## Condensed Matter Seminar,
Regular time and place: Thursdays at 11:30am in Physics 298. |

2018/11/15 |
Fabio Altomare (D-Wave Systems)"D-Wave quantum annealer as a quantum simulator"D-Wave Systems builds superconducting quantum annealing processors that are primarily intended to be used for solving classical computation problems such as optimization and sampling. However, recent studies have shown how this computing platform can be used as a programmable quantum magnet that can be used to simulate physical systems relevant to the field of condensed matter physics. This lecture will provide a brief overview of D-Wave's technology, a summary of recently published quantum magnetism experiments, and a look ahead at next-generation quantum annealing processors. [1] A. D. King et al., Nature 560, 456 (2018) [2] R. Harris et al., Science 361, 162 (2018) Host: Albert Chang, Thomas Barthel |

2018/11/29 |
Arthur P. Ramirez (UC Santa Cruz)"Transport in undoped Weyl semimetals and a new type of spin glass"Two topics will be discussed. The first addresses transport in undoped Weyl semimetals (WSMs). Despite their name and the behavior of most WSMs, these materials should exhibit "semiconducting" temperature dependent resistivity, drho/dT<0, when undoped. We show that this form is obeyed in the rare-earth iridate pyrochlores, R2Ir2O7, in stoichiometric samples. We also show that for R = Yttrium, rho~1/T^4, consistent with a theory of charged impurity scattering, but extending into a temperature range where k_F l << 1, suggesting behavior of a "bad" WSM. The second topic will address an unusual spin glass, pseudobrookite Fe2TiO5 in which an Ising anisotropy develops due to interactions. This presents a second example of "quasi-spin" glass. Host: Harold Baranger |

2018/12/06 |
Luiz Henrique Bugatti Guessi (Universidade de Sao Paulo, Duke)"Correlation effects in the emergence of bound states in the continuum"Bound states in the continuum (BICs) are states with localized wave-functions even though lying in the continuum. Here, we explore theoretically the emergence of BICs in a system comprising two identical quantum dots side-coupled to a quantum wire. The dots are symmetrically coupled to the site at the center of the wire and to its nearest neighbors. Taking advantage of the parity symmetry, we work with the bonding and the anti-bonding (AB) levels resulting from the symmetric and antisymmetric combinations of the dot levels. Based on the two-impurity Anderson Hamiltonian and the numerical renormalization group method, our results show that the AB orbital is a BIC in the non-interacting limit. The AB orbital is broadened due the spin-spin and spin-flip interactions between the two orbitals. In addition, if the coupling is particle-hole asymmetric, the magnetic moments of the dots can form a triplet or a singlet state due to the RKKY interaction, affecting the formation of the Kondo cloud. In the strong asymmetric coupling limit, the AB orbital is reduced to a singly occupied level that is decoupled from the continuum, i.e., a bound spin states in the continuum. |

2018/12/13 |
Journal club ft.
Xin Zhang"Phase transitions in driven-dissipative quantum optical systems"[1] P.D. Drummond and D.F. Walls, J. Phys. A: Math. Gen. 13, 725 (1980) [2] W. Casteels, F. Storme, A. Le Boité, and C. Ciuti, Phys. Rev. A 93, 033824 (2016) [3] W. Casteels, R. Fazio, and C. Ciuti, Phys. Rev. A 95, 012128 (2017) [4] T. Fink, A. Schade, S. Höfling, C. Schneider, A. Imamoglu, Nature Physics 14, 365 (2018) |

2019/02/07 |
Elizabeth L, Green (Helmholtz-Zentrum Dresden-Rossendorf)title and abstract t.b.a.Host: Sara Haravifard |

2018/11/08 |
Nicholas P. Butch (NIST, UMD College Park)"Spin polarized half-gapped superconductivity" | |

2018/10/11 |
Seyed M. Koohpayeh (Johns Hopkins University)"Development, synthesis, and bulk crystal growth of novel/quantum materials" | |

2018/05/10 |
Oleg L. Berman (City University of New York)"Exciton Bose-Einstein condensation and superfluidity in two-dimensional nanomaterials" | |

