112 research outputs found
Multidimensional super- and subradiance in waveguide quantum electrodynamics
We study the collective decay rates of multi-dimensional quantum networks in
which one-dimensional waveguides form an intersecting hyper-rectangular
lattice, with qubits located at the lattice points. We introduce and motivate
the \emph{dimensional reduction of poles} (DRoP) conjecture, which identifies
all collective decay rates of such networks via a connection to waveguides with
a one-dimensional topology (e.g. a linear chain of qubits). Using DRoP, we
consider many-body effects such as superradiance, subradiance, and bound-states
in continuum in multi-dimensional quantum networks. We find that, unlike
one-dimensional linear chains, multi-dimensional quantum networks have
superradiance in distinct levels, which we call multi-dimensional
superradiance. Furthermore, we generalize the scaling of subradiance
in a linear chain to -dimensional networks
Shape dependence of two-cylinder Renyi entropies for free bosons on a lattice
Universal scaling terms occurring in Renyi entanglement entropies have the
potential to bring new understanding to quantum critical points in free and
interacting systems. Quantitative comparisons between analytical continuum
theories and numerical calculations on lattice models play a crucial role in
advancing such studies. In this paper, we exactly calculate the universal
two-cylinder shape dependence of entanglement entropies for free bosons on
finite-size square lattices, and compare to approximate functions derived in
the continuum using several different ansatzes. Although none of these ansatzes
are exact in the thermodynamic limit, we find that numerical fits are in good
agreement with continuum functions derived using the AdS/CFT correspondence, an
extensive mutual information model, and a quantum Lifshitz model. We use fits
of our lattice data to these functions to calculate universal scalars defined
in the thin-cylinder limit, and compare to values previously obtained for the
free boson field theory in the continuum.Comment: 7 pages, 5 figures, 1 tabl
Recommended from our members
Fluctuating orders and quenched randomness in the cuprates
We study a quasi-two-dimensional classical Landau-Ginzburg-Wilson effective field theory in the presence of quenched disorder in which incommensurate charge-density wave and superconducting orders are intertwined. The disorder precludes long-range charge-density wave order, but not superconducting or nematic order. We select three representative sets of input parameters and compute the corresponding charge-density wave structure factors using both large-N techniques and classical Monte Carlo simulations. Where nematicity and superconductivity coexist at low temperature, the peak height of the charge-density wave structure factor decreases monotonically as a function of increasing temperature, unlike what is seen in x-ray experiments on YBa2Cu3O6+x. Conversely, where the thermal evolution of the charge-density wave structure factor qualitatively agrees with experiments, the nematic correlation length, computed to one-loop order, is shorter than the charge-density wave correlation length.Physic
Recommended from our members
Diamagnetism and density-wave order in the pseudogap regime of YBa 2 Cu 3 O 6 + x
Clear experimental evidence of charge density-wave correlations competing with superconducting order in YBCO have thrust their relationship with the pseudogap regime into the spotlight. To aid in characterizing the pseudogap regime, we propose a dimensionless ratio of the diamagnetic susceptibility to the correlation length of the charge density-wave correlations. Using Monte Carlo simulations, we compute this ratio on the classical model of Hayward et al. [Science 343, 1336 (2014)], which describes angular fluctuations of a multicomponent order, capturing both superconducting and density-wave correlations. We compare our results with available data on YBa2Cu3O6+x, and propose experiments to clarify the value of this dimensionless ratio using existing samples and techniques.Physic
- …