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216

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## Publications

Publications (216)

In this work we propose a novel solid-state platform for creating quantum simulators based on implanted $S=1$ spin centers in semiconductors. We show that under the presence of an external magnetic field, an array of $S=1$ spin centers interacting through magnetic dipole-dipole interaction can be mapped into an effective spin-half system equivalent...

Some of the most problematic issues that limit the implementation of applications on Noisy Intermediate Scale Quantum (NISQ) machines are the adverse impacts of both incoherent and coherent errors. We conducted an in-depth study of coherent errors on a quantum hardware platform using a transverse field Ising model Hamiltonian as a sample user appli...

We examine the decay rate of the particle decay $B^0 \rightarrow D^- \ell^+ \nu_{\ell}$ using data collected from the Belle Collaboration. We studied three parameterizations of the form factor which describe the differential decay rate, the Caprini, Lellouch, and Neubert (CLN) parametrization, the Boyd, Grinstein, and Lebed (BGL) parametrization, a...

We discuss recent progress in Tensor Lattice Field Theory and economical, symmetry preserving, truncations suitable for quantum computations or simulations. We focus on spin and gauge models with continuous Abelian symmetries such as the Abelian Higgs model and emphasize noise-robust implementations of Gauss's law. We discuss recent progress concer...

The lattice compact Abelian Higgs model is a nonperturbative regularized formulation of low-energy scalar quantum electrodynamics. In 1+1 dimensions, this model can be quantum simulated using a ladder-shaped optical lattice with Rydberg-dressed atoms [J. Zhang et al., Phys. Rev. Lett. 121, 223201 (2018)]. In this setup, one spatial dimension is use...

The $q$-state clock model is a classical spin model that corresponds to the Ising model when $q=2$ and to the $XY$ model when $q\to\infty$. The integer-$q$ clock model has been studied extensively and has been shown to have a single phase transition when $q=2$,$3$,$4$ and two phase transitions when $q>4$.We define an extended $q$-state clock model...

We present a method to extract the phase shift of a scattering process using the real-time evolution in the early and intermediate stages of the collision in order to estimate the time delay of a wave packet. This procedure is convenient when using noisy quantum computers for which the asymptotic out-state behavior is unreachable. We demonstrate th...

Motivated by recent attempts to quantum simulate lattice models with continuous Abelian symmetries using discrete approximations, we define an extended-O(2) model by adding a γcos(qφ) term to the ordinary O(2) model with angular values restricted to a 2π interval. In the γ→∞ limit, the model becomes an extended q-state clock model that reduces to t...

The lattice compact Abelian Higgs model is a non-perturbative regularized formulation of low-energy scalar quantum electrodynamics. In 1+1 dimensions, this model can be quantum simulated using a ladder-shaped optical lattice with Rydberg-dressed atoms (Zhang et al., Phys. Rev. Lett. 121, 223201). In this setup, one spatial dimension is used to carr...

The O(2) model in Euclidean space-time is the zero-gauge-coupling limit of the compact scalar quantum electrodynamics. We obtain a dual representation of it called the charge representation. We study the quantum phase transition in the charge representation with a truncation to “spin S,” where the quantum numbers have an absolute value less than or...

We define an extended-O(2) model by adding a $\gamma \cos(q\varphi)$ term to the ordinary O(2) model with angular values restricted to a $2\pi$ interval. In the $\gamma \rightarrow \infty$ limit, the model becomes an extended $q$-state clock model that reduces to the ordinary $q$-state clock model when $q$ is an integer and otherwise is a continuat...

The O(2) model in Euclidean space-time is the zero-gauge-coupling limit of the compact scalar quantum electrodynamics. We obtain a dual representation of it called the charge representation. We study the quantum phase transition in the charge representation with a truncation to "spin $S$", where the quantum numbers have an absolute value less or eq...

We present a method to extract the phase shift of a scattering process using the real-time evolution in the early and intermediate stages of the collision in order to estimate the time delay of a wave packet. This procedure is convenient when using noisy quantum computers for which the asymptotic out-state behavior is unreachable. We demonstrate th...

We discuss the successes and limitations of statistical sampling for a sequence of models studied in the context of lattice QCD and emphasize the need for new methods to deal with finite-density and real-time evolution. We show that these lattice models can be reformulated using tensorial methods where the field integrations in the path-integral fo...

