Article
Business, Finance
Christian M. Hafner, Helmut Herwartz
Summary: This paper proposes an extension to correlation impulse response functions (CIRF) based on a multivariate GARCH modeling framework. We find that CIRF and corresponding covariance impulse response functions can react differently and even move in opposite directions to a given shock. Due to nonlinearity, there is no analytical form available for CIRF, but we propose a straightforward algorithm to numerically estimate it. In an empirical application, we focus on the impact of the change in Ethereum's consensus protocol in 2022 on its correlation with Bitcoin.
FINANCE RESEARCH LETTERS
(2023)
Article
Astronomy & Astrophysics
Zhijin Li
Summary: This paper proposes and verifies a novel algebraic property of crossing equations, which can simplify the solving process by converting the equations into vector equations related to branching rules. It also points out that the introduction of symmetry assumptions can solve some problems in non-SO(N) symmetric theories.
Article
Chemistry, Physical
Kento Yasuda, Kenta Ishimoto, Akira Kobayashi, Li-Shing Lin, Isamu Sou, Yuto Hosaka, Shigeyuki Komura
Summary: We investigate the statistical properties of fluctuations in active systems that are governed by non-symmetric responses. In a system at thermal equilibrium, the time-correlation functions should satisfy time-reversal symmetry, but in odd Langevin systems, the anti-symmetric parts of the time-correlation functions can exist. Using the short-time asymptotic expressions of the time-correlation functions, one can estimate an odd elastic constant of an active material.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Astronomy & Astrophysics
Peter Lowdon
Summary: In this work, we discuss the general analytic characteristics of scalar correlation functions at finite temperature in local quantum field theory. We demonstrate that the locality of the fields imposes significant constraints on the spectral structure of the theory, allowing for the direct calculation of nonperturbative effects experienced by thermal particle states from Euclidean correlation functions, bypassing the inverse problem.
Article
Physics, Fluids & Plasmas
Nicolas Desbiens, Philippe Arnault, William Weens, Vincent Dubois, Guillaume Perrin
Summary: This study discusses the quantification of uncertainties in time correlation functions in molecular dynamics using the bootstrap method. The autocorrelation functions of a binary ionic mixture were chosen as a test case, with an assessment of the Darken approximation. The study also explores the effectiveness of the bootstrap method in addressing finite-size effects.
Article
Physics, Multidisciplinary
Fabian B. Kugler, Seung-Sup B. Lee, Jan von Delft
Summary: This passage discusses two approaches to studying the many-body problem, connecting results through spectral representations. Generalized spectral representations for multipoint correlation functions in various many-body frameworks are derived, emphasizing the relationship and properties of the different formalisms. Numerical results for specific models are presented, analyzing the evolution of the vertex at different temperatures and interactions in Matsubara and Keldysh formalisms.
Article
Astronomy & Astrophysics
W. Detmold, D. J. Murphy, A. Pochinsky, M. J. Savage, P. E. Shanahan, M. L. Wagman
Summary: The propagator sparsening algorithm reduces computational cost by constructing correlation functions from sparsened propagators defined on a coarsened lattice geometry. When studying the low-energy QCD ground-state spectrum, the extracted ground state masses and binding energies are consistent when determined from correlation functions constructed from sparsened and full propagators.
Article
Astronomy & Astrophysics
Peter Lowdon, Ralf-Arno Tripolt
Summary: In this work, we analyze the connection between real-time observables and Euclidean thermal correlation functions using a local quantum field theory approach. We demonstrate that in-medium effects can be directly extracted from the spatial momentum dependence of the Euclidean propagators, using data generated from the functional renormalization group in the quark-meson model.
Article
Astronomy & Astrophysics
Yatharth Gandhi, Sachin Jain, Renjan Rajan John
Summary: In this study, a novel relation between the parity-even and -odd parts of a correlator is used to demonstrate that the three-point function of conserved or weakly broken currents in three-dimensional conformal field theory can be obtained from either the free fermion theory or the free boson theory. In the case of large N Chern-Simons matter theories, the correlator is expressed in terms of a coupling constant dependent anyonic phase factor, which is consistent with strong-weak duality. By varying the coupling constant, the CFT correlator nicely interpolates between the correlators in the free fermion theory and the free boson theory.
