Stephan Haas Principal Investigator Email: shaas@usc.edu Phone: (213) 740-4528 Office: SSC 211A Working on: Quantum Magnetism Superconductivity Adaptive Quantum Design Quantum Information Theory Personal Website

I am interested in topics related to nanoscience, quantum magnetism, and unconventional superconductivity. My research group investigates microscopic models of interacting electronic systems, using numerical techniques such as Quantum Monte Carlo to study their phase diagrams, thermodynamics, and excitation spectra. Recently, we have implemented the Stochastic Series Expansion Method to examine field induced phase transitions in quantum spin liquids, developed optimization algorithms to construct nanoscale opto-electronic devices, and applied BCS theory to investigate the consequences of unconventional superconductivity in strongly correlated materials. Our work is connected to experiments in the fields of nano-photonics, quantum antiferromagnetism, and high-temperature superconductivity.

Talks Given:

• Adaptive Quantum Design for Nanoscience

Papers Written:

2009:

• Scaling of the fidelity susceptibility in a disordered quantum spin chain
  N. T. Jacobson, S. Garnerone, S. Haas, P. Zanardi, Phys. Rev. B 79, 184427 (2009)

• Electron-phonon bound states and impurity band formation in quantum wells
  B.P.W. de Oliveira and S. Haas, Phys. Rev. B 79, 155102 (2009)

• Magnetic and metallic state at intermediate Hubbard U coupling in multiorbital models for undoped iron pnictides
  R. Yu, K.T. Trinh, A. Moreo, M. Daghofer, J. A. Riera, S. Haas, and E. Dagotto, Phys. Rev. B 79, 104510 (2009)

• Fidelity in topological quantum phases of matter
  S. Garnerone, D. Abasto, S. Haas, and P. Zanardi, Phys. Rev. A 79, 032302 (2009)

• Effects of Strong Correlations and Disorder in d-Wave Superconductors
  M. Rigol, B.S. Shastry, and S. Haas, Phys. Rev. B 79, 052502 (2009)

• Quantum fluctuations in small lasers
  K. Roy-Choudhury, S. Haas, and A.F.J. Levi, Phys. Rev. Lett. 102, 053902 (2009)

• Fidelity Approach to the Disordered Quantum XY Model
  S. Garnerone, N.T. Jacobson, S. Haas, and P. Zanardi, Phys. Rev. Lett. 102, 057205 (2009)

• Field induced disordered-local-moment phase in site-diluted spin-gap antiferromagnets
  R.Yu, T. Roscilde, and S. Haas, New J. Phys. 10, 013034 (2008)

• Optimal control of electromagnetic field using metallic nanoclusters
  I. Grigorenko, S. Haas, A. Balatsky and A.F.J. Levi, New J. Phys. 10, 043017 (2008)

• Scaling analysis and application: Phase diagram of magnetic nanorings and elliptical nanoparticles
  W. Zhang, R. Singh, N. Bray-Ali, and S. Haas, Phys. Rev. B 77, 144428 (2008)

• Entanglement entropy in the two-dimensional random transverse field Ising model
  R. Yu, H. Saleur, and S. Haas, Phys. Rev. B 77, 140402 (2008)

• Entanglement, fidelity, and topological entropy in a quantum phase transition to topological order
  A. Hamma, W. Zhang, S. Haas, and D. A. Lidar, Phys. Rev. B 77, 155111 (2008)

• Formation of collective excitations in quasi-one-dimensional metallic nanostructures: size and density dependence
  A. Cassidy, I. Grigorenko, and S. Haas, Phys. Rev. B 77, 245404 (2008)

• Subarea law of entanglement in nodal fermionic systems
  L. Ding, N. Bray-Ali, R. Yu, and S. Haas, Phys. Rev. Lett. 100, 215701 (2008)

• Entanglement, fidelity, and topological entropy in a quantum phase transition to topological order
  A. Hamma, W. Zhang, S. Haas, and D. A. Lidar, Phys. Rev. B 77, 155111 (2008)

• Disorder-enhanced phase coherence in trapped bosons on optical lattices
  P. Sengupta, A. Raghavan, and S. Haas, New. J. Phys. 9, 103 (2007)

• Mott glass in site-diluted S=1 antiferromagnets with single-ion anisotropy
  T. Roscilde and S. Haas, Phys. Rev. Lett. 99, 047305 (2007).