We show that standard identities and theorems for lattice models with U(1) symmetry get reexpressed discretely in the tensorial formulation of these models. We also explain the geometrical analogy between the continuous lattice equations of motion and the discrete selection rules of the tensors. We further construct a gauge-invariant transfer matri...

We construct a tensor network representation of the partition function for the massless Schwinger model on a two-dimensional lattice using staggered fermions. The tensor network representation allows us to include a topological term. Using a particular implementation of the tensor renormalization group we calculate the average plaquette and topolog...

We show that standard identities and theorems for lattice models with $U(1)$ symmetry get re-expressed discretely in the tensorial formulation of these models. We explain the geometrical analogy between the continuous lattice equations of motion and the discrete selection rules of the tensors. We construct a gauge-invariant transfer matrix in arbit...

We investigate the Joule expansion of nonintegrable quantum systems that contain bosons or spinless fermions in one-dimensional lattices. A barrier initially confines the particles to be in half of the system in a thermal state described by the canonical ensemble and is removed at time t=0. We investigate the properties of the time-evolved density...

We report updates to an ongoing lattice-QCD calculation of the form factors for the semileptonic decays $B \to \pi \ell \nu$, $B_s \to K \ell \nu$, $B \to \pi \ell^+ \ell^-$, and $B \to K \ell^+ \ell^-$. The tree-level decays $B_{(s)} \to \pi (K) \ell \nu$ enable precise determinations of the CKM matrix element $|V_{ub}|$, while the flavor-changing...

We construct a tensor network representation of the partition function for the massless Schwinger model on a two dimensional lattice using staggered fermions. The tensor network representation allows us to include a topological term. Using a particular implementation of the tensor renormalization group (HOTRG) we calculate the phase diagram of the...

We demonstrate that it is feasible to carry out a real time simulation of a quantum field theory in one spacial dimension using current quantum computers. We use the transverse Ising model in one spatial dimension with 4 sites as an example on two of IBM's quantum computers, Poughkeepsie and Boeblingen, but this methodology is easily extendable to...

We use lattice QCD to calculate the form factors f+(q2) and f0(q2) for the semileptonic decay Bs→Kℓν. Our calculation uses six MILC asqtad 2+1 flavor gauge-field ensembles with three lattice spacings. At the smallest and largest lattice spacing the light-quark sea mass is set to 1/10 the strange-quark mass. At the intermediate lattice spacing, we u...

We consider the tensor formulation of the nonlinear O(2) sigma model and its gauged version (the compact Abelian Higgs model), on a D-dimensional cubic lattice, and show that tensorial truncations are compatible with the general identities derived from the symmetries of these models. This means that the universal properties of these models can be r...

We discuss real-time evolution for the quantum Ising model in one spatial dimension with Ns sites. In the limit where the nearest-neighbor interactions J in the spatial directions are small, there is a simple physical picture where qubit states can be interpreted as approximate particle occupations. Using exact diagonalization, for initial states w...

This whitepaper is an outcome of the workshop Intersections between Nuclear Physics and Quantum Information held at Argonne National Laboratory on 28-30 March 2018 [www.phy.anl.gov/npqi2018/]. The workshop brought together 116 national and international experts in nuclear physics and quantum information science to explore opportunities for the two...

We consider the tensor formulation of the non-linear O(2) sigma model and its gauged version (the compact Abelian Higgs model), on a $D$-dimensional cubic lattice, and show that tensorial truncations are compatible with the general identities derived from the symmetries of these models. This means that the universal properties of these models can b...

We investigate the Joule expansion of nonintegrable quantum systems that contain bosons or fermions in one-dimensional lattices. A barrier initially confines the particles to be in half of the system in a thermal state described by the canonical ensemble. At long times after the barrier is removed, few-body observables can be approximated by a ther...

We discuss real time evolution for the quantum Ising model in one spatial dimension with $N_s$ sites. In the limit where the nearest neighbor interactions $J$ in the spatial directions are small, there is a simple physical picture where qubit states can be interpreted as approximate particle occupations. Using exact diagonalization, for initial sta...

