Publications (15)
Ground-state phase diagram of the three-band Hubbard model from density matrix embedding theory
Zhi-Hao Cui, Chong Sun, Ushnish Ray +3
We determine the ground-state phase diagram of the three-band Hubbard model across a range of model parameters using density matrix embedding theory. We study the atomic-scale natu…
Exact fluctuations of nonequilibrium steady states from approximate auxiliary dynamics
Ushnish Ray, Garnet Kin-Lic Chan, David T. Limmer
We describe a framework to significantly reduce the computational effort to evaluate large deviation functions of time integrated observables within nonequilibrium steady states. W…
Constructing Auxiliary Dynamics for Nonequilibrium Stationary States by Variance Minimization
Ushnish Ray, Garnet Kin-Lic Chan
We present a strategy to construct guiding distribution functions (GDFs) based on variance minimization. Auxiliary dynamics via GDFs mitigates the exponential growth of variance as…
Towards the solution of the many-electron problem in real materials: equation of state of the hydrogen chain with state-of-the-art many-body methods
Mario Motta, David M. Ceperley, Garnet Kin-Lic Chan +18
We present numerical results for the equation of state of an infinite chain of hydrogen atoms. A variety of modern many-body methods are employed, with exhaustive cross-checks and…
Numerical simulation of thermal noise in Josephson circuits
Kenneth Segall, Dan Schult, Ushnish Ray +1
We present a method to numerically add thermal noise to the equations of motion for a circuit of Josephson junctions. A new noise term, which we call "linearly interpolated Gaussia…
Dysprosium magneto-optical traps
Seo Ho Youn, Mingwu Lu, Ushnish Ray +1
Magneto-optical traps (MOTs) of highly magnetic lanthanides open the door to explorations of novel phases of strongly correlated matter such as lattice supersolids and quantum liqu…
Importance sampling large deviations in nonequilibrium steady states. I
Ushnish Ray, Garnet Kin-Lic Chan, David T. Limmer
Large deviation functions contain information on the stability and response of systems driven into nonequilibrium steady states, and in such a way are similar to free energies for…
Properties of the Superfluid in the Disordered Bose-Hubbard Model
Bruno R. de Abreu, Ushnish Ray, Silvio A. Vitiello +1
We investigate the properties of the superfluid phase in the three-dimensional disordered Bose-Hubbard model using Quantum Monte-Carlo simulations. The phase diagram is generated u…
Ground-state properties of the hydrogen chain: insulator-to-metal transition, dimerization, and magnetic phases
Mario Motta, Claudio Genovese, Fengjie Ma +14
Accurate and predictive computations of the quantum-mechanical behavior of many interacting electrons in realistic atomic environments are critical for the theoretical design of ma…
Metastable Bose-Einstein Condensation in a Strongly Correlated Optical Lattice
David McKay, Ushnish Ray, Stefan Natu +3
We experimentally and theoretically study the peak fraction of a Bose-Einstein condensate loaded into a cubic optical lattice as the lattice potential depth and entropy per particl…
Dynamical phase behavior of the single- and multi-lane asymmetric simple exclusion process via matrix product states
Phillip Helms, Ushnish Ray, Garnet Kin-Lic Chan
We analyze the dynamical phases of the current-biased 1D and multi-lane open asymmetric simple exclusion processes (ASEP), using matrix product states and the density matrix renorm…
Finite temperature density matrix embedding theory
Chong Sun, Ushnish Ray, Zhi-Hao Cui +3
We describe a formulation of the density matrix embedding theory at finite temperature. We present a generalization of the ground-state bath orbital construction that embeds a mean…
Revealing the Condensate and Non-Condensate Distributions in the Inhomogeneous Bose-Hubbard Model
Ushnish Ray, David M. Ceperley
We calculate the condensate fraction and the condensate and non-condensate spatial and momentum distribution of the Bose-Hubbard model in a trap. From our results, it is evident th…
Direct comparison of many-body methods for realistic electronic Hamiltonians
Kiel T. Williams, Yuan Yao, Jia Li +22
A large collaboration carefully benchmarks 20 first principles many-body electronic structure methods on a test set of 7 transition metal atoms, and their ions and monoxides. Good…
Heat current fluctuations and anomalous transport in low dimensional carbon lattices
Ushnish Ray, David T. Limmer
Molecular dynamics simulations and nonequilibrium importance sampling are used to study the heat transport of low dimensional carbon lattices. For both carbon nanotubes and graphen…