• Anatomy of Gossamer superconductivity
  S. Haas, K. Maki, T. Dahm and P. Thalmeier, Curr. Appl. Phys. 7 , 64 (2007)

• T_{1}^{-1} peak near Tc in unconventional Bardeen-Cooper-Schrieffer superconductors
  D. Parker and S. Haas, Phys. Rev. B 75, 052501 (2007)

• Quantum Glass Phases in the Disordered Bose-Hubbard Model
  P. Sengupta and S. Haas, Phys. Rev. Lett. 99, 050403 (2007)

• Generalized cuprate gap symmetry and higher d-wave harmonics: Effects of correlation length, doping, temperature, and impurity scattering
  D. Parker, S. Haas, and A.V. Balatsky, Phys. Rev. B 76, 104503 (2007).

• Synthesis of Electron Transmission in Nanoscale Semiconductor Devices
  P. Schmidt, S. Haas, and A.F.J. Levi, Appl. Phys. Lett. 88, 013502 (2006)

• Quantum disorder and Griffiths singularities in bond-diluted two-dimensional Heisenberg antiferromagnets
  R. Yu, T. Roscilde, and S. Haas, Phys. Rev. B 73, 064406 (2006)

• Scaling Behavior of Entanglement in Two- and Three-Dimensional Free Fermions
  W. Li, L. Ding, R. Yu, T. Roscilde, and S. Haas, Phys. Rev. B 74 , 073103 (2006)

• Electromagnetic response of broken-symmetry nano-scale clusters
  I. Grigorenko, S. Haas, and A.F.J. Levi, Phys. Rev. Lett. 97 , 036806(2006)

• BCS theory of unconventional superconductivity in PrOs4Sb12
  D. Parker, S. Haas, K. Maki, Physica B 378 , 902 (2006)

• New world of Gossamer superconductivity
  K. Maki, S. Haas, D. Parker, B. Dora and A. Virosztek, Phys. Stat. Sol. (c) 3 9, 3156 (2006)

• Gossamer superconductivity, new paradigm?
  H. Won, S. Haas, K. Maki, D. Parker, B. Dora, and A. Virosztek, Phys. Stat. Sol. (b) 243 1, 37 (2006)

• Bose–Einstein condensation versus localization of bosonic quasiparticles in disordered weakly-coupled dimer antiferromagnets
  T. Roscilde and S. Haas, J. Phys. B: At. Mol. Opt. Phys. 39 , S153 (2006)

• Quantum phase transition in spin systems studied through entanglement estimators
  A. Fubini, S. Haas, T. Roscilde, V. Tognetti, and P. Verucchi, Open Systems \& Information Dynamics 13, 445 (2006)

• Entanglement and Factorized Ground States in Two-Dimensional Quantum Antiferromagnets
  T. Roscilde, P. Verrucchi, A. Fubini, S. Haas, and V. Tognetti, Phys. Rev. Lett. 94, 147208 (2005)

• Quantum percolation in two-dimensional antiferromagnets
  R. Yu, T. Roscilde, and S. Haas, Phys. Rev. Lett. 94, 197204 (2005)

• Quantum Phase Transitions in Coupled Dimer Compounds
  O. Nohadani, S. Wessel, and S. Haas, Phys. Rev. B 72, 024440 (2005)

• Synthesis for semiconductor device design
  J. Thalken, S. Haas, and A.F.J. Levi, J. Appl. Phys. 98, 044508 (2005)

• Quantum localization in bilayer Heisenberg antiferromagnets with site dilution
  T. Roscilde and S. Haas, Phys. Rev. Lett. 95, 207206 (2005)

• Bose-Glass Phases in Disordered Quantum Magnets
  O. Nohadani, S. Wessel, and S. Haas, Phys. Rev. Lett. 95, 227201 (2005)

• Quasiparticle spectrum of the hybrid s+g-wave superconductors YNi₂B₂C and LuNi₂B₂C
  K. Maki, H. Won, and S. Haas, Phys. Rev. B 69, 012502 (2004)

• Aperiodic Nano-Photonic Design
  Ioan L. Gheorma, Stephan Haas, and A.F.J. Levi, J. Appl. Phys. 95, 1420 (2004)

• Upper Critical Field and Fulde-Ferrell-Larkin-Ovchinnikov State in CeCoIn₅
  H. Won, K. Maki, S. Haas, N. Oelscher, F. Weickert, and P. Gegenwart, Phys. Rev. B 69, 180504 (2004)

• Adaptive Quantum Design of Atomic Clusters
  Jason Thalken, Yu Chen, A.F.J. Levi, and S. Haas, Phys. Rev. B 69, 195410 (2004)

