Article
Physics, Multidisciplinary
Ivan P. Christov
Summary: This study compares the effects of spatial nonlocality and nonlocal causality on two entangled electrons. It finds that spatial entanglement can be accurately predicted using the TDQMC method, while nonlocal causality only leads to small oscillations in the observed electron trajectories.
Article
Chemistry, Physical
Jonas Feldt, Antoine Bienvenu, Roland Assaraf
Summary: In this paper, a new estimator in the variational Monte Carlo framework is proposed, which utilizes numerically cheap single-core subsamplings to improve the estimation of molecular properties. Furthermore, a spin-dependent core definition is introduced to simplify the algorithm and enhance its efficiency.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Computer Science, Artificial Intelligence
Souad Chennaf, Jaleleddine Ben Amor
Summary: This paper proposes a new type of entropy called Renyi entropy as an extension of logarithm entropy in an uncertain random environment and applies it to portfolio selection. The mathematical properties of Renyi entropy and partial Renyi entropy are examined and an approach for calculating partial Renyi entropy through Monte Carlo simulation is provided. The concept of Renyi cross-entropy and partial Renyi cross-entropy is introduced for uncertain random variables. Numerical examples are used to illustrate the application of partial Renyi entropy in portfolio selection.
Article
Chemistry, Physical
Tina N. Mihm, William Z. Van Benschoten, James J. Shepherd
Summary: A new approach using low-cost calculations was developed to find a twist angle that matches the coupled cluster doubles energy in a finite unit cell. The method was shown to have comparable accuracy with exact methods beyond coupled cluster doubles theory. Additionally, for small system sizes, the same twist angle can be found by comparing energies directly, suggesting a potential route towards twist angle selection.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Physics, Multidisciplinary
Ivan P. Christov
Summary: This study quantifies the quantum entanglement entropy of electrons in a one-dimensional hydrogen molecule using an appropriate partitioning of the two-dimensional configuration space. The results show that both global and local entanglement entropy increase monotonically with increasing inter-nuclear distance, while the local entropy remains peaked in the middle between the nuclei with decreasing width. The study suggests that the entropy and the energy measures have different sensitivity to the interaction between the electrons involved, possibly due to the quantum entropy calculation not explicitly accounting for the distance between nuclei.
Article
Physics, Multidisciplinary
Ivan P. Christov
Summary: The time-dependent quantum Monte Carlo method is used to calculate the entanglement of electrons in one-dimensional quantum dots with various spin configurations. The study finds that the spatial entanglement differs in parallel-spin and spin-compensated cases, with outermost opposite-spin electrons behaving like bosons in the latter case. The results are consistent with numerically exact results where comparison is possible.
Article
Astronomy & Astrophysics
Yizhuang Liu, Maciej A. Nowak, Ismail Zahed
Summary: This article derives a general formula for the replica partition function in the vacuum state for a large class of interacting theories with fermions, and uses it to analyze the spatial entanglement of interacting Dirac fermions in two-dimensional QCD. Attention is paid to the issues of infrared cutoff dependence and gauge invariance. The Renyi entropy is calculated for a single interval using the rainbow dressed quark propagator and the contributions to order Oo1) are shown to come from the off-diagonal and off mass-shell mesonic T-matrix, with no contribution to the central charge. The construction is further extended to mesonic states on the light front and shown to probe the moments of the partonic PDFs for large light-front separations. The spatial entanglement entropy following from the Renyi entropy is found to be consistent with the Ryu-Takayanagi geometrical entropy using a soft-wall AdS3 model of two-dimensional QCD in vacuum and for small and large intervals.
Article
Multidisciplinary Sciences
Hsuan-Hao Lu, Karthik Myilswamy, Ryan S. Bennink, Suparna Seshadri, Mohammed S. Alshaykh, Junqiu Liu, Tobias J. Kippenberg, Daniel E. Leaird, Andrew M. Weiner, Joseph M. Lukens
Summary: With the development of integrated biphoton frequency combs, quantum information processing in the frequency domain has attracted more attention in recent years. To address the scalability issue of frequency mixing operations, the authors propose a novel solution that utilizes pulse shapers and electro-optic phase modulators to perform random operations. They successfully verify the entanglement and reconstruct the full density matrix of biphoton frequency combs, achieving the highest dimension for frequency bins to date. The employed Bayesian statistical model can be tailored to various quantum systems with restricted measurement capabilities, providing an opportunistic tomographic framework.
NATURE COMMUNICATIONS
(2022)
Article
Optics
Zhenhuan Liu, Pei Zeng, You Zhou, Mile Gu
Summary: This article introduces a more experimentally accessible quantifier of total correlations, which can be estimated using only single-qubit measurements, without the need for complex state tomography and coherent interference of multiple copies of a given state.
