Spectroscopic shifts as a signature of many-body localization phase transition in a one-dimensional transmon array

Abstract. Many-body localization is a phase of matter, which can occur in systems with strong disorder and interactions. One of the main characteristics of the many-body localized phase is that it cannot thermalize because localization slows or stops the propagation of information inside the system. Here, we study many-body localization in a one-dimensional transmon qubit array theoretically and numerically. Differing from frequently used approaches to many-body localization, we study the dynamical phase transition between a thermalized phase and the many-body localized phase by using a numerical method that is based on Fermi’s golden rule. This method makes it possible to distinguish the thermalized phase from the many-body localized phase and allows one to estimate how much disorder is required for the many-body localization phase transition. The distinction between the phases is made by a “soft” gap which appears at the zero-frequency and is known as a universal sign of localization. Unlike many other methods, which are used to recognize the many-body localized phase, the method in question can be easily applied to experiments. In the system that we have chosen the transmon qubits are capacitively coupled to each other, and the system is driven by a harmonic external magnetic flux that induces transitions between the energy eigenstates of the system. We calculated the numerical results for a system with eight transmon qubits, and to make calculations simpler, we assumed that the temperature of the system is infinite. The size of the system is limited by the computational expensiveness of our method. Somewhat surprisingly, the most laborious part of the calculations proved to be the Fermi’s golden rule, which is used to calculate the transition rate spectrum. The results show that the method in question can distinguish the many-body localized phase if the strength of disorder in the system is large, but near the many-body localized phase transition, it is challenging to observe the difference between the thermalized phase and the many-body localized phase. We calculated the transition rate spectra using different values of on-site interaction strength. The results show us that the disorder strength needed for the phase transition is smaller if the on-site interaction strength is weak or very strong. Lastly, we demonstrated the many-body localization phase transition by calculating the energy eigenstates as a function of disorder strength and observing how strongly the eigenenergies repel each other. This method proved to be relatively imprecise to specify the critical disorder strength needed for the many-body localized phase. However, one can clearly notice that the repulsion between energy levels grows weaker as the disorder strength grows stronger

Bohl-Perron type stability theorems for linear difference equations with infinite delay

Relation between two properties of linear difference equations with infinite delay is investigated: (i) exponential stability, (ii) \l^p-input \l^q-state stability (sometimes is called Perron's property). The latter means that solutions of the non-homogeneous equation with zero initial data belong to \l^q when non-homogeneous terms are in \l^p. It is assumed that at each moment the prehistory (the sequence of preceding states) belongs to some weighted \l^r-space with an exponentially fading weight (the phase space). Our main result states that (i) $\Leftrightarrow$ (ii) whenever $(p,q) \neq (1,\infty)$ and a certain boundedness condition on coefficients is fulfilled. This condition is sharp and ensures that, to some extent, exponential and \l^p-input \l^q-state stabilities does not depend on the choice of a phase space and parameters $p$ and $q$, respectively. \l^1-input \l^\infty-state stability corresponds to uniform stability. We provide some evidence that similar criteria should not be expected for non-fading memory spaces.Comment: To be published in Journal of Difference Equations and Application

Multimode physics of the unimon circuit

We consider a superconducting half-wavelength resonator that is grounded at its both ends and contains a single Josephson junction. Previously this circuit was considered as a unimon qubit in the single-mode approximation where dc-phase-biasing the junction to $\pi$ leads to increased anharmonicity and 99.9% experimentally observed single-qubit gate fidelity. Inspired by the promising first experimental results, we develop here a theoretical and numerical model for the detailed understanding of the multimode physics of the unimon circuit. To this end, first, we consider the high-frequency modes of the unimon circuit and find that even though these modes are at their ground state, they imply a significant renormalization to the Josephson energy. We introduce an efficient method how the relevant modes can be fully taken into account and show that unexcited high-lying modes lead to corrections in the qubit energy and anharmonicity. Interestingly, provided that the junction is offset from the middle of the circuit, we find strong cross-Kerr coupling strengths between a few low-lying modes. This observation paves the way for the utilization of the multimode structure, for example, as several qubits embedded into a single unimon circuit