• Universal scaling at field-induced magnetic phase transitions
  O. Nohadani, S. Wessel, B. Normand, and S. Haas, Phys. Rev. B 69, 220402 (2004)

• Anisotropy-Induced Ordering in the Quantum J₁-J₂ Antiferromagnet
  T. Roscilde, A. Feiguin, A. L. Chernyshev, S. Liu, and S. Haas, Phys. Rev. Lett. 93, 017203 (2004)

• Adaptive Design of Excitonic Absorption in Broken-Symmetry Quantum Wells
  J. Thalken, W. Li, S. Haas, and A.F.J. Levi, Appl. Phys. Lett. 85, 121 (2004)

• Studying quantum spin systems through entanglement estimators
  T. Roscilde, P. Verrucchi, A. Fubini, S. Haas, and V. Tognetti, Phys. Rev. Lett. 93, 167203 (2004)

• Triplet superconductivity in the skutterudite PrOs₄Sb₁₂
  K. Maki, S. Haas, D. Parker, H. Won, K. Izawa, and Y. Matsuda, Eur. Phys. Lett. 68, 720 (2004)

• c-axis Josephson tunneling in d_x²-y²-wave superconductors
  Kazumi Maki and Stephan Haas, Phys. Rev. B 67, 020510 (2003)

• Quantum Antiferromagnetism in Quasicrystals
  S. Wessel, A. Jagannathan, and S. Haas, Phys. Rev. Lett. 90, 177205 (2003)

• Adaptive design of nanoscale dielectric structures for photonics
  Y. Chen, R. Yu, W. Li, O. Nohadani, S. Haas, and A.F.J. Levi, J. Appl. Phys. 94, 6065 (2003)

• Reply to Comment on ``Theory of c-axis Josephson tunneling in d_{x^2-y^2}-wave superconductors
  K. Maki and S. Haas, Phys. Rev. B 68, 226502 (2003)

• Anisotropic s-wave superconductivity in MgB₂
  S. Haas and K. Maki, Phys. Rev. B 65, 020502(R) (2002)

• Redistribution of spectral weight in Haldane chains doped with spin-1/2 moments
  S. Wessel and S. Haas, Phys. Rev. B 65, 132402 (2002)

• Effects of Andreev Scattering on the Tunneling Conductance in Superconducting MgB₂
  K. Maki, R. Gerami, and S. Haas, J. Phys. Chem. Solids 63, 1501 (2002)

• Dynamical properties of spin-orbital chains in a magnetic field
  W. Yu and S. Haas, Phys. Rev. B 63, 024423 (2001)

• Phase diagram and thermodynamic properties of the square lattice of antiferromagnetic spin-1/2 triangles in La₄Cu₃MoO₁₂
  S. Wessel and S. Haas, Phys. Rev. B 63, 140403 (2001)

• Order by Disorder from Nonmagnetic Impurities in a Two-Dimensional Quantum Spin Liquid
  S. Wessel, B. Normand, M. Sigrist, and S. Haas, Phys. Rev. Lett. 86, 1086-1089 (2001)

• Field-Induced Magnetic Order in Quantum Spin Liquids
  S. Wessel, M. Olshanii, and S. Haas, Phys. Rev. Lett. 87, 206407 (2001)

• Excitation spectra and thermodynamic response of segmented Heisenberg spin chains
  S. Wessel and S. Haas, Phys. Rev. B 61, 15262-15268 (2000)

• Three-dimensional ordering in weakly coupled antiferromagnetic ladders and chains
  S. Wessel and S. Haas, Phys. Rev. B 62, 316-323 (2000)

• Excitation spectra of structurally dimerized and spin-Peierls chains in a magnetic field
  W. Yu and S. Haas, Phys. Rev. B 62, 344-351 (2000)

• Impurity bound states and symmetry of the superconducting order parameter in Sr₂RuO₄
  K. Maki and S. Haas, Phys. Rev. B 62, 11969–11972 (2000)

• Quasiparticle Bound States around Impurities in d_x²-y²-Wave Superconductors
  S. Haas and K. Maki, Phys. Rev. Lett. 85, 2172-2175 (2000)

• Magnetic Field Induced Ordering in Quasi-One-Dimensional Quantum Magnets
  S. Wessel and S. Haas, Eur. Phys. J. B 16, 393 (2000)

• Paramagnetic Reentrance Effect in NS Proximity Cylinders
  K. Maki and S. Haas, Phys. Lett. A 272, 271 (2000)