Article
Physics, Fluids & Plasmas
Peter Gurin, Szabolcs Varga
Summary: We studied a two-state model of attractive hard rods and found that at low densities, particles form long chains parallel to each other, while at high densities they form a Tonks gas. Increasing stickiness between the rods leads to a stronger structural change and a nearly horizontal pressure-density curve.
Article
Physics, Condensed Matter
Myung-Hoon Chung, Edmond Orignac, Didier Poilblanc, Sylvain Capponi
Summary: The study modified the one-dimensional Hubbard model by introducing an external pairing potential, and quantitatively determined the system's zero-temperature phase diagram using algorithms based on matrix product states and matrix product operator. By computing local quantities and entanglement, different phases were distinguished effectively.
PHYSICA B-CONDENSED MATTER
(2021)
Article
Computer Science, Interdisciplinary Applications
Hongfei Zhan, Zhenning Cai, Guanghui Hu
Summary: This paper theoretically and numerically explores the ground state Wigner function of a many-body system. An eigenvalue problem for the Wigner function is derived based on the energy operator of the system, and a numerical method is designed for solving this problem. Numerical experiments verify the method's effectiveness and demonstrate its potential application with density functional theory for large scale systems.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Optics
Tobias Ilg, Hans Peter Buechler
Summary: We study the behavior of the excitation spectrum across the quantum phase transition from a superfluid to a supersolid phase of a dipolar Bose gas in one dimension. Using an effective Hamiltonian that includes beyond-mean-field effects, we analyze the system based on Bogoliubov theory with multiple order parameters. Our results show that the supersolid phase exhibits a stable excitation spectrum with Goldstone modes and an amplitude mode in the low-energy regime, and the transition into the supersolid phase is driven by the roton instability in a parameter regime achievable for dysprosium atoms.
Article
Physics, Multidisciplinary
Adrian Huerta, Taras Bryk, Victor M. Pergamenshchik, Andrij Trokhymchuk
Summary: The study presents results of molecular dynamic studies on the collective dynamics in a system of hard disks confined to a narrow quasi-one-dimensional channel. It shows that in such a quasi-1D system, transverse excitations follow specific dispersion law typical of optical transverse modes, contrasting sharply to the cases of 1D and 2D arrays of hard disks. Other peculiarities of the dispersion of collective excitations as well as some results of disk structuring and thermodynamics of the system are also discussed.
FRONTIERS IN PHYSICS
(2021)
Article
Chemistry, Inorganic & Nuclear
Vinay Kaushik, D. Venkateshwarlu, R. Venkatesh, V Ganesan
Summary: A comprehensive study of superconducting and normal state properties of Nb2Pd(S0.9Te0.1)5 system embedded with solid chunks and fibers has been conducted. The analysis reveals bulk superconductivity in the fibers, with vortex motion in mixed state following Kramer's scaling and suggesting grain boundary pinning mechanism. The thermal activation energy indicates a weak coupling strength limit.
JOURNAL OF SOLID STATE CHEMISTRY
(2022)
Article
Physics, Fluids & Plasmas
Deepak Dhar, R. Rajesh
Summary: The study investigates the asymptotic behavior of entropy when fully covering a square lattice with rods of specific sizes in the limit of large k. The research reveals the conditions under which full coverage is possible and the basic flip moves between configurations. In the large k limit, per-site entropy tends towards a specific mathematical function.
Article
Materials Science, Multidisciplinary
Yan Xu, Hanqin Ding
Summary: The ground-state properties of a modified 1D Penson-Kolb-Hubbard model are discussed using the bosonization scheme and renormalization group analysis. The model exhibits charge-density-wave, spin-density-wave, and singlet superconductivity instabilities at quarter filling.
RESULTS IN PHYSICS
(2022)
Article
Chemistry, Physical
R. Melnyk, Y. Kalyuzhnyi, G. Kahl, A. Baumketner
Summary: In this study, the effects of molecule shape and interaction range on the critical behavior of a model fluid system are investigated. It is found that increasing molecule asphericity decreases the critical temperature, while the critical density depends on both the range of attraction and the asphericity of the molecule.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Kira Kolpatzeck, Lothar Brendel, Rolf Moeller, Roberto Robles, Nicolas Lorente
Summary: The electronic state at the interface between Ag(111) surface and NaCl island was investigated. The presence of moire patterns caused by lattice mismatch between NaCl islands and Ag(111) results in a weak periodic 1D potential for the electronic state. Although the ideal 2D system should only modulate the local electronic density below the mini band gap, scanning tunneling microscopy and spectroscopy experiments observed such modulation even in the forbidden energy range. It was found that the loss of coherence and the detection mechanism by the STM are responsible for this experimentally observed modulation, which should be suppressed in an ideal system.
