt (al-kali bi al-kali), prevention of payment delay by one of the counter parties, prevention of conflict between the counter parties, and last not least to avoid falling into exchange contracts that will induce riba. Keywords: Bai’ al-sarf, currency exchange, spot seizing (al-taqabud fi al-majlis), equal counter-values (al-tamathul), sad bab al-niza’ (closing the door of conflict), riba.

Advancing Quantum Technologies – Chances and Challenges

The development of quantum mechanics and quantum physics in general is one of the greatest intellectual achievements of the 20th century. Initially, quantum physicists focused on mathematically describing and understanding the laws of a micro-world, comprised of atoms, molecules and photons. Nuclei and sub-atomic particles were discovered, particle physics evolved, and complex quantum systems in chemistry and solid-state physics are now described in terms of quantum physics. Within a century, quantum physics became the framework, which allows us to describe and predict, albeit with probabilities, the behavior of the microscopic world as we know it. The powerful quantum framework led to revolutionary technical advances for a century, such as semiconductor technology and the entire electronics industry based on it, enabling computers and the information age. The development of lasers found applications in many areas of our current technologies; we use them for printers, storing and retrieving information using CDs, industrial welding, medical surgery, and for range finding and communication purposes. Medical imaging using MRI is now a routine instrument, as are precision measurements using tunneling and atomic force microscopes. Superconducting technologies are used for high magnetic fields and many more current technologies are based on and enabled by the laws of quantum physics. While the framework of quantum physics has thus proven to be extremely successful and powerful, throughout the last century there were many conceptual, and to some extent philosophical, discussions on our understanding of quantum physics. As early as the 1930s, Einstein and Schrödinger realized that quantum physics allows for some peculiar states, which Schrödinger called “entangled”, which have a non-local character and thus do find an easy interpretation in our classical world. It took a few more decades until John Bell conceived a way to quantify such states, which thus became amenable to measurements. Only in the eighties and nineties of the last century did the generation of entangled states, their characterization and their subsequent application become feasible and accessible in laboratories. Early on, Bell states were proposed for applications in quantum communication, employing protocols based on teleportation. Soon, entanglement was recognized to be useful also for sensing, for precision measurements and eventually for quantum information processing. Starting with the early concept of a trapped-ion quantum computer introduced by Ignacio Cirac and Peter Zoller in 1995, many other platforms were proposed for quantum information processing, based on superconducting quantum bits, photonic processes, engineered quantum dots and many more. The first decade of the 21st century saw an explosive development of quantum information physics, which is by now a mature field and increasingly focuses on applications. Worldwide efforts are ongoing to realize quantum networks for secure communication and to implement quantum computers. Enhanced sensing has been demonstrated using advanced quantum states, and quantum simulators have been developed, already tackling problems that are hard to compute with classical computers. While architectures for full-fledged quantum computers are already available, the realization of such computers still requires the routine implementation of error correction, which is not yet available, for full scalability. Currently, noisy intermediate-scale quantum (NISQ) processors are already used for computations and are even accessible via cloud services. Since about 2000, quantum technologies have been developed for many platforms with the aim to surpass the capablities of their classical counterparts. Many such devices now make use of entangled states, which are seen as the new resource for advanced quantum technologies. For this, describing, understanding and generally mastering the generation and manipulation of entanglement is a key element. Moreover, both hardware and software technologies have to be improved in order to better control quantum devices. Mastering quantum phenomena for communication, metrology, simulation and computation purposes is currently one of the hottest topics in science since the wide applicability of quantum technologies will revolutionize these fields. The development of advanced quantum technologies is thus seen worldwide as a strategic area for generating technical knowledge and industrial evolution. This special issue intends to showcase the breadth and impact of the ongoing research in advancing quantum technologies. We have invited a selection of renowned scientists to present their work, and we are confident that this issue will find a broad readership and attract much interest within the scientific community.

