Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 4 of 4
Full-Text Articles in Physics
Unconventional Pairing Symmetry Of Interacting Dirac Fermions On A Π -Flux Lattice, Huaiming Guo, Ehsan Khatami, Yao Wang, Thomas Devereaux, Rajiv Singh, Richard Scalettar
Unconventional Pairing Symmetry Of Interacting Dirac Fermions On A Π -Flux Lattice, Huaiming Guo, Ehsan Khatami, Yao Wang, Thomas Devereaux, Rajiv Singh, Richard Scalettar
Faculty Publications
The pairing symmetry of interacting Dirac fermions on the π-flux lattice is studied with the determinant quantum Monte Carlo and numerical linked-cluster expansion methods. The s∗- (i.e., extended s-) and d-wave pairing symmetries, which are distinct in the conventional square lattice, are degenerate under the Landau gauge. We demonstrate that the dominant pairing channel at strong interactions is an unconventional ds∗-wave phase consisting of alternating stripes of s∗- and d-wave phases. A complementary mean-field analysis shows that while the s∗- and d-wave symmetries individually have nodes in the energy spectrum, the ds∗ channel is fully gapped. The results represent a …
Unsupervised Machine Learning Account Of Magnetic Transitions In The Hubbard Model, Kelvin Ch'ng, Nick Vazquez, Ehsan Khatami
Unsupervised Machine Learning Account Of Magnetic Transitions In The Hubbard Model, Kelvin Ch'ng, Nick Vazquez, Ehsan Khatami
Faculty Publications
We employ several unsupervised machine learning techniques, including autoencoders, random trees embedding, and t-distributed stochastic neighboring ensemble (t-SNE), to reduce the dimensionality of, and therefore classify, raw (auxiliary) spin configurations generated, through Monte Carlo simulations of small clusters, for the Ising and Fermi-Hubbard models at finite temperatures. Results from a convolutional autoencoder for the three-dimensional Ising model can be shown to produce the magnetization and the susceptibility as a function of temperature with a high degree of accuracy. Quantum fluctuations distort this picture and prevent us from making such connections between the output of the autoencoder and …
Machine Learning Phases Of Strongly Correlated Fermions, Kelvin Ch'ng, Juan Carrasquilla, Roger Melko, Ehsan Khatami
Machine Learning Phases Of Strongly Correlated Fermions, Kelvin Ch'ng, Juan Carrasquilla, Roger Melko, Ehsan Khatami
Faculty Publications
Machine learning offers an unprecedented perspective for the problem of classifying phases in condensed matter physics. We employ neural network machine learning techniques to distinguish finite-temperature phases of the strongly-correlated fermions on cubic lattices. We show that a three-dimensional convolutional network trained on auxiliary field configurations produced by quantum Monte Carlo simulations of the Hubbard model can correctly predict the magnetic phase diagram of the model at the average density of one (half filling). We then use the network, trained at half filling, to explore the trend in the transition temperature as the system is doped away from half filling. …
Observation Of Antiferromagnetic Correlations In The Hubbard Model With Ultracold Atoms, Russell Hart, Pedro Duarte, Tsung-Lin Yang, Xinxing Liu, Thereza Paiva, Ehsan Khatami, Richard Scalettar, Nandini Trivedi, David Huse, Randall Hulet
Observation Of Antiferromagnetic Correlations In The Hubbard Model With Ultracold Atoms, Russell Hart, Pedro Duarte, Tsung-Lin Yang, Xinxing Liu, Thereza Paiva, Ehsan Khatami, Richard Scalettar, Nandini Trivedi, David Huse, Randall Hulet
Faculty Publications
Ultracold atoms in optical lattices have great potential to contribute to a better understanding of some of the most important issues in many-body physics, such as high-temperature superconductivity. The Hubbard model—a simplified representation of fermions moving on a periodic lattice—is thought to describe the essential details of copper oxide superconductivity. This model describes many of the features shared by the copper oxides, including an interaction-driven Mott insulating state and an antiferromagnetic (AFM) state. Optical lattices filled with a two-spin-component Fermi gas of ultracold atoms can faithfully realize the Hubbard model with readily tunable parameters, and thus provide a platform for …