2018/05/07 |
Hannes Pichler (Harvard University), Unusual weekday: Monday!"Universal photonic quantum computation via time-delayed feedback" | |

2018/05/01 |
Chun Ning (Jeanie) Lau (Ohio State University), Unusual weekday: Tuesday!"Spin, charge and heat transport in low-dimensional materials" | |

2018/04/26 |
Adolfo del Campo (University of Massachusetts Boston)"Tailoring the dynamics of isolated and open quantum systems" | |

2018/04/19 |
Charles L. Kane (University of Pennsylvania)"Topological superconductivity from Majorana to Fibonacci" | |

2018/04/17 |
Dan Shahar (Weizmann Institute of Science), Unusual weekday: Tuesday!"Hot superconductors and cold insulators" | |

2018/04/10 |
Manuel Houzet (Université Grenoble Alpes and CEA), Unusual weekday: Tuesday!"Non-equilibrium quasi-particles in disordered superconductors" | |

2018/03/29 |
Journal club ft.
Anne Draelos"Superconductivity and Mott insulating behavior in twisted bilayer graphene" | |

2018/03/22 |
Carlos A. R. Sa de Melo (Georgia Tech)"Color superfluidity of neutral ultracold fermions in the presence of color-orbit and color-flip fields" | |

2018/03/15 |
Journal club ft.
Xin Zhang"Variational approach to non-equilibrium quantum impurity problems" | |

2018/02/22 |
James R. Williams (University of Maryland, College Park)"Using Josephson junctions to probe quantum materials" | |

2018/02/15 |
Journal club ft.
Gu Zhang"Geometric phase at quantum phase transitions" | |

2018/01/11 |
Sho Yaida (Duke University)"Novel phase transition within amorphous solids" | |

2017/12/07 |
Thomas Barthel (Duke University)"Fractal structures in the phase diagram of the honeycomb-lattice quantum dimer model" | |

2017/11/16 |
Aashish Clerk (University of Chicago)"Photonic analogues of topological superconductors" | |

2017/10/26 |
Dmitri Khveshchenko (UNC Chapel Hill)"Thickening and sickening the Sachdev-Ye-Kitaev model" | |

2017/10/12 |
Giuseppe Calajo (TU Wien)"Atom-light interactions in slow-light waveguide QED" | |

2017/09/21 |
Kirill Shtengel (University of California Riverside)"Designer non-Abelian anyons and exotic quantum circuitry" | |

2017/09/07 |
Elbio R. A. Dagotto (University of Tennessee and ORNL)"Computational studies of iron-based high critical temperature superconductors" | |

2017/09/05 |
Václav Janiš (Charles University in Prague, Academy of Sciences of the Czech Republic), Unusual weekday: Tuesday!"Quantum dot attached to superconducting leads: Andreev bound states and 0-pi transition" | |

2017/05/25 |
Journal club ft.
Gu Zhang"Transport through many-terminal Majorana islands" | |

2017/05/11 |
Journal club ft.
Xin Zhang"Topology of density matrices" | |

2017/04/20 |
Zhenzhong Shi (National High Magnetic Field Lab)"Hidden order of Cooper pairs in a striped cuprate at high magnetic fields" | |

2017/04/06 |
Subir Sachdev (Harvard University)"Confinement transitions of Ising gauge theories" | |

2017/03/30 |
Leo Fang (Duke University)"Non-Markovian dynamics of a qubit due to photon scattering in a waveguide" | |

2017/03/23 |
Francesco Ciccarello (University of Palermo, NEST, Duke)"Quantum 'non-Markovianity': new definitions and some recent developments" | |

2017/02/16 |
Po-Hao Huang (Boston University)"Coupled spin-1/2 ladders as microscopic models for non-Abelian chiral spin liquids" | |

2017/01/12 |
Dong Liu (Microsoft Station Q)"Majorana Search: Challenges and opportunities" | |

