Quantum Phase Transition in a Resonant Level Coupled to Interacting Leads

An interacting one-dimensional electron system, the Luttinger liquid, is distinct from the "conventional" Fermi liquids formed by interacting electrons in two and three dimensions. Some of its most spectacular properties are revealed in the process of electron tunneling: as a function of the applied bias or temperature the tunneling current demonstrates a non-trivial power-law suppression. Here, we create a system which emulates tunneling in a Luttinger liquid, by controlling the interaction of the tunneling electron with its environment. We further replace a single tunneling barrier with a double-barrier resonant level structure and investigate resonant tunneling between Luttinger liquids. For the first time, we observe perfect transparency of the resonant level embedded in the interacting environment, while the width of the resonance tends to zero. We argue that this unique behavior results from many-body physics of interacting electrons and signals the presence of a quantum phase transition (QPT). In our samples many parameters, including the interaction strength, can be precisely controlled; thus, we have created an attractive model system for studying quantum critical phenomena in general. Our work therefore has broadly reaching implications for understanding QPTs in more complex systems, such as cold atoms and strongly correlated bulk materials.Comment: 11 pages total (main text + supplementary

Shaping bacterial population behavior through computer-interfaced control of individual cells

This is the final version. Available from Springer Nature via the DOI in this record.Strains and data are available from the authors upon request. Custom scripts for the described setup are available as Supplementary Software.Bacteria in groups vary individually, and interact with other bacteria and the environment to produce population-level patterns of gene expression. Investigating such behavior in detail requires measuring and controlling populations at the single-cell level alongside precisely specified interactions and environmental characteristics. Here we present an automated, programmable platform that combines image-based gene expression and growth measurements with on-line optogenetic expression control for hundreds of individual Escherichia coli cells over days, in a dynamically adjustable environment. This integrated platform broadly enables experiments that bridge individual and population behaviors. We demonstrate: (i) population structuring by independent closed-loop control of gene expression in many individual cells, (ii) cell-cell variation control during antibiotic perturbation, (iii) hybrid bio-digital circuits in single cells, and freely specifiable digital communication between individual bacteria. These examples showcase the potential for real-time integration of theoretical models with measurement and control of many individual cells to investigate and engineer microbial population behavior.European Union's Seventh Frame ProgrammeAustrian Science FundAgence Nationale de la RechercheAgence Nationale de la RechercheAgence Nationale de la Recherch

State Ownership and Corporate Governance

State ownership of publicly-traded corporations remains pervasive around the world, and has been increasing in recent years. Existing literature focuses on the implications of government ownership for corporate governance and performance at the firm level. This Article, by contrast, explores the different but equally important question of whether the presence of the state as a shareholder can impose negative externalities on the corporate law regime available to the private sector. Drawing from historical experiments with government ownership in the United States, Brazil, China, and Europe, this study shows that the conflict of interest stemming from the state’s dual role as a shareholder and regulator can influence the content of corporate laws to the detriment of outside investor protection and efficiency. It thus addresses a gap in the literature on the political economy of corporate governance by incorporating the political role of the state as shareholder as another mechanism to explain the relationship between corporate ownership structures and legal investor protection. Finally, this Article explores the promise of different institutional arrangements to constrain the impact of the state’s interests as a shareholder on the corporate governance environment, and concludes by offering several policy recommendations

Controlling Fast Chaos in Delay Dynamical Systems

We introduce a novel approach for controlling fast chaos in time-delay dynamical systems and use it to control a chaotic photonic device with a characteristic time scale of ~12 ns. Our approach is a prescription for how to implement existing chaos control algorithms in a way that exploits the system's inherent time-delay and allows control even in the presence of substantial control-loop latency (the finite time it takes signals to propagate through the components in the controller). This research paves the way for applications exploiting fast control of chaos, such as chaos-based communication schemes and stabilizing the behavior of ultrafast lasers.Comment: 4 pages, 4 figures, to be published in Physical Review Letter

