Mechanisms for Lasing with Cold Atoms as the Gain Medium

We realize a laser with a cloud of cold rubidium atoms as gain medium, placed in a low-finesse cavity. Three different regimes of laser emission are observed corresponding respectively to Mollow, Raman and Four Wave Mixing mechanisms. We measure an output power of up to 300 $\mu$W and present the main properties of these different lasers in each regime

A quantum algorithm providing exponential speed increase for finding eigenvalues and eigenvectors

We describe a new polynomial time quantum algorithm that uses the quantum fast fourier transform to find eigenvalues and eigenvectors of a Hamiltonian operator, and that can be applied in cases (commonly found in ab initio physics and chemistry problems) for which all known classical algorithms require exponential time. Applications of the algorithm to specific problems are considered, and we find that classically intractable and interesting problems from atomic physics may be solved with between 50 and 100 quantum bits.Comment: 10 page

Poisoning the Next Apple? The America Invents Act and Individual Inventors

The Leahy-Smith America Invents Act, the most significant patent law reform effort in two generations, has a dark side: It seems likely to decrease the patenting behavior of small inventors, a category which occupies special significance in American innovation history. In this paper we empirically predict the effects of the major change in the law: a shift in the patent priority rules from the United States’ traditional “first-to-invent” system to the predominant “first-to-file” system. While there has been some theoretical work on this topic, we use the Canadian experience with a similar change as a natural experiment to shed the first empirical light on the question. Our analysis uses a difference-in-difference framework to estimate the impact of the Canadian law change on small inventors. Using data on all patents granted by the Canadian Intellectual Property Office and the US Patent and Trademark Office, we find a significant drop in the fraction of patents granted to small inventors in Canada coincident with the implementation of first-to-file. We also find no measurable changes in patent quality and perform several additional analyses to rule out alternative explanations. While the net welfare impact that can be expected from a shift to first-to-file is unclear, our results do reveal that, contrary to the conventional wisdom, the March 2013 implementation of a first-to-file rule in the U.S. is likely to result in reduced patenting behavior by individual inventors

Poisoning the Next Apple? The America Invents Act and Individual Inventors

The Leahy-Smith America Invents Act, the most significant patent law reform effort in two generations, has a dark side: It seems likely to decrease the patenting behavior of small inventors, a category which occupies special significance in American innovation history. In this paper we empirically predict the effects of the major change in the law: a shift in the patent priority rules from the United States’ traditional “first-to-invent” system to the predominant “first-to-file” system. While there has been some theoretical work on this topic, we use the Canadian experience with a similar change as a natural experiment to shed the first empirical light on the question. Our analysis uses a difference-in-difference framework to estimate the impact of the Canadian law change on small inventors. Using data on all patents granted by the Canadian Intellectual Property Office and the US Patent and Trademark Office, we find a significant drop in the fraction of patents granted to small inventors in Canada coincident with the implementation of first-to-file. We also find no measurable changes in patent quality and perform several additional analyses to rule out alternative explanations. While the net welfare impact that can be expected from a shift to first-to-file is unclear, our results do reveal that, contrary to the conventional wisdom, the March 2013 implementation of a first-to-file rule in the U.S. is likely to result in reduced patenting behavior by individual inventors

Towards an understanding of GPs' viewpoint on diagnosing postnatal depression in general practice: a small-scale realist evaluation

BACKGROUND: Less than half of postnatal depression cases are identified in routine clinical assessment. Guidelines and current literature suggest that general practitioners (GPs) may have an opportunistic role in detecting postnatal depression due to their early contact and existing rapport with many new mothers. There is limited research on the diagnostic approaches chosen by GPs in different GP-patient contexts. Our small-scale study evaluates the thought processes of seven GPs based in one practice when forming a clinical diagnosis of postnatal depression under different contexts. METHODS: Seven GP participants were interviewed using case vignettes about postnatal depression, based on an adapted Johari's window framework. A realist approach to analysis was undertaken with the intention of understanding GPs' responses to different situations. Context-mechanism-outcome configurations were constructed, and a programme theory was formed to consolidate the findings. FINDINGS: Findings suggest that diagnoses may be a clinician-led or collaborative process between GP and patient. In collaborative contexts, stigmatising views were addressed by GPs, time for self-reflection was encouraged and mothers' views were accounted for. Clinician-led diagnoses often occurred in contexts where there was a lack of acknowledgement of symptoms on behalf of the patient or where safety was a concern. The personal and clinical experience of GPs themselves, as well as effective communication channels with other primary care professionals, was significant mechanisms. CONCLUSION: GPs use a variety of strategies to support patient disclosure and acceptance of their condition. The complexity of GP-patient contexts may influence the clinical thought process. We address some of the gaps in existing literature by exploring postnatal depression diagnosis in primary care and provide tentative explanations to suggest what works, for whom and in what contexts

Higher Order Methods for Simulations on Quantum Computers

To efficiently implement many-qubit gates for use in quantum simulations on quantum computers we develop and present methods reexpressing exp[-i (H_1 + H_2 + ...) \Delta t] as a product of factors exp[-i H_1 \Delta t], exp[-i H_2 \Delta t], ... which is accurate to 3rd or 4th order in \Delta t. The methods we derive are an extended form of symplectic method and can also be used for the integration of classical Hamiltonians on classical computers. We derive both integral and irrational methods, and find the most efficient methods in both cases.Comment: 21 pages, Latex, one figur

Nonlinear quantum mechanics implies polynomial-time solution for NP-complete and #P problems

If quantum states exhibit small nonlinearities during time evolution, then quantum computers can be used to solve NP-complete problems in polynomial time. We provide algorithms that solve NP-complete and #P oracle problems by exploiting nonlinear quantum logic gates. It is argued that virtually any deterministic nonlinear quantum theory will include such gates, and the method is explicitly demonstrated using the Weinberg model of nonlinear quantum mechanics.Comment: 10 pages, no figures, submitted to Phys. Rev. Let

Individual Accountability for Human Rights Abuses: Historical and Legal Underpinnings

The international legal community is beset today with talk of accountability. Governments, international organizations, non-governmental organizations, and scholars speak of the need to hold individuals responsible for official acts that violate the most cherished of international human rights. Some study the nature of various infractions with an eye toward codification; others seek to create or engage mechanisms for trying or otherwise punishing individuals. Their common mission is based on a shared understanding that international law has a role to play not only in setting standards for governments, non-state actors, and their agents, but in prescribing the consequences of a failure to meet those standards. To understand the promises and limitations of individual accountability as a means to protect human dignity requires treating it as a discrete subject of international law. As such, it demands appraisal of a complex amalgam of law and a wide spectrum of sanctioning processes that transcend orthodox divisions of subjects within international law. Its theory, doctrine, and practice spring from legal sources and events both ancient and modern; and ultimately an appreciation of the topic turns considerably on insights beyond international law, whether political or philosophical in origin. Before any examination of the substantive law and mechanisms can proceed, we begin with the evolution of this concept and the legal threads involved