Article
Chemistry, Physical
Giovani L. Rech, Andre L. Martinotto, Janete E. Zorzi, Claudio A. Perottoni
Summary: The relative stability between the crystal structure of alpha-F-2, space group C2/c, and a hypothesized high-pressure phase, space group Cmce, was investigated using Density Functional Theory and Quantum Monte Carlo calculations. The analysis of the phonon dispersion spectra showed that the Cmce phase exhibits dynamical instability near the Gamma-point at ambient pressure, which disappears under increasing pressure. This instability is attributed to the absence of sigma-holes in the fluorine molecule, resulting in repulsive head-to-head interactions between molecules.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Oliver A. Bramley, Timothy J. H. Hele, Dmitrii Shalashilin
Summary: Zombie states are a formalism that describes coupled coherent fermionic states in a computationally tractable manner. This study extends the previous work on Zombie states and develops efficient algorithms for evaluating operators and addressing normalization. It also presents techniques for improving accuracy and calculating low-lying excited states.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Salvatore Francesco Emanuele Oliviero, Lorenzo Leone, You Zhou, Alioscia Hamma
Summary: In this work, the robustness of a form of topological entanglement under a model of random local perturbations is analytically proven. The concept of topological purity is defined, and it is shown that, in the context of quantum double models, this quantity can detect topological order and remains stable under the action of a random shallow quantum circuit.
Article
Physics, Multidisciplinary
Marcin Plodzien, Maciej Lewenstein, Emilia Witkowska, Jan Chwedenczuk
Summary: We demonstrate that one-axis twisting (OAT) is a powerful source of many-body Bell correlations for creating nonclassical states of bosonic qubits. We develop an analytical and universal treatment that allows us to identify the critical time for the emergence of Bell correlations and predict their depth at subsequent times. Our findings are illustrated using a highly nontrivial example of OAT dynamics generated with the Bose-Hubbard model.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Fluids & Plasmas
Tanmoy Biswas, A. de Oliveira Junior, Michal Horodecki, Kamil Korzekwa
Summary: This paper derives a version of the fluctuation-dissipation theorem within a resource-theoretic framework, providing a connection between the response of a system subject to perturbation and the fluctuations associated with observables in equilibrium. The results enable the optimal performance analysis of thermodynamic protocols for quantum states with coherence between different energy eigenstates.
Article
Physics, Fluids & Plasmas
Nathan S. Nichols, Paul Sokol, Adrian Del Maestro
Summary: This paper presents a parameter-free evolutionary algorithm for analytic continuation to generate the dynamic structure factor from imaginary time correlation functions, achieving enhanced spectral fidelity and reduced CPU hours without the need for fine-tuning of algorithmic control parameters.
Article
Physics, Particles & Fields
Fabien Alet, Masanori Hanada, Antal Jevicki, Cheng Peng
Summary: We study the general properties of coupled quantum systems, focusing on SYK models and Pauli spin chains with random magnetic fields. Numerical computations in the coupled SYK model are pushed to the thermodynamic limit, showing good agreement with analytical results in the large-q limit. The understanding of confinement/deconfinement transition mechanisms enables precise estimation of quantum entanglement, supporting the dual gravity interpretation linking deconfinement to the disappearance of wormholes.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Multidisciplinary
Didier Poilblanc, Matthieu Mambrini, Fabien Alet
Summary: The (positive) thermal density operator in the tensor network framework can be approximated by a double layer of infinite iPEPO coupled via ancilla degrees of freedom. A variational optimization is performed on plaquettes to investigate the thermal properties of the spin1/2 Heisenberg model, showing accurate behavior of various observables and validating the imaginary-time evolution procedure. The method is extended to frustrated models, with preliminary results shown.
Article
Physics, Multidisciplinary
Francesca Pietracaprina, Fabien Alet
Summary: The study suggests the presence of a many-body localization transition in a disordered quantum dimer model on the honeycomb lattice, with conclusions drawn through numerical methods. The results indicate the existence of localization transition within the scale of the system.
Article
Physics, Multidisciplinary
Francesca Pietracaprina, Nicolas Laflorencie
Summary: Investigating many-body localization is challenging due to the exponential growth of the Hilbert space, but a new method has been developed to efficiently discard irrelevant parts and access larger systems at strong disorder, leading to a quantitative prediction of the MBL transition with a geometric interpretation of the multifractality of the Hilbert space.
Article
Physics, Multidisciplinary
M. Dupont, Y. O. Kvashnin, M. Shiranzaei, J. Fransson, N. Laflorencie, A. Kantian
Summary: Monolayer CrCl3 has the unique advantage of tunable magnetic anisotropy under compressive strain, allowing for the production and study of various phases of 2D magnetism. This material shows potential in achieving high BKT transition temperatures due to its weak easy-plane anisotropy.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Olivier Giraud, Nicolas Mace, Eric Vernier, Fabien Alet
Summary: This study extends the gap ratio distribution analysis to cases with discrete symmetries, deriving analytical surmises for random matrices with multiple independent blocks and validating them through simulations. The research shows how the study of spectral gap ratios can reveal the presence of symmetries in various models in many-body physics.
