1,721,096 research outputs found
Recent progress on cluster and meron algorithms for strongly correlated systems
No full textAb initio studies of strongly interacting bosonic and fermionic systems are greatly facilitated by efficient Monte Carlo algorithms. This article emphasizes this requirement and outlines the ideas behind the construction of the cluster algorithms and illustrates them via specific examples. Numerical studies of fermionic systems at finite densities and at real-times are sometimes hindered by the infamous sign problem, which is also discussed. The construction of meron cluster algorithms, which can solve certain sign problems, is discussed. Cluster algorithms which can simulate certain pure Abelian gauge theories (realized as quantum link models) are also discussed
Form factors in the B<sub>s</sub>−−>K<i>lν</i> decays using HQET and the lattice
No full textWe report on a recent computation of theform factors in semi-leptonic decays of the Bsusing Heavy Quark Effective Theory (HQET) formalismapplied on the lattice. The connection of the form factorswith the 2-point and 3-point correlators on the lattice isexplained, and the subsequent non-perturbative renormalizationof HQET and it's matching to Nf=2 QCD is outlined. Theresults of the (static) leading-order calculation in thecontinuum limit is presented
Subleading conformal dimensions at the O(4) Wilson-Fisher fixed point
No full textIn this work we focus on computing the conformal dimension
Conformal Dimensions in the Large Charge Sectors at the O (4) Wilson-Fisher Fixed Point
Full text linkWe study the Oð4Þ Wilson-Fisher fixed point in 2 + 1 dimensions in fixed large-charge sectors identified by products of two spin-j representations (jL; jR). Using effective field theory we derive a formula for the conformal dimensions D(jL; jR) of the leading operator in terms of two constants, c3=2 and c1=2, when the sum jL þ jR is much larger than the difference jL − jR . We compute D(jL ; jR) when jL = jR with Monte Carlo calculations in a discrete formulation of the Oð4Þ lattice field theory, and show excellent agreement with the predicted formula and estimate c3=2 = 1.068(4) and c1/2 = 0.083(3)
Quantum Monte Carlo for Gauge Fields and Matter without the Fermion Determinant
Full text linkAb-initio Monte Carlo simulations of strongly-interacting fermionic systems
are plagued by the fermion sign problem, making the non-perturbative study of
many interesting regimes of dense quantum matter, or of theories of odd numbers
of fermion flavors, challenging. Moreover, typical fermion algorithms require
the computation (or sampling) of the fermion determinant. We focus instead on
the meron cluster algorithm, which can solve the fermion sign problem in a
class of models without involving the determinant. We develop and benchmark new
meron algorithms to simulate fermions coupled to and
gauge fields in the presence of appropriate four-fermi interactions. Such
algorithms can be used to uncover potential exotic properties of matter,
particularly relevant for quantum simulator experiments. We demonstrate the
emergence of the Gauss' Law at low temperatures for a model in
d.Comment: 5 pages, 4 figures, 1 tabl
Conformal Dimensions via Large Charge Expansion
Full text linkWe construct an efficient Monte Carlo algorithm that overcomes the severe signal-to-noise ratio problems and helps us to accurately compute the conformal dimensions of large- fields at the Wilson-Fisher fixed point in the (2) universality class. Using it, we verify a recent proposal that conformal dimensions of strongly coupled conformal field theories with a global (1) charge can be obtained via a series expansion in the inverse charge 1/. We find that the conformal dimensions of the lowest operator with a fixed charge are almost entirely determined by the first few terms in the series
Towards the real-time evolution of gauge-invariant and quantum link models on NISQ Hardware with error-mitigation
Full text linkPractical quantum computing holds clear promise in addressing problems not
generally tractable with classical simulation techniques, and some key
physically interesting applications are those of real-time dynamics in strongly
coupled lattice gauge theories. In this article, we benchmark the real-time
dynamics of and gauge invariant plaquette models using
noisy intermediate scale quantum (NISQ) hardware, specifically the
superconducting-qubit-based quantum IBM Q computers. We design quantum circuits
for models of increasing complexity and measure physical observables such as
the return probability to the initial state, and locally conserved charges.
NISQ hardware suffers from significant decoherence and corresponding difficulty
to interpret the results. We demonstrate the use of hardware-agnostic error
mitigation techniques, such as circuit folding methods implemented via the
Mitiq package, and show what they can achieve within the quantum volume
restrictions for the hardware. Our study provides insight into the choice of
Hamiltonians, construction of circuits, and the utility of error mitigation
methods to devise large-scale quantum computation strategies for lattice gauge
theories.Comment: 20 pages, 15 figure
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