Article
Optics
Hongxiang Chen, Max Nusspickel, Jules Tilly, George H. Booth
Summary: This research demonstrates how to use the variational quantum eigensolver (VQE) algorithm to calculate the dynamic correlation function of quantum systems and describe their linear response characteristics, which can converge on the frequency axis. The method is not affected by gate depth and can be used to compute correlated systems with frequency dynamics.
Article
Astronomy & Astrophysics
Lado Samushia, Zachary Slepian, Francisco Villaescusa-Navarro
Summary: This study explores the use of galaxy N-point correlation functions as standard rulers for distance-redshift relationship constraints, demonstrating that reconstruction of the initial density field can offer better constraints than analyzing higher order correlation functions of the non-linear field. Using joint analysis of two and three-point correlation functions can sometimes provide better constraints than those obtained from the initial power spectrum.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Daniel J. Farrow, Ariel G. Sanchez, Robin Ciardullo, Erin Mentuch Cooper, Dustin Davis, Maximilian Fabricius, Eric Gawiser, Henry S. Grasshorn Gebhardt, Karl Gebhardt, Gary J. Hill, Donghui Jeong, Eiichiro Komatsu, Martin Landriau, Chenxu Liu, Shun Saito, Jan Snigula, Isak G. B. Wold
Summary: Constructing catalogues of a particular type of galaxy can be complex due to interlopers contaminating the sample, especially in spectroscopic galaxy surveys. This study presents a practical method to handle redshift-dependent contaminants and projected clustering, providing unbiased clustering measurements with high contamination fractions. Additionally, a method for fitting for the redshift-dependent interloper fraction using the LAE-[O II] galaxy cross-correlation function is proposed, offering less biased results compared to assuming a single interloper fraction for the entire sample.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Multidisciplinary Sciences
Wei Chen
Summary: In this study, Taylor correlation functions are derived by hypothesizing turbulence as a phenomenon of superfluids at resonance. The longitudinal and lateral turbulent velocities in isotropic turbulent flows are obtained based on recent research on heat transfer at the speed of sound. The correlation functions are analytically determined from the velocity profiles, and amplitude and frequency factors are introduced through curve-fitting with experimental data.
SCIENTIFIC REPORTS
(2023)
Article
Physics, Multidisciplinary
Matteo Carrega, Joonho Kim, Dario Rosa
Summary: In this study, a non-equilibrium dynamics induced by strongly correlated Hamiltonians with all-to-all interactions is explored through a Sachdev-Ye-Kitaev (SYK)-based quench protocol. It is shown that the time evolution of simple spin-spin correlation functions is sensitive to the degree of k-locality of the corresponding operators, providing a tool to distinguish between operator-hopping and operator growth dynamics, which are indicative of quantum chaos in many-body quantum systems. This observation could be utilized as a promising method to probe chaotic behavior in advanced quench setups.
Article
Geochemistry & Geophysics
Xiaotao Yang, Jared Bryan, Kurama Okubo, Chengxin Jiang, Timothy Clements, Marine A. Denolle
Summary: This study systematically evaluates and compares the performance of eight stacking methods for analysing ambient seismic noise. It provides a practical guide for choosing the optimal stacking method for specific research applications in ambient noise seismology.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Physics, Multidisciplinary
A. -M Visuri, T. Giamarchi, C. Kollath
Summary: This paper studies particle transport through a chain of coupled sites connected to free-fermion reservoirs at both ends, with a local particle loss. The conductance and particle density in the steady state are calculated using the Keldysh formalism for open quantum systems. In addition to a reduction in conductance, it is found that transport can remain (almost) unaffected by the loss for certain values of the chemical potential in the lattice. It is shown that this protected transport is a result of the spatial symmetry of single-particle eigenstates. At a finite voltage, the density profile develops a drop at the lossy site, connected to the onset of nonballistic transport.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Shintaro Takayoshi, Thierry Giamarchi
Summary: We study the transport properties of a one-dimensional quantum system with disorder and compute the frequency dependence of its conductivity using numerical methods. The results show that the conductivity decays as a power law at high frequencies and follows a linear behavior at low frequencies, with both behaviors being affected by the interaction strength. The localization length also exhibits a power law dependence on the disorder strength, in agreement with theoretical predictions. These findings have implications for experiments with cold atomic gases.
