The experimental realization of a quantum spin liquid ground state in two-dimensions-a new form of matter with no conventional broken symmetry-has been under intensive investigations for decades. Recently, this novel state has likely been discovered. I will talk about my successful crystal growth of Herbertsmithite ZnCu3(OH)6Cl2-a strongly…

Abstract: Equilibrium thermal noise is known to destroy the scale invariance of quantum critical points, through the introduction of a finite thermal length. What are the effects of non-equilibrium time-dependent noise? In two recent papers[1-2] we have considered two specific cases relevant to experiments on low-dimensional quantum systems, by…

Abstract: We provide a microscopic understanding of the nucleation of topological quantum liquids for interacting non-Abelian anyons by making an explicit connection between the microscopics of the pairwise interactions – typically showing RKKY-type behavior oscillating in sign, but decaying exponentially with distance – and the nature of the…

Abstract: The LaAlO3/SrTiO3 heterostructure is a potential candidate for a high mobility two-dimensional electron system with novel electronic and magnetic properties. Though LaAlO3 and SrTiO3 are both large-gap band insulators, the interface is conductive, and even superconducting below 200 mK. Negative electronic compressibility is observed as…

Abstract: Since the pioneering proposal by Anderson that the superconducting state of high-Tc cuprates can be described by the resonanting-valence-bond (RVB) state, a number of important results to support the idea were obtained by using the variational approach to study the t-J model. However, two major issues were not addressed at the…

Abstract: Time-reversal invariant band insulators can be separated into two categories: `ordinary' insulators and `topological' insulators. Topological band insulators have low-energy edge modes that cannot be gapped without violating time-reversal symmetry, while ordinary insulators do not. A natural question is whether more exotic time-…

Abstract: The COPHEE end station at the Swiss Light Source can provide the three spatial components of the expectation value of the spin polarization. Combined with our vectorial analysis method this allows us to determine the spin polarization vector for any region in momentum space. After an introduction to this technique I will demonstrate its…

Abstract: The fundamental collective degree of freedom of fractional quantum Hall states is identified as a unimodular two-dimensional spatial metric that characterizes the local shape of the correlations of the incompressible fluid. Its quantum fluctuations are controlled by a topologically-quantized“guiding-center spinâ€

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Abstract: Understanding the interplay between the phases present in a high-temperature superconductor (superconducting, pseudogap, strange metal and Fermi-liquid-like) is the key-concept for shining light on the nature of the superconductivity mechanisms in copper-oxide based superconductors. In this seminar I will discuss this physics by…

Abstract: A rare opportunity to explore the fate of a three-dimensional gas of highly mobile electrons confined to their lowest Landau levels is provided by elemental semi-metals. Coulomb interaction, neglected in the band picture, is expected to become significant in this extreme quantum limit, with poorly understood consequences. Our study of…

Title: Strongly correlated photons in coupled cavity/circuit QED systems Abstract: Motivated by the recent success of engineering strong light-matter interaction in various cavity/circuit QED architectures, there has been a surge of interest in realizing condensed matter-like systems with photonic systems. One of the most…

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Topological phases of matter, apart from being a fundamental phenomenon in quantum physics, has a potential application in fault tolerant quantum computation. The fractional quantum Hall effect to date is the most clearly established example of a topological phase. Topological phases are notable for possessing exotic particles as elementary…