Article
Physics, Multidisciplinary
Ettore Vitali, Peter Rosenberg, Shiwei Zhang
Summary: By leveraging cutting-edge numerical methodologies, this study investigates the ground state and properties of a two-dimensional spin-polarized Fermi gas in an optical lattice. The results provide strong evidence of the stability of the elusive Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluid phase, and show the existence of density order in the system, suggesting the possibility of an intricate coexistence of long-range orders in the ground state. The study also points out significant differences between the ground-state properties and the standard mean-field description, providing a compelling avenue for future theoretical and experimental explorations of spin imbalance, strong interactions, and superfluidity in this exotic phase of matter.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Fluids & Plasmas
Nik O. Gjonbalaj, David K. Campbell, Anatoli Polkovnikov
Summary: This article examines the application of shortcuts to adiabaticity (STAs) in classical systems. The performance of the approximate counterdiabatic (ACD) driving is numerically compared in a quartic anharmonic oscillator and the Fermi-Pasta-Ulam-Tsingou lattice. It is found that simple forms of ACD driving can significantly suppress excitations.
Article
Optics
Piotr Magierski, Bugra Tuzemen, Gabriel Wlazlowski
Summary: The motion of spin-polarized impurity in ultracold atomic gas is determined by a critical velocity, which correlates with the spin imbalance inside the impurity. The effective mass of the impurity in two dimensions is calculated, showing a scaling relationship with the impurity's surface area. The instability of impurities near a vortex is demonstrated as a significant impact of these findings.
Article
Physics, Nuclear
Isaac Vidana
Summary: The study investigates the properties of a spin-down neutron impurity in a low-density free Fermi gas of spin-up neutrons, comparing the results with quantum Monte Carlo calculations and previous studies. It is found that the impurity's energy, effective mass, and quasiparticle residue exhibit slight variations within specific ranges, resembling those of an attractive Fermi polaron in the unitary limit. The research demonstrates compatibility with results derived from ultracold atoms, indicating similar properties under certain conditions.
Article
Physics, Multidisciplinary
Bugra Tuzemen, Tomasz Zawislak, Gabriel Wlazlowski, Piotr Magierski
Summary: We investigate the properties of spin-imbalanced ultracold Fermi gas at low temperatures over a wide range of spin polarizations. We employ microscopic calculations using mean-field and density functional theory approaches without any symmetry constraints. At low polarization values, the system is predicted to consist of multiple spin-polarized droplets. As the polarization increases, the system self-organizes into disordered structures resembling liquid crystals and can energetically compete with ordered structures like grid-like domain walls. Further increasing polarization leads to the development of regularities that can be considered as supersolid, where periodic density modulation and pairing correlations coexist. The robustness of the results has been verified against temperature effects, dimensionality, and the presence of a trapping potential. Dynamical stability has also been investigated.
NEW JOURNAL OF PHYSICS
(2023)
Article
Optics
Junhyun Lee, Pavel A. Volkov, B. J. DeSalvo, J. H. Pixley
Summary: We theoretically investigate the emergent phases of strongly correlated spin-21 Fermi gases of Rydberg-dressed atoms in a one-dimensional optical lattice. At weak coupling, a bosonization description is used to demonstrate the ability to drive alternating quantum phase transitions between distinct Luttinger liquids. At strong coupling, the ground state exhibits nontrivial phase separation, with Luttinger liquid puddles separated by magnetic domain walls, due to the interplay of the incommensurate filling and the Rydberg core length scale. These phases can be detected in ultracold gases of Rydberg atoms made from 6Li.
