China’s Local Government Debt and Economic Growth

This paper explores the impact of China’s local government debt on economic growth. This analysis, based on a panel of 31 provinces over 14 years, takes into account a broad range of economic growth determinants as well as various estimation issues including heteroskedascity and omitted variable. The empirical results suggest an inverse relationship between China’s local government debt and economic growth, controlling for other determinants of growth: on average, a 10 percentage point increase in the debt-to-GDP ratio is associated with a slowdown in annual real per capita GDP growth of around 0.27 percentage points per year

Yang monopoles and emergent three-dimensional topological defects in interacting bosons

Yang monopole as a zero-dimensional topological defect has been well established in multiple fields in physics. However, it remains an intriguing question to understand interaction effects on Yang monopoles. Here, we show that collective motions of many interacting bosons give rise to exotic topological defects that are distinct from Yang monopoles seen by a single particle. Whereas interactions may distribute Yang monopoles in the parameter space or glue them to a single giant one of multiple charges, three-dimensional topological defects also arise from continuous manifolds of degenerate many-body eigenstates. Their projections in lower dimensions lead to knotted nodal lines and nodal rings. Our results suggest that ultracold bosonic atoms can be used to create emergent topological defects and directly measure topological invariant that are not easy to access in solids.Comment: 6 pages (2 figures) + 7 pages (2 figures); accepted draft; fixed link

Embedding of Analytic Quasi-Periodic Cocycles into Analytic Quasi-Periodic Linear Systems and its Applications

In this paper, we prove that any analytic quasi-periodic cocycle close to constant is the Poincar\'{e} map of an analytic quasi-periodic linear system close to constant. With this local embedding theorem, we get fruitful new results. We show that the almost reducibility of an analytic quasi-periodic linear system is equivalent to the almost reducibility of its corresponding Poincar\'e cocycle. By the local embedding theorem and the equivalence, we transfer the recent local almost reducibility results of quasi-periodic linear systems \cite{HoY} to quasi-periodic cocycles, and the global reducibility results of quasi-periodic cocycles \cite{A,AFK} to quasi-periodic linear systems. Finally, we give a positive answer to a question of \cite{AFK} and use it to prove Anderson localization results for long-range quasi-periodic operator with Liouvillean frequency, which gives a new proof of \cite{AJ05,AJ08,BJ02}. The method developed in our paper can also be used to prove some nonlinear local embedding results.Comment: 28 pages, no figur

Universal Thermometry for Quantum Simulation

Quantum simulation is a highly ambitious program in cold atom research currently being pursued in laboratories worldwide. The goal is to use cold atoms in optical lattice to simulate models for unsolved strongly correlated systems, so as to deduce their properties directly from experimental data. An important step in this effort is to determine the temperature of the system, which is essential for deducing all thermodynamic functions. This step, however, remains difficult for lattice systems at the moment. Here, we propose a method based on a generalized fluctuation-dissipation theorem. It does not reply on numerical simulations and is a universal thermometry for all quantum gases systems including mixtures and spinor gases. It is also unaffected by photon shot noise.Comment: 4 pages, 3 figures, title, abstract and introduction modifie