The quantum theory of antiferromagnetism in metals is necessary for our understanding of numerous intermetallic compounds of widespread interest. In these systems, a quantum critical point emerges as external parameters (such as chemical doping) are varied. Because of the strong coupling nature of this critical point and the "sign problem" plaguing numerical quantum Monte Carlo (QMC) methods, i...

Compact ultraviolet light sources are currently of high interest for a range of applications, including solid-state lighting, short-range communication, and bio-chemical detection. We report on the design and analysis of AlGaN-based lightemitting diodes with an emission wavelength near 280 nm. Internal device physics is investigated by threedimensional numerical simulation. The simulation incor...

The Dirac wave function is represented in a form where all its components have obvious geometrical and physical interpretations. Six components compose a Lorentz transformation determining the electron velocity are spin directions. This provides the basis for a rigorous connection between relativistic rigid body dynamics and the time evolution of the wave function. The scattering matrix is give...

Let H be a generalized N body Schrödinger operator with very short range potentials. Using Melrose’s scattering calculus, it is shown that the free channel ‘geometric’ scattering matrix, defined via asymptotic expansions of generalized eigenfunctions of H, coincides (up to normalization) with the free channel ‘analytic’ scattering matrix defined via wave operators. Along the way, it is shown th...

Quantum field theory (QFT) presents a genuine example of the underdetermination of theory by empirical evidence. There are variants of QFT which are empirically indistinguishable yet support different interpretations. This case is of particular interest to philosophers of physics because, before the philosophical work of interpreting QFT can proceed, the question of which variant should be subj...

We construct a set of order parameters for non-Abelian gauge theories which probe directly the unbroken group and are free of the deficiencies caused by quantum fluctuations and gauge fixing which have plagued all previous attempts. These operators can be used to map out the phase diagram of a non-Abelian gauge theory. PACS numbers:11.15.-q,03.65.Bz,03.80.+r Typeset using REVTEX

The difficulty of simulating quantum systems, well known to quantum chemists, prompted the idea of quantum computation. One can avoid the steep scaling associated with the exact simulation of increasingly large quantum systems on conventional computers, by mapping the quantum system to another, more controllable one. In this review, we discuss to what extent the ideas in quantum computation, no...

A fundamental problem in quantum theory is to establish a connection between its local description (quantum field theory) and measurable quantities (particle masses, scattering amplitudes). In elementary particle physics one relies mostly on approximation techniques due to the non-integrable structure of the interactions. In order to gain a deeper understanding of quantum theory in general thes...