We use lattice QCD to calculate the form factors $f_+(q^2)$ and $f_0(q^2)$ for the semileptonic decay $B_s\to K\ell\nu$. Our calculation uses six MILC asqtad 2+1 flavor gauge-field ensembles with three lattice spacings. At the smallest and largest lattice spacing the light-quark sea mass is set to 1/10 the strange-quark mass. At the intermediate la...

We show that the Polyakov loop of the two-dimensional lattice Abelian Higgs model can be calculated using the tensor renormalization group approach. We check the accuracy of the results using standard Monte Carlo simulations and find good agreement. We show that the energy gap produced by the insertion of the Polyakov loop obeys universal finite-si...

Using the example of configurations generated with the worm algorithm for the two-dimensional Ising model, we propose renormalization group (RG) transformations, inspired by the tensor RG, that can be applied to sets of images. We relate criticality to the logarithmic divergence of the largest principal component. We discuss the changes in link occ...

We calculate the tree-level mass spectrum for a linear sigma model describing the scalar and pseudoscalar mesons of a SU(3) local gauge theory with Dirac fermions in the fundamental representation. N1 fermions have a mass m1 and N2 a mass m2. Using recent lattice data with m1=m2 and N1+N2=8 or 12, we predict the mass splittings for m2=m1+δm. At fir...

We derived the tree level spectrum to an extension to the linear sigma model describing an EFT for an $SU(3)_c$ gauge theory with $N_f$ flavors of fermions and $N_1$ fermions have a mass $m_l$ and $N_2$ fermions have a mass $m_h$. We examined the effects of a small mass splitting on single mass data for 8 and 12 flavors of fermions corresponding to...

Using the example of configurations generated with the worm algorithm for the two-dimensional Ising model, we propose renormalization group (RG) transformations, inspired by the tensor RG, that can be applied to sets of images. We relate criticality to the logarithmic divergence of the largest principal component. We discuss the changes in link occ...

We develop a methodology to test the accuracy of lattice extrapolations of the form factors in B decays only using experimental data. We test this methodology by comparing the BGL parameterization proposed by Boyd, Grinstein, and Lebed (1996) and the BCL parameterization proposed by Bourrely Caprini and Lellouch (2008) in the context of $B \rightar...

We show that the Polyakov loop of the two-dimensional lattice Abelian Higgs model can be calculated using the tensor renormalization group approach. We check the accuracy of the results using standard Monte Carlo simulations. We show that the energy gap produced by the insertion of the Polyakov loop obeys universal finite-size scaling which persist...

We calculate the tree-level mass spectrum for a linear sigma model describing the scalar and pseudoscalar mesons of a $SU(3)$ local gauge theory with Dirac fermions in the fundamental representation. $N_1$ fermions have a mass $m_1$ and $N_2$ a mass $m_2$. Using recent lattice data with $m_1=m_2$ and $N_1+N_2$= 8 or 12, we predict the mass splittin...

We show that the gauged $O(2)$ spin model in 1+1 dimensions is a prime candidate for a first quantum simulation of a lattice gauge theory with optical lattices. Using a discrete tensor reformulation, we connect smoothly the space-time isotropic version used in most numerical simulations, to the continuous time limit corresponding to the Hamiltonian...

Using the MILC 2+1 flavor asqtad quark action ensembles, we are calculating the form factors f0 and f+ for the semileptonic Bs → Kℓv decay. A total of six ensembles with lattice spacing from ≈ 0.12 to 0.06 fm are being used. At the coarsest and finest lattice spacings, the light quark mass m’l is one-tenth the strange quark mass m’s. At the interme...

We report the status of an ongoing lattice-QCD calculation of form factors for exclusive semileptonic decays of $B$ mesons with both charged currents ($B\to\pi\ell\nu$, $B_s\to K\ell\nu$) and neutral currents ($B\to\pi\ell^+\ell^-$, $B\to K\ell^+\ell^-$). The results are important for constraining or revealing physics beyond the Standard Model. Thi...

Machine learning has been a fast growing field of research in several areas dealing with large datasets. We report recent attempts to use Renormalization Group (RG) ideas in the context of machine learning. We examine coarse graining procedures for perceptron models designed to identify the digits of the MNIST data. We discuss the correspondence be...

