Racing Multi-Objective Selection Probabilities

In the context of Noisy Multi-Objective Optimization, dealing with uncertainties requires the decision maker to define some preferences about how to handle them, through some statistics (e.g., mean, median) to be used to evaluate the qualities of the solutions, and define the corresponding Pareto set. Approximating these statistics requires repeated samplings of the population, drastically increasing the overall computational cost. To tackle this issue, this paper proposes to directly estimate the probability of each individual to be selected, using some Hoeffding races to dynamically assign the estimation budget during the selection step. The proposed racing approach is validated against static budget approaches with NSGA-II on noisy versions of the ZDT benchmark functions

Photonic circuits for generating modal, spectral, and polarization entanglement

We consider the design of photonic circuits that make use of Ti:LiNbO$_{3}$ diffused channel waveguides for generating photons with various combinations of modal, spectral, and polarization entanglement. Down-converted photon pairs are generated via spontaneous optical parametric down-conversion (SPDC) in a two-mode waveguide. We study a class of photonic circuits comprising: 1) a nonlinear periodically poled two-mode waveguide structure, 2) a set of single-mode and two-mode waveguide-based couplers arranged in such a way that they suitably separate the three photons comprising the SPDC process, and, for some applications, 3) a holographic Bragg grating that acts as a dichroic reflector. The first circuit produces frequency-degenerate down-converted photons, each with even spatial parity, in two separate single-mode waveguides. Changing the parameters of the elements allows this same circuit to produce two nondegenerate down-converted photons that are entangled in frequency or simultaneously entangled in frequency and polarization. The second photonic circuit is designed to produce modal entanglement by distinguishing the photons on the basis of their frequencies. A modified version of this circuit can be used to generate photons that are doubly entangled in mode number and polarization. The third photonic circuit is designed to manage dispersion by converting modal, spectral, and polarization entanglement into path entanglement

Selection in Zea mays L. by inbred line appearance and testcross performance in low and high plant densities

The development of inbred lines and the search for their best hybrid combinations are the main bases of corn improvement in the United States. The most commonly used method for inbred development is to enforce self fertilization for several generations while practicing visual selection for the more highly heritable characteristics. During these generations, surviving stocks maintained on an ear-to-row basis become highly homozygous and highly homogeneous. Because\u27 evaluation for combining ability by using test-cross procedures is expensive, it is usually delayed until after three to five generations of visual selection. Visual selection for combining ability among inbred progenies is rarely emphasized because of the commonly held opinion that it is relatively ineffective. Regardless of the effectiveness of visual selection, total genetic variability will be reduced following each selection cycle, according to the principle that the variability of a sample is less than the variability of a population. If selection is effective, the reduction will be even greater because of the removal of undesired genes, but the mean of the selected lines will exceed the mean of the original population. Early testing, as proposed by Jenkins ( 1935 ), takes advantage of evaluation for combining ability in the So generation of a maize population, or the F2 of a hybrid, before genes have been eliminated by selection and, therefore, when the genetic variability among individuals is at a maximum. Superior germ plasm, identified by early testing, need not face the hazard of several generations of random sampling as in visual selection. However, the considerable expense of testing restricts the size and, therefore, the genetic base of the original population

Generating Polarization-Entangled Photon Pairs with Arbitrary Joint Spectrum

We present a scheme for generating polarization-entangled photons pairs with arbitrary joint spectrum. Specifically, we describe a technique for spontaneous parametric down-conversion in which both the center frequencies and the bandwidths of the down-converted photons may be controlled by appropriate manipulation of the pump pulse. The spectral control offered by this technique permits one to choose the operating wavelengths for each photon of a pair based on optimizations of other system parameters (loss in optical fiber, photon counter performance, etc.). The combination of spectral control, polarization control, and lack of group-velocity matching conditions makes this technique particularly well-suited for a distributed quantum information processing architecture in which integrated optical circuits are connected by spans of optical fiber.Comment: 6 pages, 3 figure

Performance of Photon-Pair Quantum Key Distribution Systems

We analyze the quantitative improvement in performance provided by a novel quantum key distribution (QKD) system that employs a correlated photon source (CPS) and a photon-number resolving detector (PNR). Our calculations suggest that given current technology, the CPR implementation offers an improvement of several orders of magnitude in secure bit rate over previously described implementations

Fundamental Limits of Classical and Quantum Imaging

Quantum imaging promises increased imaging performance over classical protocols. However, there are a number of aspects of quantum imaging that are not well understood. In particular, it has so far been unknown how to compare classical and quantum imaging procedures. Here, we consider classical and quantum imaging in a single theoretical framework and present general fundamental limits on the resolution and the deposition rate for classical and quantum imaging. The resolution can be estimated from the image itself. We present a utility function that allows us to compare imaging protocols in a wide range of applications.Comment: 4 pages, 3 figures; accepted for Physical Review Letters, with updated title and fixed typo