Understanding Of Quantum Physics Research Articles

Quantum Information

AbstractThe following article is based on the plenary address by Luiz Davidovich (Federal University of Rio de Janeiro), presented on April 14, 2004, at the 2004 MRS Spring Meeting in San Francisco. The field of quantum information is a discipline that aims to investigate methods for characterizing, transmitting, storing, compressing, and computationally utilizing the information carried by quantum states. It owes its rapid development over the last few years to several factors: the ability, developed in several laboratories, to control and measure simple microscopic systems; the discovery of fast quantum algorithms; and the recognition that Moore's law will soon lead to the single-atom limit of elementary computing gates.Cryptography and quantum computing are among the main applications in the field.They rely on the subtle and fundamental properties of the quantum world: the unavoidable disturbance associated with measurement, the superposition principle, and the nonlocal properties of entangled states. Progress in this area is intimately connected to a deep understanding of quantum physics: recent achievements include the experimental demonstration of teleportation and detailed investigations of the role of the environment in the quantum–classical transition. This article reviews basic concepts and recent developments in the field of quantum information, emphasizing the close ties between fundamental research and possible applications.

Insights into students' understanding of quantum physics: visualizing quantum entities

Ninety years after the genesis of quantum physics significant research on students' understanding of such revolutionary phenomena is beginning to emerge. What are photons really like? Are they like particles or waves? Are they like both particles and waves, or like neither? The implications of quantum theory for the commonsense notion of an object illustrate the difficulties in using ordinary experience to make sense of the subatomic world. Part of the findings of a series of studies investigating students' understanding of quantum physics is presented, describing students' visualizations of quantum entities (i.e. electrons and photons).

Jumps in quantum theory

In this paper we review the discussion about quantum jumps. We sketch the historical background before we present the recent revival of this problem originating in the field of atomic investigations. We present both the theoretical methods and their motivations, the relevance to experiments and an attempt at a preliminary discussion of the role of these developments in our fundamental understanding of quantum physics.

Two approaches for the conformal degree of freedom

The conformal degree of freedom in the gravitational force is a significant object worth studying for the sake of the deeper understanding of quantum physics. After defining the procedure of euclideanization explicitly, we investigate two independent approaches for constructing a well-defined Euclidean path integral formulation, paying special attention to the treatment for the conformal mode. In the first approach, we adopt the policy that the Lorentzian framework is fundamental and that the Euclidean scheme should be formulated so that the latter adjusts to the former. In the second approach, we try to unify both frameworks, leading to a novel path integral formula. It is hoped that both approaches, besides the conformal-rotation technique, serve the Euclidean quantum mechanics and quantum cosmology.

FINDING A SINGLE MOLECULE IN A HAYSTACK

Optical detection and spectroscopy of single tons in vacuum confined in electromagnetic traps1 have led to novel measurements that test our understanding of quantum physics. The detection and spectroscopy of a single absorber in a solid [single molecule detection (SMD)] would provide a useful tool for the study of local host- absorber interactions where the absorbing center is at rest, confined by the host lattice, and where the normal averaging over many equivalent centers is removed.

Why the classical–quantal dualism is still with us

Through a series of short steps we try to make clear why the classical–quantal dualism is still indispensable, despite the advances in our understanding of quantum physics.