Paddling mode of forward flight in insects

By analyzing high-speed video of the fruit fly, we discover a swimminglike mode of forward flight characterized by paddling wing motions. We develop a new aerodynamic analysis procedure to show that these insects generate drag-based thrust by slicing their wings forward at low angle of attack and pushing backwards at a higher angle. Reduced-order models and simulations reveal that the law for flight speed is determined by these wing motions but is insensitive to material properties of the fluid. Thus, paddling is as effective in air as in water and represents a common strategy for propulsion through aquatic and aerial environments.     

CW Cu II laser in a hollow anode-cathode discharge

CW laser operation on near infrared transitions of Cu II was investigated in a high voltage hollow cathode discharge tube of 19 cm active length. The high voltage was obtained by a special anode system placed inside the cathode. Threshold current for the strongest 7808 Å laser line was 0.4 A. At a discharge current of 2.4 A a multiline output power of 30 mW was obtained on six transitions between 7404 and 7896 Å.     

Approximative methods in the semiclassical theory of multiphoton processes

The present work aims at giving a theoretical background for the several theoretical methods existing in the literature describing multiphoton processes. Within the framework of the semiclassical theory a general expression for the multiphoton transition probability is given — using the formal time-dependent theory of scattering and the general properties of the Schrödinger equation of the problem. The amplitude of the multiphoton transition is a generalisation of the stationary transition operator for the non-stationary case. Using the general expression of the transition probability we compare the different non-perturbative approaches with the perturbation theory and establish the limits of their applicability.

     

Optical realization of optimal unambiguous discrimination for pure and mixed quantum states

Quantum mechanics forbids deterministic discrimination among nonorthogonal states. Nonetheless, the capability to distinguish nonorthogonal states unambiguously is an important primitive in quantum information processing. In this work, we experimentally implement generalized measurements in an optical system and demonstrate the first optimal unambiguous discrimination between three nonorthogonal states, with a success rate of 55%, to be compared with the 25% maximum achievable using projective measurements. Furthermore, we present the first realization of unambiguous discrimination between a pure state and a nonorthogonal mixed state.     

Universal programmable quantum state discriminator that is optimal for unambiguously distinguishing between unknown states

We construct a device that can unambiguously discriminate between two unknown quantum states. The unknown states are provided as inputs, or programs, for the program registers, and a third system, which is guaranteed to be prepared in one of the states stored in the program registers, is fed into the data register of the device. The device will then, with some probability of success, tell us whether the unknown state in the data register matches the state stored in the first or the second program register. We show that the optimal device, i.e., the one that maximizes the probability of success, is universal. It does not depend on the actual unknown states that we wish to discriminate.     

Noble gas mixture CW hollow cathode laser with internal anode system

A hollow cathode discharge tube with internal anodes was found to operate at significantly higher discharge voltages than a conventional HCD. A laser tube having internal anodes was constructed and laser operation was investigated in He-Kr, He-Ar and He-Ne-Xe gas mixtures. Due to the increased voltage low threshold currents and increased output power were obtained at the 4694 Å Kr ion and the 4765 Å Ar ion transitions. CW laser oscillation was observed for the first time at the 5314 Å and 4863 Å transitions of Xe II.     

Quantitative complementarity relations in bipartite systems: Entanglement as a physical reality

We introduce a complete set of complementary quantities in bipartite, two-dimensional systems. Complementarity then relates the quantitative entanglement measure concurrence which is a bipartite property to the single-particle quantum properties predictability and visibility, for the most general quantum state of two qubits. Consequently, from an interferometric point of view, the usual wave-particle duality relation must be extended to a “triality” relation containing, in addition, the quantitative entanglement measure concurrence, which has no classical counterpart and manifests a genuine quantum aspect of bipartite systems. A generalized duality relation, that also governs possible violations of the Bell’s inequality, arises between single- and bipartite properties.     

A Line-Search Algorithm Inspired by the Adaptive Cubic Regularization Framework and Complexity Analysis

Adaptive regularized framework using cubics has emerged as an alternative to line-search and trust-region algorithms for smooth nonconvex optimization, with an optimal complexity among second-order methods. In this paper, we propose and analyze the use of an iteration dependent scaled norm in the adaptive regularized framework using cubics. Within such a scaled norm, the obtained method behaves as a line-search algorithm along the quasi-Newton direction with a special backtracking strategy. Under appropriate assumptions, the new algorithm enjoys the same convergence and complexity properties as adaptive regularized algorithm using cubics. The complexity for finding an approximate first-order stationary point can be improved to be optimal whenever a second-order version of the proposed algorithm is regarded. In a similar way, using the same scaled norm to define the trust-region neighborhood, we show that the trust-region algorithm behaves as a line-search algorithm. The good potential of the obtained algorithms is shown on a set of large-scale optimization problems.