Interference experiment, anomalous weak value, and Leggett-Garg test of macrorealism

Macrorealism is a classical world view asserting that the properties of macro-objects exist independently and irrespective of observation. One practical approach to test this view in quantum theory is to observe the quantum coherence for a macro-object in an interference experiment. An elegant and conceptually appealing approach for testing the notion of macrorealism in quantum theory is through the violation of Leggett-Garg inequality. However, a conclusive Leggett-Garg test hinges on how the noninvasive measurability criteria are guaranteed in an experiment and remains a debated issue to date. In this work, we connect the practical and the conceptual approaches for testing the macrorealism through the weak value. We argue that whenever a quantum effect is observed in an interference experiment there is an existence of anomalous weak value. Further, we demonstrate that whenever such weak value exists, one obtains the violation of a Leggett-Garg inequality in any interference experiment. Since in a path-only interference experiment effectively no prior measurement is performed, the Leggett-Garg test of macrorealism presented here is without assuming the noninvasive measurability. We provide a rigorous discussion about the assumptions involved in the Leggett-Garg scenario and how our scheme fits into it. Further, we provide a simple argument about the macrorealistic understanding of our results by using the recently developed approach involving quasiprobability.

Narrowing the Parameter Space of Collapse Models with Ultracold Layered Force Sensors.

Despite the unquestionable empirical success of quantum theory, witnessed by the recent uprising of quantum technologies, the debate on how to reconcile the theory with the macroscopic classical world is still open. Spontaneous collapse models are one of the few testable solutions so far proposed. In particular, the continuous spontaneous localization (CSL) model has become subject of intense experimental research. Experiments looking for the universal force noise predicted by CSL in ultrasensitive mechanical resonators have recently set the strongest unambiguous bounds on CSL. Further improving these experiments by direct reduction of mechanical noise is technically challenging. Here, we implement a recently proposed alternative strategy that aims at enhancing the CSL noise by exploiting a multilayer test mass attached on a high quality factor microcantilever. The test mass is specifically designed to enhance the effect of CSL noise at the characteristic length r_{c}=10^{-7} m. The measurements are in good agreement with pure thermal motion for temperatures down to 100mK. From the absence of excess noise, we infer a new bound on the collapse rate at the characteristic length r_{c}=10^{-7} m, which improves over previous mechanical experiments by more than 1 order of magnitude. Our results explicitly challenge a well-motivated region of the CSL parameter space proposed by Adler.

Quantum uncertainty relations of two quantum relative entropies of coherence

The uncertainty relation reveals the intrinsic difference that distinguishes the quantum world from the classical world. In this paper, the quantum uncertainty relations of the sandwiched R\'enyi relative entropy of coherence (SRREOC) and unified $(\ensuremath{\alpha},\ensuremath{\beta})$-relative entropy of coherence (UREOC) are studied. First, the uncertainty relation of the SRREOC for pure states, with extension to mixed states by convex-roof construction, is given in a $d$-dimensional quantum system. Second, the analytical formula of the UREOC is presented; it is shown that the UREOC is a good candidate for a quantum coherence measure. Furthermore, the quantum uncertainty relation of the UREOC for pure states is obtained in a $d$-dimensional quantum system, then it is generalized to mixed states. In addition, our results cover the quantum uncertainty relations of the other three coherence measures. Third, two methods are given to compare the lower bounds of the SRREOC and UREOC for single-qubit pure states. By comparison, we find that the results in this paper not only can be applied to single-qubit states but also can be extended to a $d$-dimensional quantum system.

Cost of Quantum Entanglement Simplified.

Quantum entanglement is a key physical resource in quantum information processing that allows for performing basic quantum tasks such as teleportation and quantum key distribution, which are impossible in the classical world. Ever since the rise of quantum information theory, it has been an open problem to quantify entanglement in an information-theoretically meaningful way. In particular, every previously defined entanglement measure bearing a precise information-theoretic meaning is not known to be efficiently computable, or if it is efficiently computable, then it is not known to have a precise information-theoretic meaning. In this Letter, we meet this challenge by introducing an entanglement measure that has a precise information-theoretic meaning as the exact cost required to prepare an entangled state when two distant parties are allowed to perform quantum operations that completely preserve the positivity of the partial transpose. Additionally, this entanglement measure is efficiently computable by means of a semidefinite program, and it bears a number of useful properties such as additivity and faithfulness. Our results bring key insights into the fundamental entanglement structure of arbitrary quantum states, and they can be used directly to assess and quantify the entanglement produced in quantum-physical experiments.

The architecture of access: ramps at ancient Greek healing sanctuaries

Ancient Greece is well known for its many temples and sanctuaries, including several dedicated to healing and associated cults. Informed by disability studies, this article analyses the architecture of public spaces and facilities, alongside epigraphic, iconographic and literary evidence, to argue that the ancient Greeks sought to ensure the accessibility of healing sanctuaries. Even without a framework of civil rights as we understand them today, the builders of these sites made architectural choices that enabled individuals with impaired mobility to access these spaces. It is hoped that this research may stimulate further investigations into accessibility at other sites in the Classical world and beyond.