Article
Physics, Multidisciplinary
Jia Wang, Xia-Ji Liu, Hui Hu
Summary: In this study, we investigate a heavy impurity immersed in an interacting Fermi superfluid using the exact functional determinant approach. We analyze the impact of the pairing gap on the properties of quasiparticles revealed by two spectroscopies. The results show interesting phenomena, such as dark continuum, molecule-hole continuum, and repulsive polaron, depending on the scattering conditions.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Ke-Jun Xu, Qinda Guo, Makoto Hashimoto, Zi-Xiang Li, Su-Di Chen, Junfeng He, Yu He, Cong Li, Magnus H. Berntsen, Costel R. Rotundu, Young S. Lee, Thomas P. Devereaux, Andreas Rydh, Dong-Hui Lu, Dung-Hai Lee, Oscar Tjernberg, Zhi-Xun Shen
Summary: Electron-doped cuprates exhibit strong antiferromagnetic correlations, leading to the prevalent belief that antiferromagnetic spin fluctuations mediate Cooper pairing. However, the paradox arises from the observation that the superconducting gap is maximized at locations where the normal-state low-energy spectral weight is suppressed. By studying Nd2-xCexCuO4, researchers observe Bogoliubov quasiparticles and faint Fermi surface, suggesting that antiferromagnetic spin fluctuations mediate Cooper pairing.
Article
Optics
Lukas Rammelmueller, Yaqi Hou, Joaquin E. Drut, Jens Braun
Summary: We theoretically study the pairing behavior of the unitary Fermi gas in the normal phase, with analysis based on spin susceptibility response to an external magnetic field. Our findings are discussed in context of the phase diagram of the spin-polarized unitary Fermi gas.
Article
Multidisciplinary Sciences
Nico Huber, Valentin Leeb, Andreas Bauer, Georg Benka, Johannes Knolle, Christian Pfleiderer, Marc A. Wilde
Summary: After a century of research, the low-energy excitations in metals, which have been explained well by effective single-particle theories, now raise questions about spectroscopic signatures beyond single-particle, single-band behavior. This study identifies quantum oscillations in the topological semimetal CoSi that deviate from standard descriptions in two fundamental aspects. The findings are in agreement with generic model calculations and can help identify and measure correlation phenomena in various materials.
Article
Physics, Multidisciplinary
B. Stoddart-Stones, X. Montiel, M. G. Blamire, J. W. A. Robinson
Summary: Superconducting spintronics aims to enhance the performance of spintronics-based devices by utilizing the interaction between magnetic order and superconductivity. In this study, the authors experimentally investigate a superconducting spin valve and observe a crossover from giant magnetoresistance to the superconducting spin-valve effect as the thickness of the material changes.
COMMUNICATIONS PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
M. Mezidi, A. Alekhin, G. D. Gu, D. Colson, S. Houver, M. Cazayous, Y. Gallais, A. Sacuto
Summary: This study tracked the transition from an antiferromagnetic Mott insulator to a superconducting metal in the Bi-2212 cuprate using electronic Raman scattering spectroscopy. The features of the pseudogap phase developing during this transition were interpreted as the blocking of charge carriers by enhanced AFM correlations. The relation between the superconducting gap and transition temperature with AFM correlations suggests their key role in the mechanism of superconductivity.
Article
Physics, Multidisciplinary
Senne Van Loon, Jacques Tempere, Hadrien Kurkjian
Summary: This study investigates the fermionic quasiparticle spectrum in a zero-temperature superfluid Fermi gas and how it is affected by different disintegration processes. In addition to the disintegration by emission of a collective boson, the study also considers disintegration events where three quasiparticles are emitted. It is found that both disintegration processes are described by a t-matrix self-energy and that the quasiparticle spectrum is heavily distorted near the 1 -> 3 disintegration threshold at strong coupling.
Article
Materials Science, Multidisciplinary
Ruipeng Li, Jonas von Milczewski, Atac Imamoglu, Rafal Oldziejewski, Richard Schmidt
Summary: We study induced pairing between two identical fermions mediated by an attractively interacting quantum impurity in two-dimensional systems. Based on a stochastic variational method (SVM), we investigate the influence of confinement and finite interaction range on the ground state of the quantum three-body problem. We find that confinement and a finite interaction range can enhance trimer stability and overcome Coulomb repulsion, opening possibilities for electron pairing beyond conventional paradigms.
Article
Astronomy & Astrophysics
Bhubanjyoti Bhattacharya, Suman Kumbhakar, David London, Nicolas Payot
Summary: We introduced U-spin symmetry [SU(2)Uspin] to the Hamiltonian of B decays and found equal amplitudes related by the exchange dε>s. We also observed U-spin triangle relations among amplitudes for specific processes. Fit results showed that 100% U-spin breaking is required, suggesting the presence of new physics.
