Experimental detection of entanglement via witness operators and local measurements

Abstract

In this paper we address the problem of detection of entanglement using only few local measurements when some knowledge about the state is given. The idea is based on an optimized decomposition of witness operators into local operators. We discuss two possible ways of optimizing this local decomposition. We present several analytical results and estimates for optimized detection strategies for NPT states of 2 × 2 and N × M systems, entangled states in 3 qubit systems, and bound entangled states in 3 × 3 and 2 × 4 systems.     

New schemes for creating large optical Schrödinger cat states using strong laser fields

Recently, using conditioning approaches on the high-harmonic generation process induced by intense laser-atom interactions, we have developed a new method for the generation of optical Schrödinger cat states (Lewenstein et al. in Nat Phys, 17 1104–1108, 2021. https://doi/10.1038/s41567-021-01317-w). These quantum optical states have been proven to be very manageable as, by modifying the conditions under which harmonics are generated, one can interplay between kitten and genuine cat states. Here, we demonstrate that this method can also be used for the development of new schemes towards the creation of optical Schrödinger cat states, consisting of the superposition of three distinct coherent states. Apart from the interest these kind of states have on their own, we additionally propose a scheme for using them towards the generation of large cat states involving the sum of two different coherent states. The quantum properties of the obtained superpositions aim to significantly increase the applicability of optical Schrödinger cat states for quantum technology and quantum information processing.

     

Real Two Dimensional Scaled Matching

Scaled Matching refers to the problem of finding all locations in the text where the pattern, proportionally enlarged according to an arbitrary real-sized scale, appears. Scaled matching is an important problem that was originally inspired by Computer Vision. Finding a combinatorial definition that captures the concept of real scaling in discrete images has been a challenge in the pattern matching field. No definition existed that captured the concept of real scaling in discrete images, without assuming an underlying continuous signal, as done in the image processing field. We present a combinatorial definition for real scaled matching that scales images in a pleasing natural manner. We also present efficient algorithms for real scaled matching. The running times of our algorithms are as follows. For T, a two-dimensional n×n text array, and P, an m×m pattern array, we find in T all occurrences of P scaled to any real value in time O(nm ³+n ² mlog m). Research of A. Amir partially supported by ISF grant 282/01 and NSF grant CCR-01-04494.     

ClassSTRONG: Classical simulations of strong field processes

A set of Mathematica functions is presented to model classically two of the most important processes in strong field physics, namely high-order harmonic generation (HHG) and above-threshold ionization (ATI). Our approach is based on the numerical solution of the Newton–Lorentz equation of an electron moving on an electric field and takes advantage of the symbolic languages features and graphical power of Mathematica. Like in the Strong Field Approximation (SFA), the effects of atomic potential on the motion of electron in the laser field are neglected. The SFA was proven to be an essential tool in strong field physics in the sense that it is able to predict with great precision the harmonic (in the HHG) and energy (in the ATI) limits. We have extended substantially the conventional classical simulations, where the electric field is only dependent on time, including spatial nonhomogeneous fields and spatial and temporal synthesized fields. Spatial nonhomogeneous fields appear when metal nanosystems interact with strong and short laser pulses and temporal synthesized fields are routinely generated in attosecond laboratories around the world. Temporal and spatial synthesized fields have received special attention nowadays because they would allow to exceed considerably the conventional harmonic and electron energy frontiers. Classical simulations are an invaluable tool to explore exhaustively the parameters domain at a cheap computational cost, before massive quantum mechanical calculations, absolutely indispensable for the detailed analysis, are performed.     

发展中国家公众对科学研究的理解

在发达国家关于“科学素养”的讨论中,大众科学知识的核心通常是指科学家定义的物理学、化学、生物学等。2002年12月在南非开普敦举行的研讨会上,研究人员和实践者认为,发展中国家的公众对研究的理解更多地与一些基本问题相关为公众提供清洁的饮用水、让公众了解未采取安全措施的性生活与艾滋病毒感染之间的必然联系等等。发展中国家促进公众对研究的理解的各种项目必须面向弱势群体,必须努力消除社会阶层与地域间的不平等。科学技术资源的分配在政策上不应无视差别地一概而论。     

Massive ascites associated wth endometriosis

Massive ascites associated with pelvic endometriosis is an unusual occurrence. Two cases recently encountered by the authors are presented, and 7 additional cases from the literature are reviewed. Clinical courses and operative findings are described, and the management of the cases is presented. The etiology of ascites is explored and the possibility of conservative surgery and hormonal control with danazol is discussed.