Clinical and functional implications of kidney in patients with hepatic impairment

Departamentul Medicină Internă, Clinica Medicală nr. 1, Disciplina Sinteze clinice, Secţia nefrologie, IMSP SCM „Sfânta Treime" or. Chişinău, Al VI-lea Congres de Urologie, Dializă şi Transplant Renal din Republica Moldova cu participare internaţională (21-23 octombrie 2015)Rezumat Mecanismele care influenţează apariţia complicaţiilor renale la pacienţii cu ciroză hepatică sunt în continuare incomplet elucidate, determinând pronosticul nefavorabil al afecţiunii hepatice. Modificările de eliberare endogenă a prostaglandinelor renale, disfuncţia endotelială, semnificaţia lor în procesele complexe, prin care participă la modularea fluxului sanguin intrarenal la pacienţii cu afectare hepatică continuă să fie subiectul unor discuţii contradictorii. Subiectul cercetării prezentate a fost determinarea substanţelor vazoactive în serul sanguin la bolnavii cu ciroză hepatică clasa Child-Pugh A, B şi C, la pacienţii cu hipertensiune portală şi varice esofagiene (VE), ascită, encefalopatie hepatică (EH) şi în prezenţa factorilor de risc, care pot precipita complicaţiile renale şi analiza rezultatelor obţinute.Summary The mechanisms that influence renal complications in patients with liver cirrhosis remain incompletely understood, causing unfavorable prognosis of liver disease. Changes of endogenous prostaglandin renal release, endothelial dysfunction, their significance in modulating renal blood flow in patients with hepatic impairment continues to be the subject of contradictory discussions. The determination of these vazoactive agents in patients with liver cirrhosis Child-Pugh class A, B and C, in patients with portal hypertension and esophageal varices, in ascites, hepatic encephalopathy and the risk factors that can precipitate kidney complications, the evaluation of obtained results was the subject of the research

The estimation of renal vasoconstrictive and vasodilatative agents activity in patients with liver cihrrosis

Catedra de Medicină Internă N 5 USMF,,Nicolae Testemiţanu”The mechanisms leading to altered renal blood flow and renal function in patients with liver cirrhosis are not entirely clear. Renal vasoconstriction is believed to be secondary to a reduction in effective arterial volume in severe cirrhosis. Vasoconstrictive activation of Endotelin- 1 , the role of Prostaglandin E -2 in regulation of renal blood flow were evaluated at 80 patients with liver cirrhosis, recruited into groups.The results show the vasoconstrictive effect of Endotelin-1 with it significantly increased level and the inhibited levels of Prostaglandin E 2 in decompensated cirrhosis produces negative effects on renal blood flow. Mortalitatea în rezultatul disfuncţiilor renale este crescută substanţial, variind de la 50%-70% în cazul IRA din necroză tubulară acută la 75%-100% din motiv de SHR. Astfel depistarea precoce a tulburăilor funcţionale renale are o importanţă predictivă majoră în managmentul pacienţilor cu ciroză hepatică. Sensibilitatea rinichiului la modificările hemodinamice şi la intervenţia toxinelor se manifestă prin creşerea activităţii agenţilor vasoconstrictori şi reducerea activităţii factorilor vasodilatatori la nivelul circulaţiei renale. Elucidarea modificărilor de eliberare endogenă a prostaglandinelor renale (PGE-2 ) şi a endotelinei 1 ( ET -1) ar contribui la elaborarea unor scheme moderne de prevenire şi tratament medicamentos al perturbărilor funcţionale renale în ciroza hepatică. Determinarea ET-1 şi a PGE-2 în ser , efectuată prin metoda imunoenzimatică ELISA la 80 pacienţi tinde să elucideze aspectele perturbărilor vasculare renale la pacienţii cu ciroză hepatică