Article
Chemistry, Multidisciplinary
Orion Ciftja
Summary: This paper investigates a finite system of classical electric dipoles localized at the sites of a regular one-dimensional crystal lattice and calculates the ground state energy for any number of dipoles. The expression for the ground state energy is given in terms of special functions and converges to the correct result in the limit of infinitely many dipoles. Additionally, simpler but accurate approximate expressions for the ground state energy are introduced.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2023)
Article
Chemistry, Physical
Anja Kuhnhold, Paul van der Schoot
Summary: The internal structure of nematic droplets or tactoids formed by rod-like particles in a gas of spherical ghost particles is studied using Monte Carlo simulations. The size of the droplets strongly affects their shape and internal structure. An external quadrupolar alignment field makes the director field more uniform, but does not significantly increase the aspect ratio of the droplets.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Yuya Kurebayashi, Hiroki Oshiyama, Naokazu Shibata
Summary: The study systematically calculated the ground state of the one-dimensional t-J(s)-J(tau) model using the density matrix renormalization group method and determined the ground-state phase diagram at quarter filling. Weak channel fluctuations were found to stabilize the spin-gap state, while strong channel fluctuations led to the transition to the insulator.
Article
Physics, Multidisciplinary
Maksim Tomchenko
Summary: In this study, exact solutions for a one-dimensional system of N = 2;3 spinless point bosons with zero boundary conditions are studied using Bethe ansatz. The density profile and nodal structure of the lowest states for different gamma values are obtained. The ideal crystal is found to correspond to specific quantum numbers when the coupling constant gamma is less than or equal to 1. The ground state of the system corresponds to a liquid state for any gamma and large N, and has a nodeless wave function.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2022)
Article
Materials Science, Multidisciplinary
Pratyay Ghosh
Summary: We present the exact dimer ground state of a quantum antiferromagnet defined on a quasicrystal constructed from the bronze-mean hexagonal quasicrystal. A coupling isotropy on the first- and second-neighbor bonds is sufficient to stabilize a product state of singlets on the third-neighbor bonds. We also provide a systematic approach for constructing additional crystals, quasicrystals, and amorphous structures that can sustain an exact dimer ground state.
Article
Physics, Multidisciplinary
G. Guijarro, G. E. Astrakharchik, J. Boronat
Summary: This study demonstrates the formation of ultradilute quantum liquids with ultracold bosonic dipolar atoms in a bilayer geometry. The proposed system uses dipolar interactions alone to create a self-bound state without the need for an additional short-range potential. Quantum Monte Carlo simulations reveal a diverse ground-state phase diagram with quantum phase transitions between liquid, solid, atomic gas, and molecular gas phases. The stabilization mechanism of the liquid phase involves an effective balance between dimer-dimer attraction and three-dimer repulsion, with the equilibrium density controlled by the interlayer distance.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Jordi Marti, Ferran Mazzanti, Grigori E. Astrakharchik, Lluis Batet, Laura Portos-Amill, Borja Pedreno
Summary: Fusion energy is a promising alternative for a decarbonised energy system. This study investigates the behavior of lithium-helium mixtures and introduces a new microscopic model to describe the formation of helium droplets, which could impact the performance of breeding blankets in future fusion nuclear reactors.
Article
Physics, Condensed Matter
Sergi Pradas, Jordi Boronat
Summary: The miscibility of two dipolar quantum gases at zero temperature was studied using the diffusion Monte Carlo method. The results show that the mixing between the two species is constrained by the relative dipolar moments and masses.
Article
Physics, Multidisciplinary
Giulia De Rosi, Riccardo Rota, Grigori E. Astrakharchik, Jordi Boronat
Summary: We report an intriguing anomaly in the temperature dependence of the specific heat of a one-dimensional Bose gas. This anomaly resembles a superfluid-to-normal phase transition observed in higher dimensions, despite phase transitions not being allowed in one dimension. The anomaly can be attributed to unpopulated states that act as an energy gap located below the hole branch in the excitation spectrum. Furthermore, thermal fluctuations at temperatures near the anomaly threshold can become comparable to the maximum hole energy, leading to a qualitative change in the excitation structure.