Article
Materials Science, Multidisciplinary
Bhupen Dabholkar, G. J. Sreejith, Fabien Alet
Summary: We investigated the finite-temperature phase diagram of the quantum dimer model on the square lattice using quantum Monte Carlo method. A high-temperature critical phase with power-law correlations was found, extending down to the Rokhsar-Kivelson point, where a reentrance effect was observed in the lines of constant exponent. Finite-temperature transitions to ordered states (columnar and staggered) were also found for small values of the kinetic energy strength, matching those of interacting classical dimer models.
Article
Physics, Multidisciplinary
Robin Schaefer, Jan C. Budich, David J. Luitz
Summary: Investigated the influence of symmetry preserving interaction between fermions on exceptional points. Found that exceptional points are stable in the presence of the interaction and form characteristic exceptional fans. Additionally, the interaction can also create new exceptional points.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Imre Hagymasi, Robin Schaefer, Roderich Moessner, David J. Luitz
Summary: This study focuses on the investigation of the pyrochlore Heisenberg antiferromagnet in a magnetic field, revealing interesting magnetic behaviors such as a finite triplet gap and a stable 1/2 magnetization plateau.
Article
Materials Science, Multidisciplinary
S. Allenspach, A. Madsen, A. Biffin, M. Bartkowiak, O. Prokhnenko, A. Gazizulina, X. Liu, R. Wahle, S. Gerischer, S. Kempfer, P. Heller, P. Smeibidl, A. Mira, N. Laflorencie, F. Mila, B. Normand, Ch. Rueegg
Summary: Researchers used the HFM/EXED instrument to investigate the properties of BaCuSi2O6 at a magnetic field of 25.9 T, revealing the nature of its magnetic ordered phase and its significance in studying quasi-2D physics arising from layered structures and different bilayer types.
Article
Physics, Multidisciplinary
Nicolas Laflorencie, Gabriel Lemarie, Nicolas Mace
Summary: By numerically exploring Z2-symmetric random interacting Ising-Majorana chains at high energy, we have discovered a very rich phase diagram with a much broader thermal phase separating two topologically distinct many-body localization (MBL) regimes than previously known. Additionally, we have found that MBL spin-glass order is always associated with many-body spectral pairing, potentially indicating the presence of a strong zero mode operator, opening up fascinating prospects for MBL-protected topological qubits.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Jimin L. Li, Dominic C. Rose, Juan P. Garrahan, David J. Luitz
Summary: This study investigates the effects of strong dissipation in quantum systems with a notion of locality, revealing the emergence of a manifold of metastable states due to variations in the dissipation strength. The findings are confirmed through a perturbative treatment using a simple model involving good and bad qubits with reduced dissipation.
Article
Materials Science, Multidisciplinary
Pranay Patil, Fabien Alet, Sylvain Capponi, Matthieu Mambrini
Summary: We consider a model Hamiltonian with two SU(4) fermions per site on a square lattice, showing a competition between bilinear and biquadratic interactions. Using a basis transformation, we show that part of the phase diagram can be simulated with quantum Monte Carlo simulations without a sign problem. Evidence for spin nematic and valence-bond crystalline phases is found, with a weak first-order phase transition separating them. An emergent U(1) symmetry is observed in the valence-bond crystal histograms, suggesting proximity to a deconfined quantum critical point. Our results are obtained using a loop algorithm that allows large-scale simulations of bilinear-biquadratic SO(N) models on arbitrary lattices in a certain parameter regime.
Article
Physics, Multidisciplinary
Stephan Allenspach, Pascal Puphal, Joosep Link, Ivo Heinmaa, Ekaterina Pomjakushina, Cornelius Krellner, Jakob Lass, Gregory S. Tucker, Christof Niedermayer, Shusaku Imajo, Yoshimitsu Kohama, Koichi Kindo, Steffen Kramer, Mladen Horvatic, Marcelo Jaime, Alexander Madsen, Antonietta Mira, Nicolas Laflorencie, Frederic Mila, Bruce Normand, Christian Ruegg, Raivo Stern, Franziska Weickert
Summary: Classical and quantum phase transitions are studied, demonstrating that observable 3D quantum critical scaling is restored by the structural simplification arising from light Sr substitution in Han purple through experiments and simulations.
PHYSICAL REVIEW RESEARCH
(2021)
Article
Materials Science, Multidisciplinary
Maxime Dupont, Nicolas Laflorencie
Summary: Quantum spins on small-world networks exhibit unique behaviors compared to classical systems, with two distinct power-law behaviors for T-c versus the average strength of the extra couplings. This is influenced by a competition between characteristic length scales of the random graph and the thermal correlation length of the underlying 1D system, challenging mean-field theories. The study also explores the fate of a gapped 1D spin chain against the small-world effect.
