Article
Optics
Jinzhu Jiang, Jia-Hui Zhang, Feng Mei, Zhonghua Ji, Ying Hu, Jie Ma, Liantuan Xiao, Suotang Jia
Summary: The recent experimental realization of optical tweezer arrays of ultracold molecules has provided a versatile platform for exploring different molecular phases of matter. By programming tweezers, researchers have been able to tailor dipolar interactions in an optical tweezer ladder to implement a generalized Su-Schrieffer-Heeger model, leading to the discovery of various chiral and interacting topological phases with richer topological edge states. Detection and robustness of these topological phases have also been discussed.
Article
Optics
Kazuya Nishimura, Eiji Nakano, Kei Iida, Hiroyuki Tajima, Takahiko Miyakawa, Hiroyuki Yabu
Summary: This study investigates the properties of Fermi polarons formed by impurity atoms in ultracold atomic Fermi gases, showing that these properties exhibit spatial anisotropies reflecting the momentum anisotropy of the background dipolar Fermi gas. The effective mass and momentum drag parameter of the polaron both tend to decrease by approximately 10% as the DDI strength increases up to its critical value, while the longitudinal properties show weak dependence on the DDI.
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
Hui Tan, Jinsen Han, Wei Zheng, Jianmin Yuan, Yongqiang Li
Summary: This study successfully manipulates the orbital degree of freedom in strongly correlated quantum gases by coupling them to optical cavities. By controlling the reflection of the pump laser, atoms can be selectively transferred to odd-parity or even-parity orbital bands, accompanied by pronounced cavity-photon excitations. Through the interaction with the cavity field, atoms organize into stable higher-orbital superfluid and Mott-insulating phases with orbital-density waves.
Article
Physics, Multidisciplinary
Yann Kiefer, Max Hachmann, Andreas Hemmerich
Summary: Quantum gas systems are used to study the transition between Bose-Einstein condensed molecular pairs and Bardeen-Cooper-Schrieffer superfluidity. Previous studies in optical lattices focused on the lowest Bloch band, excluding orbital degrees of freedom. In this study, ultracold Feshbach molecules of fermionic atoms are prepared in the second Bloch band of an optical square lattice. The preparation covers a wide range of interaction strengths and demonstrates the interplay between orbital physics and the crossover of Bose-Einstein condensation and Bardeen-Cooper-Schrieffer superfluidity.
Article
Physics, Multidisciplinary
G. Bougas, S. Mistakidis, P. Giannakeas, P. Schmelcher
Summary: The few-body correlations emerging in two-dimensional harmonically trapped mixtures were comprehensively investigated, revealing the formation of atom-dimer and trap states, in addition to trimers. The Tan's contacts of these eigenstates were studied, showing enhanced correlations in trimer states compared to other eigenstates. An upper bound was found in the two-body contact of atom-dimer and trap states, while no such bound existed in the three-body contact.
NEW JOURNAL OF PHYSICS
(2021)
Article
Optics
Andrzej Syrwid
Summary: The tutorial discusses the application of solitons in the quantum world and introduces the Lieb-Liniger and Yang-Gaudin models in ultracold Bose and Fermi systems. These models are exactly solvable using the Bethe ansatz technique, aiding in the exploration of the quantum nature of solitonic excitations.
JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS
(2021)
Article
Physics, Multidisciplinary
Yun Long, Feng Xiong, Colin Parker
Summary: Experimental results show that the spin susceptibility is reduced for all significant interaction strengths and at all temperatures compared to a noninteracting Fermi gas. The integrated spin susceptibility for the uniform gas can be extracted using the local density approximation at unitarity, revealing deviations from theoretical predictions at high temperatures. A simple one-parameter mean field model can describe the curve of spin susceptibility at low temperatures.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
P. Ilzhoefer, M. Sohmen, G. Durastante, C. Politi, A. Trautmann, G. Natale, G. Morpurgo, T. Giamarchi, L. Chomaz, M. J. Mark, F. Ferlaino
Summary: The study investigates the response of dipolar supersolids to interaction quenches, finding a parameter regime where the out-of-equilibrium state rephases before gradually relaxing into an incoherent droplet array. Collective mode excitations caused by the interaction quench connect to phonons in solids and affect the phase dynamics.
