Finite-dimensional states and entanglement generation for a nonlinear coupler

We discuss a system comprising two nonlinear (Kerr-like) oscillators coupled mutually by a nonlinear interaction. The system is excited by an external coherent field that is resonant to the frequency of one of the oscillators. We show that the coupler evolution can be closed within a finite set of $n$-photon states, analogously as in the \textit{nonlinear quantum scissors} model. Moreover, for this type of evolution our system can be treated as a \textit{Bell-like states} generator. Thanks to the nonlinear nature of both: oscillators and their internal coupling, these states can be generated even if the system exhibits its energy dissipating nature, contrary to systems with linear couplings.Comment: Accepted for publication in Physical Review

Sudden Death and Birth of Entanglement Effects for Kerr-Nonlinear Coupler

We analyse the entanglement dynamics in a nonlinear Kerr-like coupler interacting with external environment. Whenever the reservoir is in a thermal vacuum state the entanglement (measured by concurrence for a two-qubit system) exhibits regular oscillations of decreasing amplitude. In contrast, for thermal reservoirs we can observe dark periods in concurrence oscillations (which can be called a "sudden death" of the entanglement) and the entanglement rebuild (which can be named the "sudden birth" of entanglement). We show that these features can be observed when we deal with 2-qubit system as well as $2\otimes 3$ system.Comment: 18 pages including 7 figures. Journal of the Optical Society of America B - in pres

Lung and Intercostal Upper Abdomen Ultrasonography for Staging Patients with Ovarian Cancer: A Method Description and Feasibility Study

A detailed transabdominal and transvaginal ultrasound examination, performed by an expert examiner, could render a similar diagnostic performance to computed tomography for assessing pelvic/abdominal tumor spread disease in women with epithelial ovarian cancer (EOC). This study aimed to describe and assess the feasibility of lung and intercostal upper abdomen ultrasonography as pretreatment imaging of EOC metastases of supradiaphragmatic and subdiaphragmatic areas. A preoperative ultrasound examination of consecutive patients suspected of having EOC was prospectively performed using transvaginal, transabdominal, and intercostal lung and upper abdomen ultrasonography. A surgical-pathological examination was the reference standard to ultrasonography. Among 77 patients with histologically proven EOC, supradiaphragmatic disease was detected in 13 cases: pleural effusions on the right (n = 12) and left (n = 8) sides, nodular lesions on diaphragmatic pleura (n = 9), focal lesion in lung parenchyma (n = 1), and enlarged cardiophrenic lymph nodes (n = 1). Performance (described with area under the curve) of combined transabdominal and intercostal upper abdomen ultrasonography for subdiaphragmatic areas (n = 77) included the right and left diaphragm peritoneum (0.754 and 0.575 respectively), spleen hilum (0.924), hepatic hilum (0.701), and liver and spleen parenchyma (0.993 and 1.0 respectively). It was not possible to evaluate the performance of lung ultrasonography for supradiaphragmatic disease because only some patients had this region surgically explored. Preoperative lung and intercostal upper abdomen ultrasonography performed in patients with EOC can add valuable information for supradiaphragmatic and subdiaphragmatic regions. A reliable reference standard to test method performance is an area of future research. A multidisciplinary approach to ovarian cancer utilizing lung ultrasonography may assist in clinical decision-making.info:eu-repo/semantics/publishedVersio

Long-time fidelity and chaos for a kicked nonlinear oscillator system

We deal with a system comprising a nonlinear (Kerr-like) oscillator excited by a series of ultra-short external pulses. We introduce the fidelity-based entropic parameter that can be used as an indicator of quantum chaos. Moreover, we propose to use the fidelity-like parameter comprising the information about the mean number of photons in the system. We shall concentrate on the long-time behaviour of the parameters discussed, showing that for deep chaos cases the quantum fidelities behave chaotically in the classical sense despite their strictly quantum character.Comment: 20 pages including 8 figure