Super-resolving multi-photon interferences with independent light sources

We propose to use multi-photon interferences from statistically independent light sources in combination with linear optical detection techniques to enhance the resolution in imaging. Experimental results with up to five independent thermal light sources confirm this approach to improve the spatial resolution. Since no involved quantum state preparation or detection is required the experiment can be considered an extension of the Hanbury Brown and Twiss experiment for spatial intensity correlations of order N>2

Adaptive strategies for graph state growth in the presence of monitored errors

Graph states (or cluster states) are the entanglement resource that enables one-way quantum computing. They can be grown by projective measurements on the component qubits. Such measurements typically carry a significant failure probability. Moreover, they may generate imperfect entanglement. Here we describe strategies to adapt growth operations in order to cancel incurred errors. Nascent states that initially deviate from the ideal graph states evolve toward the desired high fidelity resource without impractical overheads. Our analysis extends the diagrammatic language of graph states to include characteristics such as tilted vertices, weighted edges, and partial fusion, which arise from experimental imperfections. The strategies we present are relevant to parity projection schemes such as optical `path erasure' with distributed matter qubits.Comment: 4 pages, 4 figures. Typos corrected, nicer figures, neater notation and better rea

New relational understandings of city building:Reading the city through dynamic landscapes of spatial governance

In this think piece I will take you on a journey to share my approach to reading contemporary city building, which is increasingly chaotic, fragmented, and complex. Spatial governance, in my understanding, refers to the collective efforts to coordinate and structure the dynamic institutional activities of a variety of actors that aim to organise the built environment. Urban planning is one of these efforts, though not the only one. Therefore, in this article, I will visualise spatial governance as a dynamic landscape which accommodates multi-actor, multi-scalar, multi-loci and multi-temporal regulatory activities related to the uncertainties, opportunities, and crises of the market. Reading dynamic landscapes of spatial governance requires an understanding of regulatory efforts as they refer to the relational behaviour of state, market, and community actors. This approach, to linking regulatory efforts to relational behaviour, in my view, gives us new opportunities to provide comprehensive understandings of how cities develop under market-driven conditions

Global and regional importance of the direct dust-climate feedback.

Feedbacks between the global dust cycle and the climate system might have amplified past climate changes. Yet, it remains unclear what role the dust-climate feedback will play in future anthropogenic climate change. Here, we estimate the direct dust-climate feedback, arising from changes in the dust direct radiative effect (DRE), using a simple theoretical framework that combines constraints on the dust DRE with a series of climate model results. We find that the direct dust-climate feedback is likely in the range of -0.04 to +0.02 Wm -2 K-1, such that it could account for a substantial fraction of the total aerosol feedbacks in the climate system. On a regional scale, the direct dust-climate feedback is enhanced by approximately an order of magnitude close to major source regions. This suggests that it could play an important role in shaping the future climates of Northern Africa, the Sahel, the Mediterranean region, the Middle East, and Central Asia

Transmission of pillar-based photonic crystal waveguides in InP technology

Waveguides based on line defects in pillar photonic crystals have been fabricated in InP/InGaAsP/InP technology. Transmission measurements of different line defects are reported. The results can be explained by comparison with two-dimensional band diagram simulations. The losses increase substantially at mode crossings and in the slow light regime. The agreement with the band diagrams implies a good control on the dimensions of the fabricated features, which is an important step in the actual application of these devices in photonic integrated circuit

Approximations for the delivery splitting model

Consumer Demand;Operational Research;Stocks

Phenomenological fingerprints of four meditations: Differential state changes in affect, mind-wandering, meta-cognition and interoception before and after daily practice across nine months of training

Despite increasing interest in the effects of mental training practices such as meditation, there is much ambiguity regarding whether and to what extent the various types of mental practice have differential effects on psychological change. To address this gap, we compare the effects of four common meditation practices on measures of state change in affect, mind-wandering, meta-cognition, and interoception. In the context of a 9-month mental training program called the ReSource Project, 229 mid-life adults (mean age 41) provided daily reports before and after meditation practice. Participants received training in the following three successive modules: the first module (presence) included breathing meditation and body scan, the second (affect) included loving-kindness meditation, and the third (perspective) included observing-thought meditation. Using multilevel modeling, we found that body scan led to the greatest state increase in interoceptive awareness and the greatest decrease in thought content, loving-kindness meditation led to the greatest increase in feelings of warmth and positive thoughts about others, and observing-thought meditation led to the greatest increase in meta-cognitive awareness. All practices, including breathing meditation, increased positivity of affect, energy, and present focus and decreased thought distraction. Complementary network analysis of intervariate relationships revealed distinct phenomenological clusters of psychological change congruent with the content of each practice. These findings together suggest that although different meditation practices may have common beneficial effects, each practice can also be characterized by a distinct short-term psychological fingerprint, the latter having important implications for the use of meditative practices in different intervention contexts and with different populations

Distributed NEGF Algorithms for the Simulation of Nanoelectronic Devices with Scattering

Through the Non-Equilibrium Green's Function (NEGF) formalism, quantum-scale device simulation can be performed with the inclusion of electron-phonon scattering. However, the simulation of realistically sized devices under the NEGF formalism typically requires prohibitive amounts of memory and computation time. Two of the most demanding computational problems for NEGF simulation involve mathematical operations with structured matrices called semiseparable matrices. In this work, we present parallel approaches for these computational problems which allow for efficient distribution of both memory and computation based upon the underlying device structure. This is critical when simulating realistically sized devices due to the aforementioned computational burdens. First, we consider determining a distributed compact representation for the retarded Green's function matrix $G^{R}$. This compact representation is exact and allows for any entry in the matrix to be generated through the inherent semiseparable structure. The second parallel operation allows for the computation of electron density and current characteristics for the device. Specifically, matrix products between the distributed representation for the semiseparable matrix $G^{R}$ and the self-energy scattering terms in $\Sigma^{<}$ produce the less-than Green's function $G^{<}$. As an illustration of the computational efficiency of our approach, we stably generate the mobility for nanowires with cross-sectional sizes of up to 4.5nm, assuming an atomistic model with scattering