2016/12/01 |
Alexander Kemper (NC State University)"Understanding complex materials using nonequilibrium spectroscopy: What can theory tell?" | |

2016/11/22 |
Informal seminar ft.
Ben Lawson (University of Michigan), Unusual time: Tuesday, 1:30pm!"Torque magnetometry on topological superconductor candidate doped Bi2Se3" | |

2016/11/22 |
Informal seminar ft.
Elbio R. A. Dagotto (University of Tennessee and ORNL), Unusual time: Tuesday, 9:30am! | |

2016/11/15 |
Kin Chung Fong (Raytheon BBN Technologies), Unusual weekday: Tuesday!"Listening to the noise of Dirac fluid in graphene" | |

2016/11/10 |
Shiwei Zhang (College of William and Mary)"Computing electron correlation effects: an auxiliary-field perspective" | |

2016/10/17 |
Denis Ullmo (LPTMS, Université Paris Sud), Unusual weekday: Monday!"Schrödinger approach to Mean Field Games" | |

2016/10/11 |
Yoshitomo Kamiya (CMT Laboratory, RIKEN), Unusual weekday: Tuesday!"Multiferroics by design with frustrated molecular magnets" | |

2016/09/29 |
Carlos J. Bolech (University of Cincinnati)"Consistency between bosonization and nonequilibrium transport setups" | |

2016/09/22 |
Siyuan Dai (UC San Diego)"Hyperbolic phonon polaritons in hexagonal boron nitride" | |

2016/07/18 |
Huaixiu Zheng (Yale University), Unusual weekday: Monday!"Quantum state smoothing for single microwave photon detection" | |

2016/04/07 |
Waseem S. Bakr (Princeton University)"Strongly-interacting fermionic superfluids: spin-imbalance, lower dimensionality and topological defects" | |

2016/03/24 |
Konstantin Matveev (Argonne National Lab)"Electrical and thermal transport in inhomogeneous Luttinger liquids" | |

2016/03/21 |
Hao Zhang (TU Delft), Unusual weekday: Monday!"Majorana zero modes in InSb nanowires" | |

2016/03/10 |
Eduardo Novais (Universidade Federal do ABC, Brazil)"Fidelity of a quantum state protected by the surface code at finite temperatures" | |

2016/02/29 |
Journal club ft.
Moritz Binder, Unusual weekday & place: Monday, Physics 205!"Identification of Hamiltonians and Liouvillians" | |

2016/02/25 |
Adriana Moreo (University of Tennessee, ORNL)"Robust nematic state in electron-doped pnictides induced by isotropic quenched disorder" | |

2016/02/11 |
Arnab Banerjee (Oak Ridge National Laboratory)"In search of exotic fermions in spin-liquids - the case of a-RuCl3" | |

2016/01/21 |
Gu Zhang (Duke University)"Rescuing a quantum phase transition with quantum noise" | |

2015/12/07 |
Journal club ft.
Moritz Binder, Unusual weekday: Monday!"Photonic quantum circuits with time delays" | |

2015/11/19 |
Daniel Silevitch (University of Chicago, Caltech)"Tunable ground states in a model quantum magnet" | |

2015/11/12 |
Catherine Marcoux (Duke University)"Limit-periodic structures: self-assembly and sparse vibrational modes" | |

2015/10/22 |
Adrian E. Feiguin (Northeastern University, Boston)"Building and understanding magnetic nano-structures, one atom at a time" | |

2015/10/08 |
Christopher Wilson (University of Waterloo)"Quantum electrodynamics in 1D using a superconducting artificial atom" | |

2015/10/01 |
François Amet (Appalachian State University)"Superconductivity in the quantum Hall regime" | |

2015/09/24 |
Journal club ft.
Gu Zhang"Fate of the Kondo effect and impurity quantum phase transitions through the lens of fidelity susceptibility" | |

2015/09/10 |
Journal club ft.
Leo Fang"A chemical potential for light" | |

2015/09/03 |
Journal club ft.
Anne Watson"Hot-carrier Seebeck effect: Diffusion and remote detection of hot carriers in graphene" |

have a nice day!