EUROPEAN PHYSICAL JOURNAL D
(2022)
Article
Physics, Multidisciplinary
Paola Ruggiero, Pasquale Calabrese, Thierry Giamarchi, Laura Foini
Summary: This article studies the correlation functions after a quantum quench of a gaussian field problem, providing a fully analytical solution using the electrostatic analogy and charge images method. This analytical solution allows for obtaining all correlation functions in imaginary time, recovering and generalizing the results in real time.
Article
Physics, Multidisciplinary
Meng-Zi Huang, Jeffrey Mohan, Anne -Maria Visuri, Philipp Fabritius, Mohsen Talebi, Simon Wili, Shun Uchino, Thierry Giamarchi, Tilman Esslinger
Summary: We measure the superfluid transport of strongly interacting fermionic lithium atoms through a quantum point contact by utilizing local, spin-dependent particle loss. We find that the characteristic non-Ohmic superfluid transport, enabled by high-order multiple Andreev reflections, transitions into an excess Ohmic current when the dissipation strength exceeds the superfluid gap. Our developed model, which includes mean-field reservoirs connected to a dissipative site via tunneling, reproduces the observed nonequilibrium particle current in the Keldysh formalism, but it does not fully explain the observed loss rate or spin current.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Hugo Cayla, Pietro Massignan, Thierry Giamarchi, Alain Aspect, Christoph I. Westbrook, David Clement
Summary: We measured the momentum density in a Bose-Einstein condensate (BEC) with dilute spin impurities and observed algebraic tails decaying as 1/k4 at large momentum k, which originated from impurity-BEC interactions. The amplitudes of these tails exceeded those expected from two-body contact interactions at equilibrium in the trap. These unexpected algebraic tails were found to originate from the nontrivial dynamics of the expansion in the presence of impurity-bath interactions.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Gunnar Bollmark, Thomas Kohler, Lorenzo Pizzino, Yiqi Yang, Johannes S. Hofmann, Hao Shi, Shiwei Zhang, Thierry Giamarchi, Adrian Kantian
Summary: Correlated electron states are crucial for understanding unconventional superconductivity. However, calculating their properties accurately remains a challenge. In this work, we propose a framework combining matrix product states (MPS) with mean field (MF) to compute the properties of quasi-one-dimensional (Q1D) systems. We demonstrate the effectiveness of this framework by calculating the critical temperature for superconductivity in Q1D fermions. This approach allows for the quantitative study of correlated phases and the treatment of competing macroscopic orders.
Article
Multidisciplinary Sciences
T. -W. Zhou, G. Cappellini, D. Tusi, L. Franchi, J. Parravicini, C. Repellin, S. Greschner, M. Inguscio, T. Giamarchi, M. Filippone, J. Catani, L. Fallani
Summary: The Hall effect, which describes the motion of charged particles in magnetic fields, has important implications for material properties. Understanding this effect in interacting systems is challenging, even for small magnetic fields. In this study, we used an atomic quantum simulator to investigate the behavior of ultracold fermions in the presence of artificial magnetic fields. Through experimental measurements, we observed a universal behavior of the Hall response, which is independent of the strength of atomic interactions. This research demonstrates the capability of quantum simulation to describe strongly correlated topological states of matter.
Article
Materials Science, Multidisciplinary
Tony Jin, Paola Ruggiero, Thierry Giamarchi
Summary: We derive the bosonization of the interacting fermionic Su-Schrieffer-Heeger (SSH) model with open boundaries and use it to quantitatively describe the edge modes of the system. Our results show excellent agreement with numerical simulations, particularly in terms of the localization of the zero-energy edge mode near the boundaries. Interestingly, we find that the effects of repulsive or attractive interactions on the edge mode localization depend on the staggering parameter. We provide quantitative predictions of these effects on the localization length of the edge mode and suggest that bosonization can be generalized to other models.
Article
Materials Science, Multidisciplinary
Saptarshi Majumdar, Laura Foini, Thierry Giamarchi, Alberto Rosso
Summary: We study an XXZ spin chain coupled to an ohmic bath of harmonic oscillators at zero temperature. Two phases, separated by a Kosterlitz-Thouless transition, are found: a Luttinger liquid phase with finite spin stiffness at low coupling and a dissipative phase with vanishing spin stiffness at high coupling. The transport properties are also affected, with the Luttinger liquid phase being a perfect conductor and the dissipative phase showing finite resistivity. The effect of the bath can be interpreted as annealed disorder-inducing signatures of localization.
