Exploring connections between open quantum systems, relativity and complex quantum networks

This thesis is a collection of works focusing on interrelations between the fields of special relativity, open quantum systems and complex networks. As each of the aforementioned fields encompasses a huge variety of topics, the thesis contains a selection of particular connections. The first half of the thesis considers an open quantum systems approach to the description of relativistic phenomena. As the aforementioned phenomena often involve dynamically evolving counterparts, some non-Markovian aspects of open quantum systems are initially explored. Conditions for complete positivity are derived for a type of phase-covariant time-local master equation and then applied to a non-Markovian master equation with heuristically-derived decay rates. This is relevant in cases when the physicality of the master equation cannot be postulated. The first relativistic system considered is a superposition of coherent states in a gravitational gradient. It is shown to exhibit decoherence induced by gravitational time dilation through interaction between inner degrees of freedom and the centre of mass of the superposition. The decoherence is quantified using various, widely-used non-classicality measures. The decoherence rates are then compared to decoherence induced by classical noise to roughly evaluate the experimental precision necessary to detect gravitationally induced decoherence. In the second relativistic system, the Unruh effect is modeled as an open system where an Unruh-deWitt detector is interacting with bosonic fields. A master equation with time-dependent decay rates for the open system is derived by assuming a non-conventional spacetime path profile for the detector. A particular parameter governing the physical evolution is identified. The system is shown to exhibit non-Markovianity within the completely positive domain of the master equation, the latter ensured by the conditions derived before. The second half of the thesis starts with a definition of complex networks, which are yet not a commonly used tool in quantum physics. The concept of pairwise tomography networks is then introduced as a way to represent many-body quantum states. As the number of pairwise connections grows quadratically with the number of nodes, an efficiently scaling measurement scheme to recover the pairwise tomography networks is presented. The scheme and the concept of pairwise tomography networks are demonstrated to be useful in various applications and the results of a proof-of-principle experiment are shown. One application explored is a paradigmatic spin chain model known as the XX model. A pairwise entanglement network representation of the XX model is shown to suggest new phenomena such as gradual establishment of quasi-long range order accompanied by a symmetry regarding single-spin concurrence distributions. The existence of structural classes and a cyclic self-similarity in the state are revealed.Tämä väitöskirja on erikoisen suhteellisuusteorian, avoimien kvanttisysteemien ja kompleksisten verkkojen alojen läpileikkauksiin keskittyvä kokoelma. Sillä jokainen edellämainituista aloista sisältää valtavan moninaisuuden erilaisia käsitteitä, väitöskirjaan sisältyy valikoima tietynlaisia yhteyksiä. Väitöskirjan ensimmäinen puolisko käsittelee avoimien kvanttisysteemien lähestymistapaa relativististen ilmiöiden kuvaamiseen. Edellä mainitut ilmiöt yleensä sisältävät dynaamisesti kehittyviä osia, joten tutkitaan avoimien kvanttisysteemien ei-markovisia näkökulmia. Täyspositiivisuuden ehdot johdetaan tietyntyyppiselle faasi-kovariantille ajassa lokaalille master-yhtälölle. Nämä ehdot sovitellaan ei-markoviselle master-yhtälölle jossa on heuristisesti johdetut hajoamisnopeudet. Tämä on merkityksellistä silloin kun master-yhtälön fysikaalisuus ei ole postuloitavissa. Ensimmäinen tarkasteltu relativistinen systeemi on koherenttien tilojen superpositio gravitationaalisessa gradientissa. Sen osoitetaan ilmentävän gravitaationaalisen aikadilataation aiheuttamaa dekoherenssiä sisäisten vapausasteiden ja massakeskipisteen välisten vuorovaikutusten kautta. Tämä dekoherenssi kvantifioidaan käyttämällä useilla laajassa käytössä olevilla ei-klassisuusmitoilla. Dekoherenssinopeuksia verrataan klassisen melun aiheuttamaan dekoherenssiin alustavan gravitaation indusoiman dekoherenssin kokeelliseen havaintoon tarvittavan mittaustarkkuusarvion tekemiseksi. Toisessa tarkasteltavassa relativistisessa systeemissä, Unruhin ilmiö mallinnetaan avoimena kvanttisysteeminä jossa Unruh-deWitt detektori vuorovaikuttaa bosonikenttien kanssa. Olettamalla detektorille epätavanomainen aika-avaruuspolkuprofiili johdetaan avoimelle kvanttisysteemille master-yhtälö ajasta riippuvin hajoamisnopeuksin. Tunnistetaan erityinen fyysista evoluutiota hallitseva parametri. Systeemin näytetään omaavan ei-markovisuutta master-yhtälön täyspositiivisilla alueilla, täyspositiivisuus taataan aiemmin johdetulla tavalla Väitöskirjan toisen puoliskon alussa määritellään kompleksiset kvantti-verkot, jotka eivät vielä ole laajasti käytettyjä työkaluja kvanttifysiikassa. Esitellään uusi tapa esittää monikappalekvanttitiloja parittaisina tomografiaverkkoina. Parittaisten yhteyksien lukumäärän ollessa neliöllisesti verrannollinen solmupisteiden lukumäärään, esitetään tehokkaasti skaalautuva parittaisia tomografiaverkkoja muodostava mittausskeema. Skeema ja parittaisten tomografiaverkkojen konsepti osoitetaan hyödyllisiksi erilaisissa sovelluksissa ja esitetään periaatetodistuskokeen tulokset. Eräänä sovelluksena esitetään XX mallina tunnettu paradigmaattinen spinketjumalli. XX mallin parittaisen kietoutumisen verkkoesityksen näytetään tuovan ilmi uusia ilmiöitä kuten vaiheittaisen kvasipitkän etäisyyden järjestyksen yksittäisten spinien konkurrenssidistribuutioiden symmetrialla. Paljastetaan tilan rakenteellisten luokkien ja syklisten itse-samankaltaisuuksien olemassaolo

