Entangled and disentangled evolution for a single atom in a driven cavity

For an atom in an externally driven cavity, we show that special initial states lead to near-disentangled atom-field evolution, and superpositions of these can lead to near maximally-entangled states. Somewhat counterintutively, we find that (moderate) spontaneous emission in this system actually leads to a transient increase in entanglement beyond the steady-state value. We also show that a particular field correlation function could be used, in an experimental setting, to track the time evolution of this entanglement

Modelling large motion events in fMRI studies of patients with epilepsy

EEG-correlated fMRI can provide localisation information on the generators of epileptiform discharges in patients with focal epilepsy. To increase the technique's clinical potential, it is important to consider ways of optimising the yield of each experiment while minimizing the risk of false-positive activation. Head motion can lead to severe image degradation and result in false-positive activation and is usually worse in patients than in healthy subjects. We performed general linear model fMRI data analysis on simultaneous EEG–fMRI data acquired in 34 cases with focal epilepsy. Signal changes associated with large inter-scan motion events (head jerks) were modelled using modified design matrices that include ‘scan nulling’ regressors. We evaluated the efficacy of this approach by mapping the proportion of the brain for which F-tests across the additional regressors were significant. In 95% of cases, there was a significant effect of motion in 50% of the brain or greater; for the scan nulling effect, the proportion was 36%; this effect was predominantly in the neocortex. We conclude that careful consideration of the motion-related effects in fMRI studies of patients with epilepsy is essential and that the proposed approach can be effective

The Use of Lethal Force by Canadian Police Officers: Assessing the Influence of Female Police Officers and Minority Threat Explanations on Police Shootings Across Large Cities

This study examines the applicability of several theoretically derived accounts used to explain the variations in police killings across 39 of Canada’s largest cities over a 15-year period. Pooled time-series negative binomial regression results are consistent with the ethnic threat hypothesis by indicating that lethal police action is associated with the size of the ethnic minority population in each city. Political accounts are supported as non-linear specifications suggest that once ethnic minorities reach a numerical majority in our sample of cities there is a decline in police killings. Findings also support expectations that greater female representation within policing will reduce the use of lethal force by changing the overall culture of the department. Theoretical implications of our findings are discussed

The Racial Politics of Due Process Protection: Does partisanship or racial composition influence state-level adoption of recorded interrogation policies?

Discoveries of wrongful convictions have increased substantially over the last several decades. During this period, practitioners and scholars have been advocating for the adoption of policies aimed at reducing the likelihood of convicting a person for a crime they did not commit. Implementing such policies are vitally important not only because they help ensure that the innocent do not receive unwarranted sanctions or that the guilty go unpunished but also because cases of wrongful conviction can erode public confidence in the criminal justice system and trust in the rule of law. To avoid such outcomes, many states have adopted policies through legislation that aim to reduce system errors. It remains unclear, however, why some states appear more willing to provide due process protections against wrongful convictions than others. Findings suggest that dimensions of racial politics may help explain the reluctance of some states to adopt protections against wrongful convictions. Specifically, interaction terms show that states with a Republican governor and a large African American population are the least likely to adopt policies aimed at protecting against wrongful convictions. We thus identify important differences in the political and social context between U.S. states that influence the adoption of criminal justice policies

Structural Determinants of Municipal Police Force Size in Large Cities across Canada: Assessing the applicability of ethnic threat theories in the Canadian context

Substantial theoretical and empirical attention has been directed at isolating the structural conditions that lead to shifts in the size of metropolitan police departments in the United States. These studies rely heavily on ethnic and racial threat explanations, which imply that larger police forces will be employed in jurisdictions with larger minority populations. It is entirely unclear, though, whether such accounts are applicable outside the United States. This study fills this void in the literature by assessing the extent to which ethnic threat hypotheses can explain variations in police strength using data on 40 large Canadian cities from 1996 to 2006. Results show that the size of the minority population significantly influences the size of metropolitan police departments

Legislative Responses to Wrongful Conviction: Do partisan principals and advocacy efforts influence state-level criminal justice policy?

