Inter-qubit interaction mediated by collective modes in a linear array of three-dimensional cavities

A design of LEGO-like construction set that allows assembling of different linear arrays of three-dimensional (3D) cavities and qubits for circuit quantum electrodynamics experiments has been developed. A study of electromagnetic properties of qubit-3D cavity arrays has been done by using high frequency structure simulator (HFSS). A technique for estimation of inter-qubit coupling strength between qubits embedded in different cavities of cavity array, which combines Hamiltonian description of the system with simple HFSS simulations, has been proposed. A good agreement between inter-qubit coupling strengths, which were obtained by using this technique and directly from simulation, demonstrates the suitability of the method for more complex qubit–cavity arrays where usage of finite-element electromagnetic simulators is limited

The virgin forests of the Synevyr National Nature Park, Ukraine: its current condition and biodiversity

Among the protected sites of the Eastern Carpathians, the Synevyr National Nature Park (NNP) in the Zakarpattia region of Ukraine is one of the most valuable and was created to preserve its unique mountain beech and spruce forest communities. The importance of the conservation of typical natural virgin forest ecosystems of the Central European mountain systemis emphasized. The aim of this article was to determine the state of the naturalness of virgin forests in the territory of Synevyr NNP, to analyse their syntaxonomy, and to establish the floristic and geobotanical characteristics of its virgin forests and to distinguish the existing biodiversity threats. It was established that the studied plots of beech and spruce forests within the territory of the Synevyr NNP have a distinct virgin nature based on their structure, forest valuation parameters, spontaneous dynamics and other features. Syntaxonomically the virgin forests of the park belong to two associations: Symphyto cordati-Fagetum Vida (1959) 1963 (alliance Fagion sylvaticae Luquet 1926, order Fagetalia sylvaticae Pawłowski 1928, class Сarpino-Fagetea sylvaticae Jakucs ex Passarge 1968) and Luzulo luzuloidis-Fagetum (Du Rietz 1923) Markgraf 1932 (alliance Luzulo-Fagion sylvaticae Lohmeyer & Tx. in Tx. 1954, order Luzulo-Fagetalia Scamoni & Passarge 1959, class Quercetea roboripetraeae Br.-Bl. & Tx. ex Oberd. 1957). The natural and anthropogenic biodiversity threats of these virgin forests are summarized. The results of the research formed the basis for the inclusion of the beech virgin forests of Synevyr NNP as a UNESCO World Heritage Site in the list of objects on “Beech virgin forests and ancient forests of the Carpathians and other regions of Europe”

Alien Species in the Pioneer and Ruderal Vegetation of Ukraine

Invasions of nonnative plants are widely recognized as one of the major threats to the biodiversity of natural ecosystems on a global scale. Pioneer and ruderal habitats are the primary locations for the penetration of alien plants. Both pioneer and ruderal vegetation are very close in their genesis and beginning of development; therefore, a comparative analysis of their alien components and historical trends would contribute to clarifying the direction of successional changes and the possible management of destructive processes caused by anthropogenic influences in different types of habitats. The results of a structural and comparative analysis of the alien fractions of the coenofloras of the pioneer and ruderal vegetation of Ukraine indicated that the systematic, biomorphological, ecological, and geographical structures of these species show a high similarity, according to many of the main indicators, which allows them to successfully implement a strategy of invasion, particularly in communities characterized by instability and weak coenotic connections. It was established that the ecotopes of both types of vegetation are very favorable to the penetration and establishment of alien species; however, disturbed habitats of the ruderal type are more prone to invasions. In the communities of both pioneer and ruderal vegetation, alien species can become successfully established at the coenotic level, forming phytocoenoses of different hierarchical ranks. The results of this study will contribute to the identification of general patterns of invasions and the optimization (management) of disturbed and unstable natural ecosystems

Alien Species in the Pioneer and Ruderal Vegetation of Ukraine

Invasions of nonnative plants are widely recognized as one of the major threats to the biodiversity of natural ecosystems on a global scale. Pioneer and ruderal habitats are the primary locations for the penetration of alien plants. Both pioneer and ruderal vegetation are very close in their genesis and beginning of development; therefore, a comparative analysis of their alien components and historical trends would contribute to clarifying the direction of successional changes and the possible management of destructive processes caused by anthropogenic influences in different types of habitats. The results of a structural and comparative analysis of the alien fractions of the coenofloras of the pioneer and ruderal vegetation of Ukraine indicated that the systematic, biomorphological, ecological, and geographical structures of these species show a high similarity, according to many of the main indicators, which allows them to successfully implement a strategy of invasion, particularly in communities characterized by instability and weak coenotic connections. It was established that the ecotopes of both types of vegetation are very favorable to the penetration and establishment of alien species; however, disturbed habitats of the ruderal type are more prone to invasions. In the communities of both pioneer and ruderal vegetation, alien species can become successfully established at the coenotic level, forming phytocoenoses of different hierarchical ranks. The results of this study will contribute to the identification of general patterns of invasions and the optimization (management) of disturbed and unstable natural ecosystems