Linkages between Experiencing COVID-19 and Levels of Political Support in Russia

The ongoing COVID-19 pandemic has left noticeable traces in everyday life of Russian society. Eighty percent of Russians had to alter their lifestyles due to the virus, with half reporting that their incomes shrank, and this share keeps growing. Has the pandemic also affected how Russian citizens feel about their government? To explore how the pandemic has affected political support in Russia, we analyzed data from a representative online panel survey, “Values in Crisis,” carried out by the Laboratory for Comparative Social Research at the Higher School of Economics (LCSR, HSE). We looked at four indicators of support: confidence in (1) the Russian government, (2) the health sector, and (3) the country’s institutions as a whole, as well as respondents’ opinions on (4) how well the government is handling the coronavirus crisis. We found that actual encounters with COVID-19 and the public healthcare system are negatively, although weakly, associated with all four indicators. We also found that the fear of getting sick moderately positively correlates with assessments of the government’s response to the crisis. Reported negative economic impacts do not seem to affect political trust and support. Strikingly, the most distrusting group of respondents are the so-called “COVID19-dissidents,” who consistently scored low on all measures due to their refusal to take COVID-19 seriously

Robust dynamic schedule coordination control in the supply chain

International audienceCoordination plays crucial role in supply chain management. In this paper, we extend the existing body of literature on supply chain coordination by representing a robust schedule coordination approach. A hybrid discrete/continuous flow shop supply chain with job shop processes at each supplier stage is studied. For this purpose, the developed scheduling model comprises operations control (for customer order fulfillment dynamics), channel control (production machine and transportation dynamics), resource control (material supply dynamics), and flow control (processing and shipment dynamics) with multiple objectives. Based on the scheduling model, we introduce a robust analysis of schedule coordination in the presence of disruptions in capacities and supply. The application of attainable sets opens a possibility to analyse schedule coordination dynamics under disruptions. The results provide insights of how to integrate the coordination issues into schedule robustness analysis. We exemplify the developed approach for the case of two-stage supply chain coordination, and derive managerial insights for both considered scheduling problem and application of dynamic control methods to supply chain coordination in general

Optimal Control Algorithms and Their Analysis for Short-Term Scheduling in Manufacturing Systems

International audienceCurrent literature presents optimal control computational algorithms with regard to state, control, and conjunctive variable spaces. This paper first analyses the advantages and limitations of different optimal control computational methods and algorithms which can be used for short-term scheduling. Second, it develops an optimal control computational algorithm that allows for the solution of short-term scheduling in an optimal manner. Moreover, qualitative and quantitative analysis of the manufacturing system scheduling problem is presented. Results highlight computer experiments with a scheduling software prototype as well as potential future research avenues