It is expected that when the number of light flavors of gauge theories is increased near or beyond some critical value, new and interesting behavior occurs. We discuss the qualitative properties of the RG flows for a local $SU(3)$ theory with $N_f$ light fundamental flavors for $N_f$ near 12. We discuss the realization of the chiral symmetry and re...

We consider a linear sigma model describing $2N_f^2$ bosons ($\sigma$, ${\bf a_0}$, $\eta '$ and ${\bf \pi}$) as an approximate effective theory for a $SU(3)$ local gauge theory with $N_f$ Dirac fermions in the fundamental representation. The model has a renormalizable $U(N_f)_L\bigotimes U(N_f)_R$ invariant part, which has an approximate $O(2N_f^2...

We calculate the von Neumann and R\'enyi bipartite entanglement entropy of the $O(2)$ model with a chemical potential on a 1+1 dimensional Euclidean lattice with open and periodic boundary conditions. We show that the Calabrese-Cardy conformal field theory predictions for the leading logarithmic scaling with the spatial size of these entropies are...

We discuss the reformulation of the O(2) model with a chemical potential and the Abelian Higgs model on a 1+1 dimensional space-time lattice using the Tensor Renormalization Group (TRG) method. The TRG allows exact blocking and connects smoothly the classical Lagrangian approach to the quantum Hamiltonian approach. We calculate the entanglement ent...

We demonstrate that current experiments using cold bosonic atoms trapped in one-dimensional optical lattices and designed to measure the second-order Renyi entanglement entropy S_2, can be used to verify detailed predictions of conformal field theory (CFT) and estimate the central charge c. We discuss the adiabatic preparation of the ground state a...

We compare two calculations of the particle density in the superfluid phase of the O(2) model with a chemical potential μ in 1+1 dimensions. The first relies on exact blocking formulas from the Tensor Renormalization Group (TRG) formulation of the transfer matrix. The second is a worm algorithm. We show that the particle number distributions obtain...

We present a gauge-invariant effective action for the Abelian-Higgs model in
1+1 dimensions. It is constructed by integrating out the gauge field and then
using the hopping parameter expansion. The latter is tested with Monte Carlo
simulations for small values of the scalar self-coupling. In the opposite
limit, at infinitely large self-coupling, th...

We discuss the Tensor Renormalization Group (TRG) method for the O(2) model
with a chemical potential in 1+1 dimensions with emphasis on near
gapless/conformal situations. We emphasize the role played by the late Leo
Kadanoff in the development of this theoretical framework. We describe the
entanglement entropy in the superfluid phase (see arXiv:15...

The rare decay B→πℓ+ℓ- arises from b→d flavor-changing neutral currents and could be sensitive to physics beyond the standard model. Here, we present the first ab initio QCD calculation of the B→π tensor form factor fT. Together with the vector and scalar form factors f+ and f0 from our companion work [J.A. Bailey et al., Phys. Rev. D 92, 014024 (2...

We compute the form factors for the $B \to Kl^+l^-$ semileptonic decay
process in lattice QCD using gauge-field ensembles with 2+1 flavors of sea
quark, generated by the MILC Collaboration. The ensembles span lattice spacings
from 0.12 to 0.045 fm and have multiple sea-quark masses to help control the
chiral extrapolation. The asqtad improved stagg...

We compare two calculations of the particle density in the superfluid phase
of the classical XY model with a chemical potential $\mu$ in 1+1 dimensions.The
first relies on exact blocking formulas from the Tensor Renormalization Group
(TRG) formulation of the transfer matrix. The second is a worm algorithm. We
show that the particle number distribut...

The rare decay $B\to\pi\ell^+\ell^-$ is sensitive to $b\to d$ flavor-changing
neutral currents, which could arise from physics beyond the Standard Model.
Here, we present the first $ab$-$initio$ QCD calculation of the $B\to\pi$
tensor form factor $f_T$. Together with the vector and scalar form factors
$f_+$ and $f_0$ from our companion work [J. A....

We present a gauge-invariant effective action for the Abelian Higgs model
(scalar electrodynamics) with a chemical potential $\mu$ on a 1+1 dimensional
lattice. This formulation provides an expansion in the hopping parameter
$\kappa$ which we test with Monte Carlo simulations for a broad range of the
inverse gauge coupling $\beta_{pl}$ and small va...