Article
Physics, Multidisciplinary
R. Cominotti, A. Berti, A. Farolfi, A. Zenesini, G. Lamporesi, I. Carusotto, A. Recati, G. Ferrari
Summary: We experimentally measured the dispersion relation of density and spin collective excitation modes in an elongated two-component superfluid of ultracold bosonic atoms. By utilizing a parametric spectroscopic technique based on external modulation of the transverse confinement frequency, we observed the formation of density and spin Faraday waves. Furthermore, we demonstrated that coherent coupling between the two components breaks the phase symmetry and imparts a finite mass to the spin modes.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Francesco Di Colandrea, Amin Babazadeh, Alexandre Dauphin, Pietro Massignan, Lorenzo Marrucci, Filippo Cardano
Summary: In this work, a method of photonic quantum walks using liquid-crystal meta-surfaces is reported, enabling ultra-long distance walks between hundreds of optical modes. By exploiting spin-orbit effects, this method allows for space-dependent polarization transformations and mixing of circularly polarized optical modes with quantized transverse momentum. By using only a few meta-surfaces, quantum walks up to 320 discrete steps are simulated without optical amplification, surpassing current state-of-the-art experiments. Rating: 9 points.
Article
Physics, Multidisciplinary
S. Bresolin, A. Roy, G. Ferrari, A. Recati, N. Pavloff
Summary: Close to the demixing transition, the degree of freedom associated with relative density fluctuations of a two-component Bose-Einstein condensate is described by a nondissipative Landau-Lifshitz equation. In the quasi-one-dimensional weakly immiscible case, this mapping surprisingly predicts that a dark-bright soliton should oscillate when subject to a constant force favoring separation of the two components. We propose a realistic experimental implementation of this phenomenon which we interpret as a spin -Josephson effect in the presence of a movable barrier.
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
V. E. Colussi, F. Caleffi, C. Menotti, A. Recati
Summary: In this study, the physics of a mobile impurity confined in a two-dimensional lattice and interacting with a Bose-Hubbard bath is investigated at zero temperature. By employing the quantum Gutzwiller formalism, a beyond-Frohlich model of the bath-impurity interaction is developed to understand the properties of the polaronic quasiparticle formed by dressing the impurity with quantum fluctuations of the bath. It is found that a stable and well-defined polaron exists in the entire phase diagram of the bath, except for the low tunneling limit of the hard-core superfluid. The properties of the polaron are highly sensitive to different universality classes of the quantum phase transition between the superfluid and Mott insulating phases, serving as a definitive probe of correlations and collective modes in a quantum critical many-body environment.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
R. Cominotti, A. Berti, C. Dulin, C. Rogora, G. Lamporesi, I. Carusotto, A. Recati, A. Zenesini, G. Ferrari
Summary: This study demonstrates a quantum phase transition from a paramagnetic to a ferromagnetic state in an extended atomic superfluid with a coherent coupling between two internal states. The nature of the transition is experimentally assessed using phase diagrams, hysteresis phenomena, magnetic susceptibility, and magnetization fluctuations. The observed features are found to be consistent with mean-field calculations, and experimental protocols are developed to generate domain walls in the ferromagnetic state.
Article
Physics, Multidisciplinary
Matteo Caldara, Andrea Richaud, Massimo Capone, Pietro Massignan
Summary: We have studied a superfluid in a planar annulus with vortices having massive cores. The analytical point-vortex model reveals that these massive vortices can have radial oscillations on top of their uniform precession. However, when the vortex mass exceeds a critical value, the oscillatory motion becomes unstable and the vortices are driven towards the edges of the annulus. By considering an analogy with the motion of a charged particle in a static electromagnetic field, we have developed a plasma orbit theory that accurately describes the trajectories even beyond the regime of small radial oscillations. These findings are supported by numerical solutions of coupled two-component Gross-Pitaevskii equations. We have also extended the analysis to a necklace of vortices symmetrically arranged within the annulus.