Measurement of Backaction from Electron Spins in a Gate-Defined GaAs Double Quantum dot Coupled to a Mesoscopic Nuclear Spin Bath.

Decoherence of a quantum system arising from its interaction with an environment is a key concept for understanding the transition between the quantum and classical world as well as performance limitations in quantum technology applications. The effects of large, weakly coupled environments are often described as a classical, fluctuating field whose dynamics is unaffected by the qubit, whereas a fully quantum description still implies some backaction from the qubit on the environment. Here we show direct experimental evidence for such a backaction for an electron-spin qubit in a GaAs quantum dot coupled to a mesoscopic environment of order 10^{6} nuclear spins. By means of a correlation measurement technique, we detect the backaction of a single qubit-environment interaction whose duration is comparable to the qubit's coherence time, even in such a large system. We repeatedly let the qubit interact with the spin bath and measure its state. Between such cycles, the qubit is reinitialized to different states. The correlations of the measurement outcomes are strongly affected by the intermediate qubit state, which reveals the action of a single electron spin on the nuclear spins.

Towards a distributed quantum computing ecosystem

The Quantum Internet, by enabling quantum communications among remote quantum nodes, is a network capable of supporting functionalities with no direct counterpart in the classical world. Indeed, with the network and communications functionalities provided by the Quantum Internet, remote quantum devices can communicate and cooperate for solving challenging computational tasks by adopting a distributed computing approach. The aim of this paper is to provide the reader with an overview about the main challenges and open problems arising with the design of a Distributed Quantum Computing ecosystem. For this, we provide a survey, following a bottom-up approach, from a communications engineering perspective. We start by introducing the Quantum Internet as the fundamental underlying infrastructure of the Distributed Quantum Computing ecosystem. Then we go further, by elaborating on a high-level system abstraction of the Distributed Quantum Computing ecosystem. Such an abstraction is described through a set of logical layers. Thereby, we clarify dependencies among the aforementioned layers and, at the same time, a road-map emerges.

Claudia Nelson and Anne Morey, Topologies of the Classical World in Children's Fiction: Palimpsests, Maps, and Fractals

Review/Recension

El proceso para realizar una inscripción en la Edad Media y sus evidencias hoy: los talleres epigráficos medievales

El modo de producción epigráfico en el mundo clásico está bien documentado, no así en el mundo medieval. En esta etapa algunas de las fases de realización de los epígrafes resultan difusas por la escasa información que de ellas se conserva. El presente artículo permite comprender el proceso de producción epigráfica durante la Edad Media, a través de la compilación de la escasa y dispersa información que sobre las distintas fases de la realización de la inscripción medieval se conservan.

If the propagator of QED were reversed, the mathematics of Nature would be much simpler


 
 
 In Quantum ElectroDynamics (QED) the propagator is a function that describes the probability amplitude of a particle going from point A to B. It summarizes the many paths of Feynman’s path integral approach. We propose a reverse propagator (R-propagator) that, prior to the particle’s emission, summarizes every possible path from B to A. Wave function collapse occurs at point A when the particle randomly chooses one and only one of many incident paths to follow backwards with a probability of one, so it inevitably strikes detector B. The propagator and R-propagator both calculate the same probability amplitude. The R-propagator has an advantage over the propagator because it solves a contradiction inside QED, namely QED says a particle must take EVERY path from A to B. With our model the particle only takes one path. The R-propagator had already taken every path into account. We propose that this tiny, infinitesimal change from propagator to R-propagator would vastly simplify the mathematics of Nature. Many experiments that currently describe the quantum world as weird, change their meaning and no longer say that. The quantum world looks and acts like the classical world of everyday experience.
 
 

Identification of Selective Sweeps in the Domesticated Table and Wine Grape (Vitis vinifera L.).

Grapevine (Vitis vinifera) is one of the most important fruit species in the Classical Mediterranean world. It is thought to have been domesticated 6,000–8,000 years ago in the Near East. However, the domestication of its wild relative into wine grapes or table grapes remains largely unknown. In this study, we analyzed 30 table grapes, 30 wine grapes, 30 dual-purpose grape accessions, as well as 30 wild relatives (Vitis vinifera ssp. sylvestris). The phenotypic comparison showed striking differences in berry weight, acidity and the content of aroma. Based on a total of 7,522,958 single-nucleotide polymorphisms, we identified several significant selective sweep regions for table and wine grapes. Besides the well-known sex-determination locus on chromosome 2, the other four highest signals shared by table and wine grapes could not be linked to the known QTLs. The identification of these genomic regions under selection sweep may reveal agronomically important traits that have been selected during grape domestication. This information not only sheds light on the mechanisms of adaptions and diversification, but also guide the genetic improvement in breeding programs.