Instalarea complicaţiilor renale la pacienţii cu ciroze hepatice: aspecte fiziopatologice

Conferinţa naţională în medicina internă din Republica Moldova cu participare internaţională, 19-20 mai 2011, Chişinău, Republica MoldovaSummary. Vasoconstrictive effect of Endotelin-1 (ET- 1), the role of Prostaglandin E-2 (PGE-2) in regulation of renal blood flow were evaluated at 82 patients with liver cirrhosis. The results show the vasoconstrictive effect of ET-1 with it significantly increased level and the inhibited levels of PGE-2 in decompensated cirrhosis, that produce negative effects on renal blood flow.Actualitate. Perfuzia renală compromisă determină sensibilitatea rinichiului la modificările hemodinamice şi la intervenţia toxinelor, manifestându- se prin modificarea activităţii agenţilor vasoconstrictori şi vasodilatatori la nivelul circulaţiei renale. Elucidarea modificărilor de eliberare endogenă a prostaglandinelor renale şi contribuţia ET-1 la instalarea tulburărilor hemodinamicii renale la pacienţii cu ciroză hepatică necesită studii suplimentare. Scopul lucrării: estimarea valorilor serice ale PGE-2 şi ET-1 la pacienţii cu ciroză hepatică, cu scopul de a elabora scheme moderne de prevenire şi tratament medicamentos al perturbărilor funcţionale renale în ciroza hepatică. Materiale şi metode. Au fost luaţi în studiu 82 de pacienţi cu ciroză hepatică clasele Child-Pugh A, B, C (vârsta medie de 51,5±1,56 ani), inclusiv 12 pacienţi diagnosticaţi cu SHR. ET-1 şi PGE-2 în ser au fost determinate prin metoda imunoenzimatică ELISA. Rezultate. S-a constatat că valorile PGE-2, comparativ cu grupul de control, scad odată cu avansarea cirozei hepatice, când perfuzia renală este compromisă, efectul vasodilatator al PGE-2 se micşorează semnificativ. Scăderea ratei de filtraţie glomerulară se asociază cu creşterea valorii ET-1, cu hiponatriemia, scăderea răspunsului la diuretice şi instalarea edemelor refractare la tratament diuretic. Concluzii. Sinteza PGE-2 în rinichi este inhibată de perturbările hemodinamice renale odată cu avansarea cirozei hepatice, ceea ce se manifestă prin micşorarea valorilor PGE-2 în ser. Se constată creşterea valorilor ET-1 ca cel mai marcat vasoconstrictor cunoscut la pacienţii cu ciroză hepatică clasa Child–Pugh C. Scăderea ratei de filtrare glomerulară se asociază cu creşterea valorii ET-1, hiponatriemie, prezenţa edemelor refractare la pacienţii cu ascită marcată

Оценка патогенетических факторов, влияющих на почечные осложнения у больных циррозом печени

Catedra de Medicină Internă nr. 5, USMF „Nicolae Testemiţanu”, Conferinţa Ştiinţifico-Practică „Medicina modernă, actualităţi şi perspective”, consacrată aniversării de 40 de ani ai Spitalului Clinic al Ministerului Sănătăţii, 27-28 mai, 2010, Chişinău, Republica MoldovaThe study involved 82 patients - 40 women and 42 men. Early detection of renal function impairment is a major predictive importance in managing patients with liver cirrhosis. In liver cirrhosis Child-Pugh class C, the renal hemodynamics is already compromised and is characterized by growth of vasoconstrictor factors. Azotemia in acute renal failure in hepato-renal syndrome does not reach very high values and is not associated with severe hyperpotassemia. PGE2 synthesis in the kidney is progressively inhibited by renal hemodynamic disturbances with advancing liver cirrhosis, which translates into decreasing PGE-1 levels in the serum. E1 is the vasoconstrictor with the most increased levels in patients with liver cirrhosis Child-Pugh class C and particularly in patients with hepato-renal syndrome. The decreased glomerular filtration rate is associated with an increased amount of ET-1, low sodium in the blood and edema in patients with refractory ascites. В исследовании включены 82 больных - 40 женщин и 42 мужчины. Раннее обнаружение почечной недостаточности является одним из основных прогностических факторов в менеджменте больных циррозом печени. При циррозе печени класса C по ChildPugh почечная гемодинамика уже скомпрометирована и характеризуется ростом сосудосуживающих факторов при отсутствии роста показателей эндогенных креатинина и мочевины в сыворотке крови. Азотемия в острой почечной недостаточности при печеночнопочечном синдроме не достигает больших значений и не связана с выраженной гиперкалиемией. Синтез PGE2 в почках постепенно замедляется из-за нарушения почечной гемодинамики при прогрессировании цирроза печени. У больных циррозом печени класса С по Child-Pugh, особенно при наличии печеночно-почечного синдрома, выявляется повышенная концентрация сосудосуживающего фактора Е1. Снижение скорости клубочковой фильтрации ассоциируется с повышенным содержанием ЕТ-1, низким содержанием натрия крови и с отеками