The number of discovered wrongful criminal convictions (and resulting exonerations) has increased over the past decade. These cases erode public confidence in the criminal justice system and trust in the rule of law. Many states have adopted laws that aim to reduce system errors but no study has examined why some states appear more willing to provide due process protections against wrongful convictions than others. Findings from regression estimates suggest that states with a Republican controlled legislature or more Republican voters are less likely to pass these laws while the presence of advocacy organizations that are part of the \u27innocence movement\u27 make legislative change more likely. We thus identify important differences in the political and social context between U.S. states that influence the adoption of criminal justice policies

Structural Determinants of Municipal Police Force Size in Large Cities across Canada: Assessing the applicability of ethnic threat theories in the Canadian context

Substantial theoretical and empirical attention has been directed at isolating the structural conditions that lead to shifts in the size of metropolitan police departments in the United States. These studies rely heavily on ethnic and racial threat explanations, which imply that larger police forces will be employed in jurisdictions with larger minority populations. It is entirely unclear, though, whether such accounts are applicable outside the United States. This study fills this void in the literature by assessing the extent to which ethnic threat hypotheses can explain variations in police strength using data on 40 large Canadian cities from 1996 to 2006. Results show that the size of the minority population significantly influences the size of metropolitan police departments

Racial Residential Segregation and Social Control: A Panel Study of the Variation in Police Strength Across U.S Cities, 1980–2010

Despite a great deal of theoretical and empirical attention given to racial residential segregation and its influence on a number of social problems in the United States, few scholars have examined the role that this persistent form of racial inequality plays in shaping the magnitude of formal social control efforts. Our study examines this relationship by assessing the potential influence that the isolation of minorities may have on efforts to control crime in urban centers across the United States. Using a pooled time-series regression technique well suited for the analysis of aggregate, longitudinal data, we assess the potential influence of racial segregation on the size of municipal police departments in 170 U.S. cities between 1980 and 2010. After accounting for minority group size, economic threat, crime, and disorganization, we find that racial residential segregation has a significant non-linear effect on police force size. Cities with the most racially integrated populations have the smallest police presence but at very high levels of segregation, police strength levels off. This finding is consistent with expectations derived from the contact hypothesis. Under such conditions, majority group members appear to be less inclined to demand greater crime control measures such as increased police protection. Period interactions with residential segregation also suggest that this relationship has grown stronger in each decade since 1980. Overall, our study provides strong support for threat theories and the contact hypothesis but offers necessary refinements

Legislative Responses to Wrongful Conviction: Do partisan principals and advocacy efforts influence state-level criminal justice policy?

The number of discovered wrongful criminal convictions (and resulting exonerations) has increased over the past decade. These cases erode public confidence in the criminal justice system and trust in the rule of law. Many states have adopted laws that aim to reduce system errors but no study has examined why some states appear more willing to provide due process protections against wrongful convictions than others. Findings from regression estimates suggest that states with a Republican controlled legislature or more Republican voters are less likely to pass these laws while the presence of advocacy organizations that are part of the \u27innocence movement\u27 make legislative change more likely. We thus identify important differences in the political and social context between U.S. states that influence the adoption of criminal justice policies

Electron spin tomography through counting statistics: a quantum trajectory approach

We investigate the dynamics of electron spin qubits in quantum dots. Measurement of the qubit state is realized by a charge current through the dot. The dynamics is described in the framework of the quantum trajectory approach, widely used in quantum optics, and we show that it can be applied successfully to problems in condensed matter physics. The relevant master equation dynamics is unravelled to simulate stochastic tunneling events of the current through the dot.Quantum trajectories are then used to extract the counting statistics of the current. We show how, in combination with an electron spin resonance (ESR) field, counting statistics can be employed for quantum state tomography of the qubit state. Further, it is shown how decoherence and relaxation time scales can be estimated with the help of counting statistics, in the time domain. Finally, we discuss a setup for single shot measurement of the qubit state without the need for spin-polarized leads.Comment: 23 pages, 10 figures, RevTeX4, submitted to PR