Article
Physics, Multidisciplinary
A. -M. Visuri, T. Giamarchi, C. Kollath
Summary: This paper investigates particle transport, particle loss, and nonequilibrium steady states in a dissipative one-dimensional lattice connected to reservoirs at both ends. By applying local particle loss to the center site, particle transport is generated between free-fermion reservoirs with different chemical potentials. The conserved current and loss current as functions of voltage in the nonlinear regime are computed using a Keldysh description. The behaviors of the currents are affected differently by the local loss, resulting in either smoothed, nearly unaffected, or even enhanced steps depending on the spatial symmetry of the single-particle eigenstate.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Physics, Multidisciplinary
Tony Jin, Joao Ferreira, Michel Bauer, Michele Filippone, Thierry Giamarchi
Summary: We have developed a semiclassical model to study the transport properties of low-dimensional fermionic lattices under the influence of external quantum stochastic noise. These systems exhibit behavior similar to quantum stochastic resistors, where bulk particle transport is diffusive and follows Ohm's/Fick's law. By extending previous studies beyond one-dimensional systems to ladder geometries, we have explored different dephasing mechanisms relevant to various physical systems. Our results show that the semiclassical description provides a useful and simpler interpretation of the conductance dependence on chemical potential, which agrees well with exact numerical solutions. Additionally, we have found that the coherence of the dephasing process in the transverse direction does not affect the conductance of quantum ladders, despite different stationary states being reached.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Physics, Multidisciplinary
Catalin-Mihai Halati, Thierry Giamarchi
Summary: We investigate the properties of interacting bosonic particles on a two-leg triangular ladder with an artificial gauge field. By using numerical simulations and analytical bosonization calculations, we explore the complex phase diagram of this system. The interplay between the frustration from the triangular lattice geometry and the interactions leads to the emergence of multiple chiral quantum phases. Phase transitions from superfluid to Mott-insulating states occur, exhibiting Meissner or vortex characteristics. Moreover, we discover a biased chiral superfluid state that breaks the symmetry between the two legs of the ladder, particularly for flux values close to pi. In the regime of hard-core bosons, we demonstrate the extension of the bond order insulator, beyond the fully frustrated ladder case, with Meissner-type chiral currents. We discuss the implications of our findings for experimental studies in cold atomic systems.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Izabella Lovas, Robert Citro, Eugene Demler, Thierry Giamarchi, Michael Knap, Edmond Orignac
Summary: We study a quantum many-body variant of the parametric oscillator using a semiclassical truncated Wigner approximation (TWA) to investigate the driven sine-Gordon model with a modulated tunnel coupling. By comparing different methods, we find that TWA can be used to explore the mode-resolved energy density dynamics and higher-order correlations between modes in the prethermal heating regime.
Article
Physics, Fluids & Plasmas
Nirvana Caballero, Thierry Giamarchi, Vivien Lecomte, Elisabeth Agoritsas
Summary: In this study, we numerically compute the roughness of a one-dimensional elastic interface and find a power-law behavior at short lengthscales. Contrary to available analytic predictions, we find that the associated exponent is less than 1. We discuss the implications of these findings for the temperature dependence of roughness and the connection with the asymptotic random-manifold regime at large lengthscales.
Article
Physics, Multidisciplinary
Tony Jin, Joao S. Ferreira, Michele Filippone, Thierry Giamarchi
Summary: We study the transport properties of generic out-of-equilibrium quantum systems connected to fermionic reservoirs. We develop a perturbation scheme in the inverse system size, named 1/N expansion, to study a large class of out of equilibrium diffusive/ohmic systems. The exact solution for quantum stochastic Hamiltonians (QSHs) models confirms the validity of our system size expansion ansatz, and its efficiency in capturing the transport properties. We consider three fermionic models: a model with local dephasing, the quantum simple symmetric exclusion process model, and a model with long-range stochastic hopping.
PHYSICAL REVIEW RESEARCH
(2022)
