Pulse-mode quantum projection synthesis: Effects of mode mismatch on optical state truncation and preparation

Quantum projection synthesis can be used for phase-probability-distribution measurement, optical-state truncation and preparation. The method relies on interfering optical lights, which is a major challenge in experiments performed by pulsed light sources. In the pulsed regime, the time frequency overlap of the interfering lights plays a crucial role on the efficiency of the method when they have different mode structures. In this paper, the pulsed mode projection synthesis is developed, the mode structure of interfering lights are characterized and the effect of this overlap (or mode match) on the fidelity of optical-state truncation and preparation is investigated. By introducing the positive-operator-valued measure (POVM) for the detection events in the scheme, the effect of mode mismatch between the photon-counting detectors and the incident lights are also presented.Comment: 11 pages, 4 figures, submitted to Phys. Rev.

Dimensionless cosmology

Although it is well known that any consideration of the variations of fundamental constants should be restricted to their dimensionless combinations, the literature on variations of the gravitational constant $G$ is entirely dimensionful. To illustrate applications of this to cosmology, we explicitly give a dimensionless version of the parameters of the standard cosmological model, and describe the physics of Big Bang Neucleosynthesis and recombination in a dimensionless manner. The issue that appears to have been missed in many studies is that in cosmology the strength of gravity is bound up in the cosmological equations, and the epoch at which we live is a crucial part of the model. We argue that it is useful to consider the hypothetical situation of communicating with another civilization (with entirely different units), comparing only dimensionless constants, in order to decide if we live in a Universe governed by precisely the same physical laws. In this thought experiment, we would also have to compare epochs, which can be defined by giving the value of any {\it one} of the evolving cosmological parameters. By setting things up carefully in this way one can avoid inconsistent results when considering variable constants, caused by effectively fixing more than one parameter today. We show examples of this effect by considering microwave background anisotropies, being careful to maintain dimensionlessness throughout. We present Fisher matrix calculations to estimate how well the fine structure constants for electromagnetism and gravity can be determined with future microwave background experiments. We highlight how one can be misled by simply adding $G$ to the usual cosmological parameter set

A Preliminary ecotoxicological assessment of Asian carp species in the Mississippi and Illinois Rivers

Project Completion Report issued March 2005Report issued on: March 2005INHS Technical Report prepared for Illinois - Indiana Sea Gran

Laser photodetachment mass spectrometry

We demonstrate that the technique of laser photodetachment spectroscopy on atomic negative ions can be used as a sensitivity enhancement tool in mass spectrometry, useful for suppressing both isotopic as well as molecular isobaric interferences. In the experiment a beam of negative ions and a laser beam are merged in a collinear geometry and the wavelength of the laser is tuned across the photodetachment threshold region. Due to the large differential Doppler shifts associated with the fast moving ions of different masses, it is possible to selectively detach ions of certain isotopes while leaving others unaffected. By choosing co-propagating laser and ion beams, the heavier isotopes of an element can be selectively detached, whereas counter propagating beams can be used to detach the lighter ones. In this paper we demonstrate the feasibility of the method in an experiment that was designed to selectively detach either 32S− or 34S− ions. The isotopic ratio of 34S/32S was enhanced by a factor of >50 over the natural value. This factor can be improved by using a laser that is better adapted to the measurement and by improving the vacuum conditions in order to further suppress the collisional background. The applicability of this technique to selectivity enhancement in measurements of the abundances of rare or ultra-rare isotopes is discussed

RADIATIVE LIFETIMES OF HIGHLY IONIZED AND FOIL-EXCITED Al.

Des spectres d'atomes d'aluminium très ionisés par une cible de carbone ont été enregistrés dans le domaine spectral de 300 à 1000 Å, à 10, 20, 30 et 45 MeV d'énergie de faisceau, en utilisant l'accélérateur tandem d'Uppsala. Les durées de vie de quelques niveaux bas de l'aluminium à 3-, 4-, 5- électrons ont été mesurées avec la méthode faisceaucible. Les forces d'oscillateurs ont été calculées et comparées avec les valeurs théoriques.Foil-excited spectra of multiply charged Al ions in the spectral range ~300-1000 Å have been recorded at 10, 20, 30 and 45 MeV beam energies using the Uppsala tandem accelerator. Radiative lifetimes of some of the low-lying levels in 3-, 4- and 5-electron Al were measured using the beam-foil time of flight method. Oscillator strengths have been derived from the measurements and will be compared with theory