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, Multidisciplinary
Hauke Biss, Lennart Sobirey, Niclas Luick, Markus Bohlen, Jami J. Kinnunen, Georg M. Bruun, Thomas Lompe, Henning Moritz
Summary: In this work, we measured the excitation spectrum of strongly interacting ultracold Fermi gases using Bragg spectroscopy. The study revealed the smooth transformation from a bosonic to a fermionic superfluid in the BEC-BCS crossover. The results are in excellent agreement with previous experiments and calculations, especially when particle-hole correlations are taken into account.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Bruno M. Faigle-Cedzich, Jan M. Pawlowski, Christof Wetterich
Summary: The study investigates the dimensional crossover from three to two dimensions in an ultracold Fermi gas, particularly focusing on the strongly interacting regime where strong correlations and pair fluctuations are more pronounced. Results are obtained from first principles within the framework of the functional renormalization group (FRG) and calculations are carried out across a wide range of transversal confinement length scales. Emphasis is placed on determining the finite-temperature phase diagram for different confinement length scales and comparing the results with recent experimental observations and other theoretical works.
Article
Multidisciplinary Sciences
Tomasz Swislocki, Mariusz Gajda, Miroslaw Brewczyk, Piotr Deuar
Summary: The study identifies two different mechanisms for spin distillation in Cr-52 and No-23 atoms, involving dipolar scattering and equilibrium relaxation of the thermal cloud. Through numerical simulations, it is demonstrated that the spin distillation cycle can be repeated multiple times, resulting in significant reduction of the thermal atom fraction. Threshold values of magnetic field and predictions for achievable temperature are also identified.
SCIENTIFIC REPORTS
(2021)
Article
Optics
Donghao Li, Guoqi Bian, Jie Miao, Pengjun Wang, Zengming Meng, Liangchao Chen, Lianghui Huang, Jing Zhang
Summary: The study reports the measurement of the Rydberg excitation spectrum in ultra-cold (40K) Fermi gases through a two-photon process. Two methods were employed, one to reduce atomic losses using electromagnetically induced transparency, and the other to enhance losses through spontaneous avalanche ionization due to strong Rydberg-Rydberg interactions. The highest detectable Rydberg states were limited to n <= 62 due to competition between the long Rydberg blockade effective range and limited atomic cloud size.
Article
Astronomy & Astrophysics
M. N. Chernodub
Summary: In this paper, the effects of rotation on the confining properties of gauge theories, with a focus on compact electrodynamics in two spatial dimensions, are discussed. It is shown that rotation leads to a deconfining transition at a certain distance from the rotation axis, creating a mixed inhomogeneous phase in a uniformly rotating confining system. This has implications for the phase diagram of QCD, suggesting an inverse hadronization effect for uniformly rotating quark-gluon plasma.
Article
Physics, Multidisciplinary
Sankar Das Sarma
Summary: Majorana particles, which are the same as their antiparticles, show promise for quantum computing in condensed matter systems. This article discusses the search for Majorana modes in semiconductor heterostructures and the limitations imposed by disorder. Majorana zero modes are emergent phenomena in topological superconductors, and this Perspective provides an overview of their physics, recent experimental progress, and future outlook for success.
Article
Physics, Multidisciplinary
DinhDuy Vu, Sankar Das Sarma
Summary: An ergodic system subjected to an external periodic drive will be heated to infinite temperature, but this heating can be stopped during a prethermal period if the applied frequency is larger than the typical energy scale of the local Hamiltonian. This prethermal period exhibits an emergent symmetry that, if broken, leads to subharmonic oscillation of the discrete time crystal (DTC). The presence of dissipation affects the survival time of the prethermal DTC, with a bath coupling prolonging the prethermal period and interaction with the environment destabilizing spontaneous symmetry breaking, resulting in a nonmonotonic variation of the survival time.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Jiabin Yu, Ming Xie, Fengcheng Wu, Sankar Das Sarma
Summary: Signatures of nematic nodal superconductivity have been observed in magic angle twisted bilayer graphene. Researchers propose a general topological mechanism explaining how nematic pairing leads to nodal superconductivity in this material.
Article
Materials Science, Multidisciplinary
Prathyush P. Poduval, Sankar Das Sarma
Summary: We theoretically investigate the issue of doping induced insulator to metal transition in bulk semiconductors by analyzing the density-dependent mean free path and the Anderson localization transition controlled by the Ioffe-Regel-Mott (IRM) criterion. We calculate the mean free path on the highly doped metallic side considering carrier scattering by ionized dopants. The Coulomb disorder of the charged dopants is screened by the carriers themselves, leading to an integral equation for localization. By solving this equation analytically and numerically, we provide detailed results for the critical density of the doping induced metal-insulator transition.