HUBUNGAN SOSIAL EKONOMI TERHADAP PERILAKU MENANGANI LIMBAH DOMESTIK DI SEKITAR CI SANGKUY

Penelitian ini dilatarbelakangi oleh permasalahan sosial ekonomi terhadap perilaku menangani limbah domestik yang banyak ditemukan di sekitar Ci Sangkuy tepatnya di Kelurahan Andir, yaitu di Kp. Kulalet RW 08 dan Kp. Babakan Sadar RW 10, kemudian di Desa Malakasari, yaitu di Kp. Rancabungur RW 05 dan Kp. Pameutingan RW 08. Ci Sangkuy sebagai wilayah penelitian berperan penting sebagai salah satu Sub Daerah Aliran Ci Tarum yang potensial untuk kepentingan masyarakat sekitarnya, sehingga permasalahan tersebut perlu segera ditangani bersama. Tujuan penelitian yaitu menganalisis hubungan tingkat pendidikan terhadap perilaku menangani limbah domestik di sekitar Ci Sangkuy, menganalisis hubungan tingkat pendapatan terhadap perilaku menangani limbah domestik di sekitar Ci Sangkuy, dan menganalisis hubungan mata pencaharian terhadap perilaku menangani limbah domestik di sekitar Ci Sangkuy. Metode survei digunakan dengan pendekatan geografi lingkungan. Sampel wilayah berdasarkan simple random sampling dan dihasilkan 4 RW. Sampel manusia berdasarkan purposive sampling dan proportional sampling dan dihasilkan 136 responden. Rumusan masalah dianalisis menggunakan statistika deskriptif dan Uji Korelasi Spearman Rank versi 23.0 SPSS Statistics. Hasil penelitian yaitu: ada hubungan yang sangat lemah antara tingkat pendidikan masyarakat terhadap perilaku menangani limbah domestik di sekitar Ci Sangkuy, tidak ada hubungan antara tingkat pendapatan masyarakat terhadap perilaku menangani limbah domestik di sekitar Ci Sangkuy, dan ada hubungan yang sangat lemah antara mata pencaharian masyarakat terhadap perilaku menangani limbah domestik di sekitar Ci Sangkuy. Peneliti mengajukan rekomendasi kepada semua stakeholder mulai dari pemerintah, instansi, dan masyarakat untuk lebih meningkatkan koordinasi dalam penanganan limbah domestik di sekitar Ci Sangkuy agar kualitas air dapat terjaga ;---This research background is the socio-economic problems towards the behavior of controlling domestic waste which is found mostly around the Ci Sangkuy precisely in Andir Village, i.e. at Kp. Kulalet RW 08 and Kp. Babakan Sadar RW 10, then in Malakasari Village, i.e. at Kp. Rancabungur RW 05 and Kp. Pameutingan RW 08. The Ci Sangkuy as a research area plays an important role as one of the Ci Tarum Watershed which has the potential for the benefit of the societies, so that these problem need to be controlled together. Research objectives are: (1) Analyze the correlation of education level towards behavior of controlling domestic waste around the Ci Sangkuy; (2) Analyze the correlation of income level towards behavior of controlling domestic waste around the Ci Sangkuy; (3) Analyze the correlation of livelihood towards behavior of controlling domestic waste around the Ci Sangkuy. The survey method is used with the environmental geography approach. The sample areas based on simple random sampling and produced 4 RW. Human samples based on purposive sampling and proportional sampling and produced 136 respondents. Research issues was analyzed using descriptive statistics and Spearman Rank Correlation Test by SPSS Statistics version 23.0. Results of study are: (1) There is a very weak correlation between the education level towards behavior of controlling domestic waste around Ci Sangkuy; (2) There is no correlation between the income level towards behavior of controlling domestic waste around Ci Sangkuy; (3) There is a very weak correlation between the livelihood towards behavior of controlling domestic waste around Ci Sangkuy. Researcher proposes recomendations to all stakeholders starting from the government, agencies, and societies to further improve coordination in controlling domestic waste around Ci Sangkuy so that water quality can be maintained

Stabilizing the Richardson Algorithm by Controlling Chaos

By viewing the operations of the Richardson purification algorithm as a discrete time dynamical process, we propose a method to overcome the instability of the algorithm by controlling chaos. We present theoretical analysis and numerical results on the behavior and performance of the stabilized algorithm.Comment: Send email to [email protected] or [email protected] for uuencoded tarred gzipped postscript files for the five figure

Defining and controlling double quantum dots in single-walled carbon nanotubes

We report the experimental realization of double quantum dots in single-walled carbon nanotubes. The device consists of a nanotube with source and drain contact, and three additional top-gate electrodes in between. We show that, by energizing these top-gates, it is possible to locally gate a nanotube, to create a barrier, or to tune the chemical potential of a part of the nanotube. At low temperatures we find (for three different devices) that in certain ranges of top-gate voltages our device acts as a double quantum dot, evidenced by the typical honeycomb charge stability pattern.Comment: 9 pages, 3 figure