Socio-Demographic Profiles, Personality Traits, Values, and Attitudes of COVID-Skeptics in Russia

In this study, we explore how various socio-demographic attributes, personality traits, values, and attitudes of COVID-19 skeptics differ from those of the rest of the Russian population. We use data collected during the first round of the international online panel survey “Values in Crisis” (in short ViC; fieldwork mid-June 2020, N = 1527). We operationalize COVID-skepticism as support for the idea that the COVID-19 pandemic is a hoax and that all the lockdown measures are a hysterical overreaction, indicated by 38% of our respondents. Basic descriptive tests show that male, middle-aged, and less educated respondents are more likely to express skeptical views of the pandemic. The direct experience of the disease, quite predictably, decreases the likelihood of being coronaskeptic, whereas encountering negative economic consequences of the pandemic has the reverse effect. Interestingly, no systematic differences between skeptics and non-skeptics in the “Big-5” personality traits are visible in our data. At the same time, the coronaskeptic group has consistently lower scores on Schwarz’s conservation values and higher scores on openness to change values. COVID-19 skeptics also tend to oppose globalization, international cooperation, and migration. They are slightly less trusting of other people and traditional media, less proud of being Russian citizens, but do not differ from non-skeptics in terms of religiosity. Perhaps the most striking finding is that this group demonstrates much lower levels of confidence in government, health system, and national institutions, and also evaluates the government’s performance in handling the COVID-19 crisis much more critically.Peer reviewe

Emergent entanglement structures and self-similarity in quantum spin chains

We introduce an experimentally accessible network representation for many-body quantum states based on entanglement between all pairs of its constituents. We illustrate the power of this representation by applying it to a paradigmatic spin chain model, the XX model, and showing that it brings to light new phenomena. The analysis of these entanglement networks reveals that the gradual establishment of quasi-long range order is accompanied by a symmetry regarding single-spin concurrence distributions, as well as by instabilities in the network topology. Moreover, we identify the existence of emergent entanglement structures, spatially localised communities enforced by the global symmetry of the system that can be revealed by model-agnostic community detection algorithms. The network representation further unveils the existence of structural classes and a cyclic self-similarity in the state, which we conjecture to be intimately linked to the community structure. Our results demonstrate that the use of tools and concepts from complex network theory enables the discovery, understanding, and description of new physical phenomena even in models studied for decades

Emergent entanglement structures and self-similarity in quantum spin chains

We introduce an experimentally accessible network representation for many-body quantum states based on entanglement between all pairs of its constituents. We illustrate the power of this representation by applying it to a paradigmatic spin chain model, the XX model, and showing that it brings to light new phenomena. The analysis of these entanglement networks reveals that the gradual establishment of quasi-long range order is accompanied by a symmetry regarding single-spin concurrence distributions, as well as by instabilities in the network topology. Moreover, we identify the existence of emergent entanglement structures, spatially localized communities enforced by the global symmetry of the system that can be revealed by model-agnostic community detection algorithms. The network representation further unveils the existence of structural classes and a cyclic self-similarity in the state, which we conjecture to be intimately linked to the community structure. Our results demonstrate that the use of tools and concepts from complex network theory enables the discovery, understanding and description of new physical phenomena even in models studied for decades.This article is part of the theme issue 'Emergent phenomena in complex physical and socio-technical systems: from cells to societies'.Peer reviewe

NONLINEAR ANALYSIS OF STATICALLY INDETERMINATE WOODEN STRUCTURES AND OPTIMIZATION OF CROSS SECTION DIMENSIONS OF DOME RIBS

The analysis of the behaviour of natural structures of laminated wood domes and the numerous preliminary calculations have shown the possibility of saving materials by reducing the height of cross sections of meridional ribs. This is especially effective when you include in design of skins, performing a role of building shell, the collaboration with frame elements (annular and longitudinal ribs). Multiple static indeterminacy of such structure allows its non-linear work and the redistribution of forces under nonuniform loads. At the same ime, the skin carries a significant part of the forces appearing in the shell and the ribs are underloaded. The tress-strain states of all elements are investigated. For the frame analysis the calculation is performed by the method of integral module that allows controlling strength resistance of a structure at any moment of its operation. The design recommendations for section dimensions of a shell are developed