Review
Physics, Applied
Alessio Recati, Sandro Stringari
Summary: Supersolidity is an intriguing state of matter that combines superfluid and crystal features. It has been observed in atomic gases, where density modulations, coherence effects, and new Goldstone modes have been observed. Future research will focus on issues such as the realization of quantized vortices, the role of dimensionality, and the nature of phase transitions.
NATURE REVIEWS PHYSICS
(2023)
Article
Optics
Andrea Richaud, Giacomo Lamporesi, Massimo Capone, Alessio Recati
Summary: Quantum vortices with effective inertial mass, introduced by massive particles in their cores, exhibit new phenomena beyond the standard picture of massless superfluid vortex dynamics. In this study, we propose a scheme to generate controllable and repeatable collisional events between massive vortices. We demonstrate two mass-driven fundamental processes: the annihilation of two counter-rotating vortices and the merging of two co-rotating vortices. This reveals new mechanisms for incompressible-to-compressible kinetic-energy conversion and the stabilization of doubly quantized vortices in flat superfluids.
Article
Optics
Arko Roy, Miki Ota, Franco Dalfovo, Alessio Recati
Summary: This study investigates the fate of a paramagnetic-ferromagnetic quantum phase transition in a two-dimensional coherently coupled Bose mixture of dilute ultracold atomic gases at finite temperature. Numerical simulations using the stochastic Gross-Pitaevskii formalism reveal a finite-temperature critical line for the transition by extracting the average magnetization, magnetic fluctuations, and characteristic relaxation frequency. The critical point shows a linear shift with temperature and the quantities used to probe the transition exhibit temperature power-law scaling. The critical slowing down is well approximated by the square of the spin excitation gap at zero temperature.
Article
Optics
Andrea Richaud, Pietro Massignan, Vittorio Penna, Alexander L. Fetter
Summary: We study the motion of a superfluid vortex in condensates with different background density profiles and propose an effective point-vortex model. Both empty-core and filled-core vortices are analyzed, and it is found that the presence of a core leads to the vortex acquiring mass. The dynamics of the vortex with the localized massive core is influenced by the energy dependence on the radial position and the trap potential.
Article
Optics
Nikolay Yegovtsev, Pietro Massignan, Victor Gurarie
Summary: This paper examines strong boson-impurity interactions with finite range in a Bose gas. It shows that for attractive impurity-boson interactions, including the unitary point, static properties of a Bose polaron in a dilute Bose gas can be calculated using the scattering length and an additional parameter characterizing the range of the interactions.
Review
Physics, Atomic, Molecular & Chemical
Francesco Scazza, Matteo Zaccanti, Pietro Massignan, Meera M. Parish, Jesper Levinsen
Summary: This article provides an overview of the current theoretical and experimental understanding of the properties of repulsive polarons, which are quasiparticles formed by coupling a mobile impurity to the elementary excitations of a many-particle background. The study of these quasiparticles is important for understanding various quantum many-body systems in ultracold atomic gases and in the solid state. The article also highlights unresolved issues that deserve further investigation.
Article
Optics
S. M. Roccuzzo, A. Recati, S. Stringari
Summary: We show that by studying the time-dependent response of a trapped gas subjected to a sudden rotation, we can determine the moment of inertia of dipolar supersolid configurations. One-dimensional arrays of droplets provide accurate access to the moment of inertia through the frequency of scissors oscillation, while two-dimensional-like configurations exhibit low-frequency resonances indicating the presence of significant rigid body components in the rotational motion.
Article
Physics, Multidisciplinary
S. M. Roccuzzo, S. Stringari, A. Recati
Summary: We investigate the density distributions of a dipolar Bose-Einstein condensed gas confined in a box potential, focusing on the effects of supersolidity. The ground-state density exhibits a depletion in the bulk region and an accumulation of atoms near the walls due to the competition between attractive and repulsive forces. In a quasi-two-dimensional geometry, we observe a ringlike configuration near the boundary of the box, indicating supersolid and crystal effects. In the case of square box trapping, density oscillations along the edges resemble quasi-one-dimensional configurations. Supersolidity can also be observed in the bulk region for large atom numbers, reflecting the symmetry of the confining potential.
PHYSICAL REVIEW RESEARCH
(2022)