Minimum measurement time: lower bound on the frequency cutoff for collapse models

The CSL model predicts a progressive breakdown of the quantum superposition principle, with a noise randomly driving the state of the system towards a localized one, thus accounting for the emergence of a classical world within a quantum framework. In the original model the noise is supposed to be white, but since white noises do not exist in nature, it becomes relevant to identify some of its spectral properties. Experimental data set an upper bound on its frequencies, while in this paper we bound it from below. We do so in two ways: by considering a ‘minimal’ measurement setup, requiring that the collapse is completed within the measurement time; and in a measurement modeling-independent way, by requiring that the fluctuations average to zero before the measurement time.

BİLGELİĞİN PORTRELERİ: AVRUPA RESMİNDE ANTİK YUNAN FİLOZOFLARI

The cultural heritage of Ancient Greece had left significant marks on the art of European painting. This admiration for the ancient culture can be seen starting from the Renaissance era which was inspired by the classical world and humanism. Baroque art in the 17th century and Neoclassical style of the 18th century also presented the traces of the ancient Greek civilization. Greek mythological figures and prominent people from the cultural life had been the subject of pictures. The focus of this study will be the portraits of the thinkers. The pictorial presentations of the life stories and anectodes of Ancient Greek philosophers such as Pythagoras, Heraclitus, Democritus, Socrates, Plato, Aristotle and Diogenes will be explored.

Can a contractarian be a paternalist? The logic of James M. Buchanan’s system

Abstract At various points in his work, James Buchanan mentions favorably the idea of private constitutional choice, that is, it can be rational for a present-biased individual to constrain her future behavior by self-imposed rules of personal conduct. Given that in a classical liberal world such self-constitutions would face no political or legal obstacle, we ask whether reasonable people would call on the state to assist them in the enforcement of their personal constitutions. In this paper, we provide several arguments for the incompatibility of Buchanan’s contractarianism with various forms of state paternalism.

The Techne of Nutrition in Ancient Greek Philosophy

The preparation of food and nutrition is a pervasive techne in the classical Greek world. Indeed, food technology may be a defining characteristic of humanity (Levi-Strauss, 1964). We begin with a glimpse of a tension in the use of the word techne in relation to the preparation of food in Plato’s Gorgias 462d-e. Turning to the Presocratics, we discern three distinct perspectives on food, those of Empedocles, Anaxagoras, and the treatise Regimen (Περὶ Διαίτης). In Regimen, we find an anticipation of the distinctions made by Plato in the Gorgias passage, and trace some of the implications in what we may call the “food technology” of this treatise that manages to be both philosophical and technically informative.

Pure States of Maximum Uncertainty with Respect to a Given POVM

One of the differences between classical and quantum world is that in the former we can always perform a measurement that gives certain outcomes for all pure states, while such a situation is not possible in the latter one. The degree of randomness of the distribution of the measurement outcomes can be quantified by the Shannon entropy. While it is well known that this entropy, as a function of quantum states, needs to be minimized by some pure states, we would like to address the question how ‘badly’ can we end by choosing initially any pure state, i.e., which pure states produce the maximal amount of uncertainty under given measurement. We find these maximizers for all highly symmetric POVMs in dimension 2, and for all SIC-POVMs in any dimension.

Quantum synchronization in nanoscale heat engines.

Owing to the ubiquity of synchronization in the classical world, it is interesting to study its behavior in quantum systems. Though quantum synchronization has been investigated in many systems, a clear connection to quantum technology applications is lacking. We bridge this gap and show that nanoscale heat engines are a natural platform to study quantum synchronization and always possess a stable limit cycle. Furthermore, we demonstrate an intimate relationship between the power of a coherently driven heat engine and its phase-locking properties by proving that synchronization places an upper bound on the achievable steady-state power of the engine. We also demonstrate that such an engine exhibits finite steady-state power if and only if its synchronization measure is nonzero. Finally, we show that the efficiency of the engine sets a point in terms of the bath temperatures where synchronization vanishes. We link the physical phenomenon of synchronization with the emerging field of quantum thermodynamics by establishing quantum synchronization as a mechanism of stable phase coherence.