Article
Education, Scientific Disciplines
Jordi Pera, Jordi Boronat
Summary: The s-wave and p-wave scattering lengths and the s-wave effective range are the most important parameters in the study of low-energy scattering. By solving the scattering problem and deriving two useful formulas, we are able to calculate these parameters for any angular momentum, as long as the Wigner threshold law holds. We also analyze the behavior of the scattering parameters near Feshbach resonances and provide practical activities for learning scattering theory.
AMERICAN JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
Ivan Morera, Rafal Oldziejewski, Grigori E. Astrakharchik, Bruno Julia-Diaz
Summary: We propose a mechanism for liquid formation in strongly correlated lattice systems by studying dipolar bosons in one-dimensional optical lattices as an example. We present a perturbative theory and validate it through simulations for the energetic and structural properties of the system's phases. We analyze the nonequilibrium properties and calculate the dynamic structure factor.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Giulia De Rosi, Riccardo Rota, Grigori E. Astrakharchik, Jordi Boronat
Summary: In this study, the effect of thermal fluctuations on correlations in a one-dimensional Bose gas with repulsive interactions is comprehensively investigated. The pair correlation function, static structure factor, and one-body density matrix are calculated using the exact ab-initio Path Integral Monte Carlo method for various interaction strengths and temperatures. A detailed comparison with different theoretical models is provided. The Monte Carlo results agree excellently with the tractable limits and serve as an important benchmark for future experiments in different platforms.
NEW JOURNAL OF PHYSICS
(2023)
Article
Multidisciplinary Sciences
Grigory E. Astrakharchik, Luis A. Pena Ardila, Krzysztof Jachymski, Antonio Negretti
Summary: In this study, using quantum Monte Carlo methods, we investigate the static properties of two ionic impurities in a bosonic bath and identify three bipolaronic regimes. We further reveal strong bath-induced interactions between the two ionic polarons. Our findings demonstrate the necessity of numerical simulations in describing highly correlated impurity models.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Cong Liu, Ion Errea, Chi Ding, Chris Pickard, Lewis J. J. Conway, Bartomeu Monserrat, Yue-Wen Fang, Qing Lu, Jian Sun, Jordi Boronat, Claudio Cazorla
Summary: It is predicted that solid helium becomes a metal at high pressures and transitions into an excitonic insulator and a superconductor. The study reveals that helium becomes an excitonic insulator before metallization and a superconductor after metallization. These phenomena could be crucial for improving our understanding and modeling of celestial bodies.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
M. C. Gordillo, J. Boronat
Summary: The phase diagram of the second layer of para-H-2 adsorbed on graphite was calculated using quantum Monte Carlo methods. The study revealed that this nearly two-dimensional crystal exhibits a finite superfluid density at a certain total density, which can be experimentally observed.
Article
Optics
Raul Bombin, Viktor Cikojevic, Juan Sanchez-Baena, Jordi Boronat
Summary: This study focuses on the repulsive Fermi polaron in a two-component, two-dimensional system of fermionic atoms, investigating properties such as polaron energy, quasiparticle residue, and effective mass using the diffusion Monte Carlo method. The results highlight the importance of considering the effective range and scattering length to reproduce experimental results, as well as the establishment of universality through different model potentials for the interaction between the Fermi sea and the impurity. This underscores the significance of quantum fluctuations and beyond mean-field effects in accurately describing the Fermi polaron problem.
Article
Optics
Giulia De Rosi, Grigori E. Astrakharchik, Pietro Massignan
Summary: This study examines the low-temperature thermodynamics of weakly interacting uniform liquids in one-dimensional attractive Bose-Bose mixtures, using the Bogoliubov approach to describe quantum and thermal fluctuations. The research delves into two different thermal mechanisms driving the liquid-to-gas transition, computes key thermodynamic quantities of the liquid, and highlights the temperature-dependent nature of these quantities for their potential use as precise temperature probes in experiments on quantum liquids.
Article
Materials Science, Multidisciplinary
Yu E. Lozovik, I. L. Kurbakov, G. E. Astrakharchik, J. Boronat
Summary: The proposed method provides an accurate estimation of the condensate fraction in strongly correlated systems under various conditions, with experimental measurements confirming its effectiveness.
