Gregg Jaeger

Optimal distinction between two non-orthogonal quantum states

Abstract Two procedures are developed for classifying an individual system as | p > or | q >, non-orthogonal, given an ensemble with respective proportions r and 1— r . One (generalizing Ivanovic, Dieks, and Peres) infallibly classifies some systems, leaving others unclassified. The second is statistically optimum, allowing individual errors.

Entanglement, Information, and the Interpretation of Quantum Mechanics

This book explores the nature of quantum entanglement and quantum information and their role in the quantum world. Their relations to a number of key experiments and thought experiments in the history of quantum physics are considered, as is a range of interpretations of quantum mechanics that have been put forward as a means of understanding the fundamental nature of microphysics - the traditionally accepted domain of quantum mechanics - and in some cases, the universe as a whole. In this way, the book reveals the deep significance of entanglement and quantum information for our understanding of the physical world.

Calculating characteristics of noncollinear phase matching in uniaxial and biaxial crystals

A method of calculating the characteristics of noncollinear phase matching in both uniaxial and biaxial crystals is presented. Al- though significant work has been done to characterize collinear phase matching and to present many of its applications, noncollinear phase matching also has unique characteristics, leading to several useful ap- plications. The method presented enables calculations of both the collin- ear and noncollinear cases, and enables a far larger set of nonlinear crystals and configurations to be studied.

Philosophy of Quantum Information and Entanglement

Recent work in quantum information science has produced a revolution in our understanding of quantum entanglement. Scientists now view entanglement as a physical resource with many important applications. These range from quantum computers, which would be able to compute exponentially faster than classical computers, to quantum cryptographic techniques, which could provide unbreakable codes for the transfer of secret information over public channels. These important advances in the study of quantum entanglement and information touch on deep foundational issues in both physics and philosophy. This interdisciplinary volume brings together fourteen of the worlds leading physicists and philosophers of physics to address the most important developments and debates in this exciting area of research. It offers a broad spectrum of approaches to resolving deep foundational challenges - philosophical, mathematical, and physical - raised by quantum information, quantum processing, and entanglement. This book is ideal for historians, philosophers of science and physicists.

Entanglement sudden death in qubit–qutrit systems

We demonstrate the existence of entanglement sudden death (ESD), the complete loss of entanglement in finite time, in qubit-qutrit systems. In particular, ESD is shown to occur in such systems initially prepared in a one-parameter class of entangled mixed states and then subjected to local dephasing noise. Together with previous results, this proves the existence of ESD for some states in all quantum systems for which rigorously defined mixed-state entanglement measures have been identified. We conjecture that ESD exists in all quantum systems prepared in appropriate bipartite states.

Tests of a Two-Photon Technique for Measuring Polarization Mode Dispersion With Subfemtosecond Precision

An investigation is made of a recently introduced quantum interferometric method capable of measuring polarization mode dispersion (PMD) on sub-femtosecond scales, without the usual interferometric stability problems associated with such small time scales. The technique makes use of the extreme temporal correlation of orthogonally polarized pairs of photons produced via type-II phase-matched spontaneous parametric down-conversion. When sent into a simple polarization interferometer these photon pairs produce a sharp interference feature seen in the coincidence rate. The PMD of a given sample is determined from the shift of that interference feature as the sample is inserted into the system. The stability and resolution of this technique is shown to be below 0.2 fs. We explore how this precision is improved by reducing the length of the down-conversion crystal and increasing the spectral band pass of the system.

Local-dephasing-induced entanglement sudden death in two-component finite-dimensional systems

Entanglement sudden death (ESD), the complete loss of entanglement in finite time, is demonstrated to occur in a class of bipartite states of qu-d-it pairs of any finite dimension d > 2, when prepared in so-called ‘isotropic states’ and subject to multi-local dephasing noise alone. This extends previous results for qubit pairs [T. Yu, J. H. Eberly, Phys. Rev. Lett. 97, 140403 (2006)] to all qu-d-it pairs with d > 2.

Finite-Time Destruction of Entanglement and Non-Locality by Environmental Influences

Entanglement and non-locality are non-classical global characteristics of quantum states important to the foundations of quantum mechanics. Recent investigations have shown that environmental noise, even when it is entirely local in influence, can destroy both of these properties in finite time despite giving rise to full quantum state decoherence only in the infinite time limit. These investigations, which have been carried out in a range of theoretical and experimental situations, are reviewed here.

Entanglement, mixedness, and spin-flip symmetry in multiple-qubit systems

A relationship between a recently introduced multipartite entanglement measure, state mixedness, and spin-flip symmetry is established for any finite number of qubits. It is also shown that, for those classes of states invariant under the spin-flip transformation, there is a complementarity relation between multipartite entanglement and mixedness. A number of example classes of multiple-qubit systems are studied in light of this relationship.

Local basis-dependent noise-induced Bell-nonlocality sudden death in tripartite systems

We demonstrate that multipartite Bell-inequality violations can be fully destroyed in finite time in three-qubit systems subject only to the mechanism of local external asymptotic dephasing noise. This broadens the study of local-noise-induced sudden death of nonlocal behavior, extending it beyond the realm of bipartite systems, to which it had previously been restricted.