Enhancement and state tomography of a squeezed vacuum with circuit quantum electrodynamics

We study the dynamics of a general quartic interaction Hamiltonian under the influence of dissipation and non-classical driving. We show that this scenario could be realised with a cascaded superconducting cavity-qubit system in the strong dispersive regime in a setup similar to recent experiments. In the presence of dissipation, we find that an effective Hartree-type decoupling with a Fokker-Planck equation yields a good approximation. We find that the stationary state is approximately a squeezed vacuum, which is enhanced by the $Q$-factor of the cavity but conserved by the interaction. The qubit non-linearity, therefore, does not significantly influence the highly squeezed intracavity microwave field but, for a range of realistic parameters, enables characterisation of itinerant squeezed fields

Designing Kerr interactions using multiple superconducting qubit types in a single circuit

The engineering of Kerr interactions has great potential for quantum information processing applications in multipartite quantum systems and for investigation of many-body physics in a complex cavity-qubit network. We study how coupling multiple different types of superconducting qubits to the same cavity modes can be used to modify the self- and cross-Kerr effects acting on the cavities and demonstrate that this type of architecture could be of significant benefit for quantum technologies. Using both analytical perturbation theory results and numerical simulations, we first show that coupling two superconducting qubits with opposite anharmonicities to a single cavity enables the effective self-Kerr interaction to be diminished, while retaining the number splitting effect that enables control and measurement of the cavity field. We demonstrate that this reduction of the self-Kerr effect can maintain the fidelity of coherent states and generalised Schr\"{o}dinger cat states for much longer than typical coherence times in realistic devices. Next, we find that the cross-Kerr interaction between two cavities can be modified by coupling them both to the same pair of qubit devices. When one of the qubits is tunable in frequency, the strength of entangling interactions between the cavities can be varied on demand, forming the basis for logic operations on the two modes. Finally, we discuss the feasibility of producing an array of cavities and qubits where intermediary and on-site qubits can tune the strength of self- and cross-Kerr interactions across the whole system. This architecture could provide a way to engineer interesting many-body Hamiltonians and a useful platform for quantum simulation in circuit quantum electrodynamics

Inefficiencies in Networked Markets

In many markets, relationship specific investments are necessary for trade. These formed relationships constitute a networked market in which not all buyers can trade with all sellers. We show that networked markets can be decomposed to identify how alternative trading opportunities affect who trades with whom and at what price. This uncovers agents' incentives to invest in relationships. Investment inefficiencies can eliminate all the gains from trade, but for reasons that differ depending on how investments are made. Three applications are considered in detail: high-skill labor markets, merger markets when industries are consolidating, and the international market for natural gas. (JEL C78, D85, D86) </jats:p

Firm Heterogeneity and Export Participation: A New Asian Tiger Perspective

This paper investigates the relationship between firm heterogeneity and a firm’s decision to export, using the annual survey of Thai manufacturing firms from 2001 to 2004. A significant contribution of this paper is that we are, for the first time, able to break down FDI by country of origin to observe whether the behavior of MNEs differs by region of origin. We find that entry sunk costs and firm characteristics are important factors in explaining a firm’s decision to export. Another important determinant is the ownership structure of the firm, with foreign owned firms having a higher probability of exporting than domestically owned firms although this differs across country of ownership with potentially important policy implications. Export platform FDI is used to explain the behavior of foreign firms that invest in Thailand. Using three measures of total factor productivity, we also find that highly productive firms self-select into the export market. The implication for governments of developing countries is the need to think carefully about how and to whom they target their inward FDI policies as a means of growth. The heterogeneous behavior of multinationals from different nations means that policies targeting specific regions or countries may be preferable to general tax concessions or the implementation of special economic zones that are open to all.FDI, exports, firm heterogeneity, development

Happy Inconsistency: Health Claims Standards at the FTC and FDA

We live in a society increasingly preoccupied with healthy food. Restaurant menus now include "heart smart" options, network news programs run segments on teenage vegetarians, consumer groups denounce our beloved movie popcorn, and people dead set against the metric system count fat grams in their light beers. At the same time, of course, the percentage of obese people in our country has reached bulging proportions. In the face of all this, enterprising manufacturers see a way to improve the general welfare--and make a decent profit--by providing healthier foods. Educating the consumer about the benefits of a better diet is necessary to open up new market niches. Health sells, and manufacturers have been understandably eager to seize the day

The Perception of the Value of the Use of Primary Source Documents among East Tennessee Lakeway Area History Teachers in Grades 5-12.

This study examines the perceptions of history and social studies teachers in the Lakeway Area of East Tennessee concerning the use of primary source materials in classroom instruction. The purpose of this study was to determine what value the educators in the intact group held for the use of primary source documents, how much time was devoted to the analysis of primary source documents by students in those classes, and potential barriers to the implementation of the use of primary source materials. The research design was descriptive and used data gathered from a survey instrument constructed by the researcher. A pilot test of the instrument was conducted, reliability coefficients were calculated, and the survey instrument was modified. The final survey consisted of 44 statements, a demographic section, and four open-response questions. A total of two hundred eighteen surveys were sent to eligible educators in Cocke, Grainger, Hamblen, Hawkins,and Jefferson counties. One hundred fourteen of the surveys were returned and were used for this study. Other variables studied were gender, job classification, years of experience, the amount of time reported using primary sources in class, past or current membership in the National Council for Social Studies, participation in professional development emphasizing primary source analysis, and the type of teaching certification held by the respondents. The findings include: The two greatest obstacles to the implementation of the use of primary source materials were lack of training or relevant experience and the perceived access to materials; comfort in using technology and ability level of students did not appear to be significant obstacle barriers; all categories of respondents held a positive opinion of the use of primary sources. A review of the responses to the open-response questions revealed that time could also have been an obstacle barrier to the implementation of the use of primary sources. It appears that the lack of training or relevant experience, the perceived access to materials, and perhaps time may be limiting factors in determining the amount of time educators in this area devote the primary source analysis