When Wisdom Calls: Philosophical Protreptic in Antiquity ed. by O. Alieva, A. Kotzé, S. Van der Meeren

Reviewed by: When Wisdom Calls: Philosophical Protreptic in Antiquity ed. by O. Alieva, A. Kotzé, S. Van der Meeren Diego De Brasi Alieva, O., Kotzé, A., and Van der Meeren, S. (edd.) 2018. When Wisdom Calls: Philosophical Protreptic in Antiquity. Turnhout: Brepols. Pp. 517. ISBN 978-2-503-56855-6. €100.00. At least since Paul Hartlich's dissertation De exhortationum a Graecis Romanisque scriptarum historia et indole (Leipzig: Hirzel 1889) the study of protreptic has been a significant aspect of research on classics, especially ancient philosophy and early Christianity. However, while scholarly attention in the last 130 years focused more on canonical authors like Plato, Aristotle, Cicero, and Paul of Tarsus, authors from the imperial era and late antiquity have been slightly neglected and a comprehensive, up-to-date overview of ancient protreptic literature is still missing. The book under review represents, thus, an extremely welcome addition to the analysis of ancient protreptic as it tries to fill this gap. Indeed, the volume offers a very good outline of protreptic and its interaction with other literary genres from the 'beginning' up to the 'end' of Antiquity. Of course, one cannot and should not expect from a collective volume a systematic approach to the subject matter, but the absence of methodological unity is not problematic in this case. As Olga Alieva in her inspiring opening essay shows ('Protreptic: a protean genre', pp. 29–45), scholars are far from reaching consensus on the criteria which define protreptic. Only the quite general claim that protreptic, as its etymology suggests, aims at the 'conversion' of the addressed audience seems to be widely accepted. Further, as Alieva also shows, and many contributors to the volume claim, even ancient authors – or at least some of them – use the term προτρέπειν and its cognates vaguely and do not distinguish clearly, for instance, between protreptic and παραίνεσις. In this regard, Alieva seems to side with those scholars of early Christianity who argue for different functions of protreptic and παραίνεσις (cf. also the contribution by Annemaré Kotzé, esp. p. 368). Although she recognizes the importance of questioning this dichotomy, Alieva explicitly challenges the analysis of Diana Swancutt, who systematically disputed the traditional interpretation. Swancutt argues that the difference between protreptic and παραίνεσις is explicable in socio-cultural [End Page 255] terms and is not an expression of different functions.1 Alieva is right in pointing out that we cannot find explicit mentions of socio-cultural aspects in the texts examined by Swancutt. However, it is questionable whether the absence of evidence in ancient texts is evidence of absence. We should not forget, indeed, that ancient philosophical texts are usually the expression of a 'closed' socio-cultural community, and philosophical authors perhaps did not feel the need to put the spotlight on such aspects in their arguments. After Alieva's contribution, which in some way represent a second, methodological introduction to the whole collection (while the actual 'Introduction', pp. 19–27, mainly epitomizes all contributions), the volume offers sixteen 'case studies' ranging from Hesiod to Marinus of Neapolis and dealing with more (e.g. Plato, Aristotle, Cicero, Seneca, Galen, Augustine) and less (e.g. Philo of Alexandria, Lucian of Samosata, Marinus) 'canonical' authors. The last essay by Sophie van der Meeren ('Protreptique et isagogique: les vestibules de la philosophie', pp. 407–55) deals more generally with the protreptic implications of late antique isagogical literature. The essays are subdivided into two main sections ('Classical and Hellenistic World' pp. 47–227, 'Imperial Rome' pp. 229–455) and ordered mainly chronologically. There is only one easily explicable exception: Johan C. Thom's paper deals with Iamblichus' use of protreptic but is the second contribution in the section on 'Classical and Hellenistic World' since it also elaborates on Iamblichus' use of the so-called Pythagorean Sayings. A general bibliography and an index locorum complete the volume. All contributions are well written, of very high scientific standards and quite engaging, but since it would be impossible to assess every single one, I will focus on very few essays which I found particularly stimulating. Johan C. Thom's contribution focuses, as I mentioned above, on Iamblichus' Protrepticus and its use of Pythagorean Sayings ('Protreptic and Pythagorean sayings: Iamblichus' Protrepticus...