The Red Dawn of Geoengineering: First Step Toward an Effective Governance for Stratospheric Injections

A landmark report by the National Academy of Sciences (NAS) issued in 2015 is the latest in a series of scientific studies to assess the feasibility of geoengineering with stratospheric aerosols to offset anthropogenic global warming and to conclude that they offer a possibly viable supplement or back-up alternative to reducing carbon dioxide emissions. The known past effect of major explosive volcanic eruptions temporarily moderating average worldwide temperatures provides evidence in support of this once taboo form of climate intervention. In the most extensive study to date, an elite NAS committee now suggests that such processes for adjusting global temperature, while still uncertain, merit further research and field testing. Every study stresses the need for transparent international governance of stratospheric injections, especially given that the benefits of such interventions are certain to be unevenly distributed and the risks are not fully known. After examining the roadblocks to such governance, this paper explores the statutory and common law frameworks that could provide some stop-gap approaches until the needed regulatory regime emerges

The Red Dawn of Geoengineering: First Step Toward an Effective Governance for Stratospheric Injections

A landmark report by the National Academy of Sciences (NAS) issued in 2015 is the latest in a series of scientific studies to assess the feasibility of geoengineering with stratospheric aerosols to offset anthropogenic global warming and to conclude that they offer a possibly viable supplement or back-up alternative to reducing carbon dioxide emissions. The known past effect of major explosive volcanic eruptions temporarily moderating average worldwide temperatures provides evidence in support of this once taboo form of climate intervention. In the most extensive study to date, an elite NAS committee now suggests that such processes for adjusting global temperature, while still uncertain, merit further research and field testing. Every study stresses the need for transparent international governance of stratospheric injections, especially given that the benefits of such interventions are certain to be unevenly distributed and the risks are not fully known. After examining the roadblocks to such governance, this paper explores the statutory and common law frameworks that could provide some stop-gap approaches until the needed regulatory regime emerges

Cavity state preparation using adiabatic transfer

We show how to prepare a variety of cavity field states for multiple cavities. The state preparation technique used is related to the method of stimulated adiabatic Raman passage or STIRAP. The cavity modes are coupled by atoms, making it possible to transfer an arbitrary cavity field state from one cavity to another, and also to prepare non-trivial cavity field states. In particular, we show how to prepare entangled states of two or more cavities, such as an EPR state and a W state, as well as various entangled superpositions of coherent states in different cavities, including Schrodinger cat states. The theoretical considerations are supported by numerical simulations.Comment: 11 pages, 9 figures. Accepted in Phys. Rev.

Cavity field ensembles from nonselective measurements

We continue our investigations of cavity QED with time dependent parameters. In this paper we discuss the situation where the state of the atoms leaving the cavity is reduced but the outcome is not recorded. In this case our knowledge is limited to an ensemble description of the results only. By applying the Demkov-Kunike level-crossing model, we show that even in this case, the filtering action of the interaction allows us to prepare a preassigned Fock state with good accuracy. The possibilities and limitations of the method are discussed and some relations to earlier work are presented.Comment: 11 pages, 2 figure

Travelling to exotic places with cavity QED systems

Recent theoretical schemes for utilizing cavity QED models as quantum simulators are reviewed. By considering a quadrature representation for the fields, it is shown how Jahn-Teller models, effective Abelian or non-Abelian gauge potentials, transverse Hall currents, and relativistic effects naturally arise in these systems. Some of the analytical predictions are verified numerically using realistic experimental parameters taking into account for system losses. Thereby demonstrating their feasibility with current experimental setups.Comment: 5 pages, 3 figure

Photon filters in a microwave cavity

In an earlier paper we have concluded that time-dependent parameters in atom-mode interaction can be utilized to modify the quantum field in a cavity. When an atom shoots through the cavity field, it is expected to experience a trigonometric time dependence of its coupling constant. We investigate the possibilities this offers to modify the field. As a point of comparison we use the solvable Rosen-Zener model, which has parameter dependencies roughly similar to the ones expected in a real cavity. We do confirm that by repeatedly sending atoms through the cavity, we can obtain filters on the photon states. Highly non-classical states can be obtained. We find that the Rosen-Zener model is more sensitive to the detuning than the case of a trigonometric coupling.Comment: 9 pages, 5 figure

Validity of adiabaticity in Cavity QED

This paper deals with the concept of adiabaticity for fully quantum mechanically cavity QED models. The physically interesting cases of Gaussian and standing wave shapes of the cavity mode are considered. An analytical approximate measure for adiabaticity is given and compared with numerical wave packet simulations. Good agreement is obtained where the approximations are expected to be valid. Usually for cavity QED systems, the large atom-field detuning case is considered as the adiabatic limit. We, however, show that adiabaticity is also valid, for the Gaussian mode shape, in the opposite limit. Effective semiclassical time dependent models, which do not take into account the shape of the wave packet, are derived. Corrections to such an effective theory, which are purely quantum mechanical, are discussed. It is shown that many of the results presented can be applied to time dependent two-level systems.Comment: 10 pages, 9 figure

Dynamics of a Raman coupled model: entanglement and quantum computation

The evolution of a Raman coupled three-level lambda atom with two quantized cavity modes is studied in the large detuning case; i.e. when the upper atomic level can be adiabatically eliminated. Particularly the situation when the two modes are prepared in initial coherent or squeezed states, with a large average number of photons, is investigated. It is found that the atom, after specific interaction times, disentangles from the two modes, leaving them, in certain cases, in entangled Schrodinger cat states. These disentanglement times can be controlled by adjusting the ratio between average numbers of photons in the two modes. It is also shown how this effective model may be used for implementing quantum information processing. Especially it is demonstrated how to generate various entangled states, such as EPR- and GHZ-states, and quantum logic operations, such as the control-not and the phase-gate.Comment: 8 pages, 6 figure

Science Icebreaker Activities: An Example from Gravitational Wave Astronomy

At the beginning of a class or meeting an icebreaker activity is often used to help loosen the group and get everyone talking. Our motivation is to develop activities that serve the purpose of an icebreaker, but are designed to enhance and supplement a science-oriented agenda. The subject of this article is an icebreaker activity related to gravitational wave astronomy. We first describe the unique gravitational wave signals from three distinct sources: monochromatic binaries, merging compact objects, and extreme mass ratio encounters. These signals form the basis of the activity where participants work to match an ideal gravitational wave signal with noisy detector output for each type of source.Comment: Accepted to The Physics Teacher. Original manuscript divided into two papers at the request of the referee. For a related paper on gravitational wave observatories see physics/050920