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# Condensed Matter

This series consists of talks in the area of Condensed Matter.

## Seminar Series Events/Videos

oct 27 2015 - 3:30pm
Room #: 405
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## Orbital Angular Momentum and Spectral Flow in Two Dimensional Chiral Superfluids

Mardi sep 29, 2015
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The orbital angular momentum in a chiral superfluid has posed a paradox for several decades. For example, for the $p+ip$-wave superfluid of $N$ fermions, the total orbital angular momentum should be $N/2$ if all the fermions form Cooper pairs. On the other hand, it appears to be substantially suppressed from $N/2$, considering that only the fermions near the Fermi surface would be affected by the pairing interaction. To resolve the long-standing question, we studied chiral superfluids in a two-dimensional circular well, in terms of a conserved charge and spectral flows.

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## Matrix product operators and topological quantum order

Lundi aoû 24, 2015
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Matrix product operators form a natural language for describing topological quantum order. I will discuss how they arise as symmetries in PEPS, how anyon excitations arise as end points on them, and how the virtual indices of the MPO's provide a tensor product structure for the logical qubits in topological quantum computation.

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## Using anomaly tests to restrict crystal symmetry fractionalization in Z_2 and chiral spin liquids

Mardi aoû 11, 2015
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Using the method of flux fusion anomaly test recently developed by M. Hermele and X. Chen (arXiv:1508.00573), we show that the possible ways of fractionalize crystal symmetry is greatly restricted if we assume the spin liquid has an SU(2) spin rotation symmetry and the spinon carries a half-integer spin. For a Z_2 spin liquid, under these assumptions the vison can only take the crystal symmetry fractionalization described by the Ising gauge theory. For a chiral spin liquid these assumptions imply that the spinon must also take fractionalized quantum numbers of crystal symmetries.

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## Properties of a non-Abelian chiral spin-1 spin liquid

Mardi juil 28, 2015
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In this talk, we will analyze the properties of the bosonic $\nu = 1$ Moore-Read state when used to build a state

which is strongly believed to be a non-Abelian spin-1 chiral spin liquid state [1]. In this state the bosonic $\nu = 1$

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## Introduction to Majorana Fermions in Condensed Matter & Interpretation of recent Experiments in SmB6 using Majorana Fermi Sea

Mardi juil 21, 2015
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A pedagogic introduction will be given to: i) Emergent Majorana fermions and Majorana zero modes in certain condensed matter models and ii) Kondo insulators. This will be followed by discussion of a remarkable Quantum Oscillation Anomaly seen in recent experiments in SmB6, a Kondo insulator, by the Cambridge group [1], as providing evidence [2] for presence of Majorana fermi sea, in an unexpected place. We show a counter intuitive result that these Majorana fermions though neutral, exhibit Landau diamagnetism.

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## Topological Order Series

Jeudi juil 16, 2015
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## Topological Order Series

Mardi juil 14, 2015
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## Topological Order Series

Mardi juil 07, 2015
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## Novel Fractional Quantum Hall States in the Lowest Landau Level

Lundi juil 06, 2015
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Fractional quantum Hall effect in the sequence of filling factors n/(2np +- 1) is well understood by the integer quantum Hall effect of the composite fermions at the filling factor n. A composite fermion (CF) is a bound state of an electron and 2p number of quantized vortices. However, the experimentally observed states such as 4/11, 5/13, and 3/8 which are between 1/3 and 2/5 cannot be accommodated in the conventional noninteracting theory of composite fermions. The interaction between CFs in partially filled second effective Landau levels of CFs is important for these states.

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## Topological Order Series

Jeudi juil 02, 2015
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## RECENT PUBLIC LECTURE

### Niels Bohr: Life Behind the Physics

Speaker: Vilhelm Bohr