Optical amplification assisted by two-photon processes in a 3-level transmon artificial atom

We experimentally study interactions between two microwave fields mediated by 3-level transmon artificial atom with two-photon processes. The transmon has good selection rule, preventing one-photon transition, but allowing two-photon transition from ground state(0) to 2nd excited state(2). By pumping a control tone in resonance to the transition between 1st(1) and 2nd excited state(2), we control the one-photon transparency for 0 to 1 transition and two-photon transparency for 0 to 2 transition. The results are explained by the Autler-Townes splitting induced by the control microwave. In addition, two possible microwave amplification processes involving two-photon processes are also studied. The 4-wave mixing scheme increases the transmission by 3% while 2-photon optical pumping produces a 11% narrowband increment. All these phenomena can be operated with control and probe tones in a narrow band

Anthropogenic Transformations of Vegetation in the Kuyalnik Estuary Valley (Ukraine, Odesa District)

Human influence on the steppe ecosystems of Ukraine caused irreversible loss of biodiversity in the natural zone. Currently, this problem is aggravated by military operations which cover almost half of the steppe zone and are unprecedented in the entire history of their existence. This actualizes the study of vegetation dynamic processes under the influence of the novel anthropogenic factors, and serves as the scientific basis for restoring and preserving steppe vegetation and maintaining its functional stability. The paper highlights anthropogenic changes in vegetation of the Kuyalnik Estuary valley based on long-term comparative phytocenotic surveys and uses of the method of succession series for reconstruction. These changes are representative of the river valleys of the estuaries in the Northern Black Sea region. This work examines vegetation changes induced by runoff overregulation of estuary rivers within the basin, quarrying of sand and limestone, ploughing, grazing, burning, terracing of slopes and their afforestation, excessive mowing of grass stands, and uncontrolled recreation. Subject to the existing anthropogenic impact combined with global climate changes, further vegetation degradation was predicted to occur in the direction of xerophitization and halophitization, reduction in shrubby vegetation areas, degradation of steppe vegetation, and intensification of desertification processes

Anthropogenic Transformations of Vegetation in the Kuyalnik Estuary Valley (Ukraine, Odesa District)

Human influence on the steppe ecosystems of Ukraine caused irreversible loss of biodiversity in the natural zone. Currently, this problem is aggravated by military operations which cover almost half of the steppe zone and are unprecedented in the entire history of their existence. This actualizes the study of vegetation dynamic processes under the influence of the novel anthropogenic factors, and serves as the scientific basis for restoring and preserving steppe vegetation and maintaining its functional stability. The paper highlights anthropogenic changes in vegetation of the Kuyalnik Estuary valley based on long-term comparative phytocenotic surveys and uses of the method of succession series for reconstruction. These changes are representative of the river valleys of the estuaries in the Northern Black Sea region. This work examines vegetation changes induced by runoff overregulation of estuary rivers within the basin, quarrying of sand and limestone, ploughing, grazing, burning, terracing of slopes and their afforestation, excessive mowing of grass stands, and uncontrolled recreation. Subject to the existing anthropogenic impact combined with global climate changes, further vegetation degradation was predicted to occur in the direction of xerophitization and halophitization, reduction in shrubby vegetation areas, degradation of steppe vegetation, and intensification of desertification processes

Quantum simulation of the bosonic Kitaev chain

Superconducting quantum circuits are a natural platform for quantum simulations of a wide variety of important lattice models describing topological phenomena, spanning condensed matter and high-energy physics. One such model is the bosonic analog of the well-known fermionic Kitaev chain, a 1D tight-binding model with both nearest-neighbor hopping and pairing terms. Despite being fully Hermitian, the bosonic Kitaev chain exhibits a number of striking features associated with non-Hermitian systems, including chiral transport and a dramatic sensitivity to boundary conditions known as the non-Hermitian skin effect. Here, using a multimode superconducting parametric cavity, we implement the bosonic Kitaev chain in synthetic dimensions. The lattice sites are mapped to frequency modes of the cavity, and the in situ tunable complex hopping and pairing terms are created by parametric pumping at the mode-difference and mode-sum frequencies, respectively. We experimentally demonstrate important precursors of nontrivial topology and the non-Hermitian skin effect in the bosonic Kitaev chain, including chiral transport, quadrature wavefunction localization, and sensitivity to boundary conditions. Our experiment is an important first step towards exploring genuine many-body non-Hermitian quantum dynamics