Anderson Molecules

Atoms can form molecules if they attract each other. Here, we show that atoms are also able to form bound states not due to the attractive interaction but because of destructive interference. If the interaction potential changes in a disordered way with a change of the distance between two atoms, Anderson localization can lead to the formation of exponentially localized bound states. While disordered interaction potentials do not exist in nature, we show that they can be created by means of random modulation in time of the strength of the original interaction potential between atoms and objects that we dub Anderson molecules can be realized in the laboratory.Comment: 13 pages, 5 figures, references added and minor correction

Molecular modelling of odd viscoelastic fluids

We consider an active, stochastic microscopic model of particles suspended in a fluid and show that the coarse-grained description of this model renders odd viscoelasticity. The model is made up of odd dumbbells, each featuring a robotic device as the bead, which exhibits a particular torque response. We analytically compute the stress-stress correlator and corroborate the results using molecular dynamics simulations. We also provide a unified analytical framework for several experimental and numerical setups designed to elucidate odd effects in fluids.Comment: 17 pages, 7 figure

Examining the generalizability of research findings from archival data

This initiative examined systematically the extent to which a large set of archival research findings generalizes across contexts. We repeated the key analyses for 29 original strategic management effects in the same context (direct reproduction) as well as in 52 novel time periods and geographies; 45% of the reproductions returned results matching the original reports together with 55% of tests in different spans of years and 40% of tests in novel geographies. Some original findings were associated with multiple new tests. Reproducibility was the best predictor of generalizability—for the findings that proved directly reproducible, 84% emerged in other available time periods and 57% emerged in other geographies. Overall, only limited empirical evidence emerged for context sensitivity. In a forecasting survey, independent scientists were able to anticipate which effects would find support in tests in new samples

Molekuły Andersona

W niniejszej pracy analizujemy, jak periodyczne zaburzanie układu poruszających się atomów może być wykorzystane do konstruowania różnego rodzaju efektywnych oddziaływań. W szczególności pokazujemy, jak wytworzyć stan związany atomów dzięki obecności nieporządku w układzie i zjawisku lokalizacji Andersona. Taki stan może być nazwany "molekułą Andersona".In this thesis we study how by periodically perturbing a system of moving atoms one can engineer various kinds of effective interactions. In particular we show how to create a bound state of atoms by relying on the presence of disorder in the system and the phenomenon of Anderson localization. Such a state can be called an "Anderson molecule"

Periodically perturbed systems and their relation to time crystals

Dyskretne kryształy czasowe to układy wielu ciał, które, poddane periodycznemu zaburzeniu, rozpoczynają ruch z okresem innym niż okres zaburzenia. W ten sposób łamią one dyskretną symetrię względem przesunięcia w czasie, jaką posiada hamiltonian. W niniejszej pracy bada się zachowanie cząstek, które poruszają się w polu grawitacyjnym i odbijają od drgającego podłoża, będąc z tym podłożem w rezonansie typu (2s+1):2. Przeprowadzona została dokładna analiza klasyczna ruchu cząstki w pobliżu rezonansów, której wynikiem jest wyprowadzenie efektywnego hamiltonianu opisującego ten ruch. Poczyniono też pierwsze kroki w stronę pełnego kwantowomechanicznego opisu poprzez znalezienie stanów Floquet związanych z rezonansami. Praca ta daje podstawę do dalszego badania hipotezy mówiącej, że w tym układzie może zachodzić złamanie dyskretnej symetrii translacyjnej w czasie w taki sposób, że nowy okres ruchu byłby niecałkowitą wielokrotnością okresu podstawowego, co potencjalnie może doprowadzić do odkrycia nowej klasy kryształów czasowych.Discrete time crystals are many-body systems which, when subjected to a periodic perturbation, begin to move with a period different then the period of driving. This way the discrete time symmetry of the hamiltonian is broken. In this thesis, a behaviour of particles moving in a gravitational field and bouncing on an oscillating ground is investigated in the case, when the particles are in a (2s+1):2-type resonance with the ground. A precise classical analysis of the particle's motion in the vicinity of the resonances has been performed, resulting in derivation of an effective hamiltonian governing this motion. The first steps towards a full quantum-mechanical description have also been made with indentification of Floquet states associated with the resonances. The thesis paves the way for further examination of the hypothesis stating that in this system a discrete time symmetry breaking could be observed, where the new period of motion would be a non-integer multiplicity of the basic period, which may potentially lead to a discovery of a new class of time crystals

Cenospheres-Reinforced PA-12 Composite: Preparation, Physicochemical Properties, and Soaking Tests

The main aim of this research was the preparation of a polymer–ceramic composite with PA-12 as the polymer matrix and modified aluminosilicate cenospheres (CSs) as the ceramic filler. The CSs were subjected to an early purification and cleaning process, which was also taken as a second objective. The CSs were surface modified by a two-step process: (1) etching in Piranha solution and (2) silanization in 3-aminopropyltriethoxysilane. The composite was made for 3D printing by FDM. Raw and modified CSs and a composite with PA-12 were subjected to the following tests: surface development including pores (BET), real density (HP), chemical composition and morphology (SEM/EDS, FTIR), grain analysis (PSD), phase composition (XRD), hardness (HV), and static tensile tests. The composites were subjected to soaking under simulated body fluid (SBF) conditions in artificial saliva for 14, 21, and 29 days. Compared to pure PA-12, PA-12_CS had generally better mechanical properties and was more resistant to SBF at elevated temperatures and soaking times. These results showed this material has potential for use in biomedical applications. These results also showed the necessity of developing a kinetic aging model for aging in different liquids to verify the true value of this material