Intelligent Air Pollution Sensors Calibration for Extreme Events and Drifts Monitoring

Air quality low-cost sensors are affordable and can be deployed in massive scale in order to enable high-resolution spatio-temporal air pollution information. However, they often suffer from sensing accuracy, in particular when they are used for capturing extreme events. We propose an intelligent sensors calibration method that facilitates correcting low-cost sensors' measurements accurately and detecting the calibrators' drift. The proposed calibration method uses Bayesian framework to establish white-box and black-box calibrators. We evaluate the method in a controlled experiment under different types of smoking events. The calibration results show that the method accurately estimates the aerosol mass concentration during the smoking events. We show that black-box calibrators are more accurate than white-box calibrators. However, black-box calibrators may drift easily when a new smoking event occurs, while white-box calibrators remain robust. Therefore, we implement both of the calibrators in parallel to extract both calibrators' strengths and also enable drifting monitoring for calibration models. We also discuss that our method is implementable for other types of low-cost sensors suffered from sensing accuracy.Peer reviewe

Carbon dynamics, net primary productivity (NPP) and human appropriated NPP (HANPP) across a forest‐cocoa farm landscape in West Africa

Terrestrial net primary productivity (NPP) is an important metric of ecosystem functioning; however, there is little empirical data on the NPP of human-modified ecosystems, particularly smallholder,perennial crops like cocoa (Theobroma cacao), which are extensive across the tropics. Human appropriated NPP (HANPP) is a measure of the proportion of a natural system’s NPP that has either been reduced through land-use change or harvested directly and, previously, has been calculated to estimate the scale of the human impact on the biosphere. Additionally, human-modification can create shifts in NPP allocation and decomposition, with concomitant impacts on the carbon cycle. This study presents the results of three years of intensive monitoring of forest and smallholder cocoa farms across disturbance, management intensity, distance from forest and farm age gradients. We measured among the highest reported NPP values in tropical forest, 17.57 ± 2.1 and 17.7 ± 1.6 Mg C ha-1 yr-1 for intact and logged forest respectively; however, the average NPP of cocoa farms was still higher, 18.8 ± 2.5 Mg C ha-1 yr-1, which we found was driven by cocoa pod production. We found a dramatic shift in litterfall residence times, where cocoa leaves decomposed more slowly than forest leaves and shade tree litterfall decomposed considerably faster, indicating significant changes in rates of nutrient cycling. The average HANPP value for all cocoa farms was 2.1 ± 1.1 Mg C ha-1 yr-1; however, depending on the density of shade trees it ranged from -4.6 to 5.2 Mg C ha-1 yr-1. Therefore, rather than being related to cocoa yield, HANPP was reduced by maintaining higher shade levels. Across our monitored farms 18.9% of farm NPP was harvested (i.e. whole cocoa pods) and only 1.1% (i.e.cocoa beans) was removed from the system; suggesting that the scale of HANPP in smallholder cocoa agroforestry systems is relatively small