Article
Materials Science, Multidisciplinary
Nathan L. Foulk, Sankar Das Sarma
Summary: We demonstrate the potential realization of quantum Floquet matter, particularly the discrete time crystal (DTC), using modern silicon spin qubits based in quantum dots. This is significant as silicon spin qubits have advantages in dealing with charge noise. We show the differences between prethermal phenomena and true time-crystalline spatiotemporal order, and illustrate rich regime structures in a spin chain of four qubits that are distinct from the thermal regime.
Article
Materials Science, Multidisciplinary
Seth M. Davis, Yang-Zhi Chou, Fengcheng Wu, Sankar Das Sarma
Summary: We calculate the theoretical contribution of scattering by acoustic phonons to the doping and temperature dependence of electrical resistivity in Bernal bilayer graphene (BBG) and rhombohedral trilayer graphene (RTG). The nontrivial geometric features of the band structures of these systems strongly influence the resistivity's temperature and doping dependencies. Our focus on BBG and RTG is motivated by recent experiments in these systems that have discovered exotic low-temperature superconductivity. The understanding of the influence of band geometry on transport is crucial in these systems.
Article
Materials Science, Multidisciplinary
Haining Pan, Sankar Das Sarma
Summary: Motivated by the presence of Majorana zero modes in both the Kitaev chain model and the experimental semiconductor-superconductor Majorana nanowire, this theoretical study investigates the equivalence or similarity between the two models from the perspective of their corresponding dual spin models. By using the Jordan-Wigner transformation, the duality between the Kitaev chain and the transverse-field XY spin model is established, aiming to connect the Kitaev chain and the nanowire. The application of the Jordan-Wigner transformation to the nanowire reveals that the corresponding bosonic spin model is a generalized spin cluster model with staggered couplings. By projecting out the higher energy band of the spinful nanowire system, an effective low-energy spinless system is obtained, leading to the connection between the Kitaev chain and Majorana nanowire.
Article
Materials Science, Multidisciplinary
Yi-Ting Tu, Sankar Das Sarma
Summary: We analyze an experimental work which shows the failure of the Wiedemann-Franz law in graphene at low temperatures, attributing this failure to the non-Fermi liquid nature of the Dirac fluid. Despite theoretical efforts, the observations remain unexplained. Our analysis suggests that the opening of a gap at the Dirac point induced by the substrate may explain the results. Further experiments are needed to resolve the issue and determine the role of electron and hole transport in the presence of disorder and phonons.
Article
Materials Science, Multidisciplinary
Yi-Ting Tu, DinhDuy Vu, S. Das Sarma
Summary: Coupling a one-dimensional quasiperiodic interacting system to a Markovian bath, this study investigates the avalanche instability of the many-body localized phase numerically. The results show that many-body localization (MBL) is more stable in pseudorandom quasiperiodic systems than in randomly disordered systems for a disorder strength W > 8, potentially up to arbitrarily large system sizes. Real-space RG arguments support this conclusion and a detailed comparison between quasiperiodic and random MBL from the avalanche instability perspective reveals that they belong to different universality classes.
Article
Materials Science, Multidisciplinary
Donovan Buterakos, Sankar Das Sarma
Summary: We discuss interesting phenomena in the Hubbard model related to flat-band ferromagnetism. The first is a mathematical theorem that describes the conditions for degeneracy between a flat-band ferromagnetic and a nonferromagnetic state. This theorem is generally applicable and independent of geometry, but only holds for a small number of holes in a filled band. The second phenomenon challenges intuition by showing an example where particles do not prefer to doubly occupy low-energy states before filling higher-energy states. Lastly, we present a pattern of ferromagnetism in small pentagonal and hexagonal plaquettes at specific filling factors. These examples can be observed in quantum dot arrays available in laboratories.
Article
Materials Science, Multidisciplinary
Yi-Hua Lai, Sankar Das Sarma, Jay D. Sau
Summary: Despite recent progress in experimental observations of large zero-bias conductance peaks, it is still unclear whether Majorana modes have been observed. The existing experimental works lack stability of the putative Majorana mode features, indicating the absence of a topological phase. This paper introduces a dimensionless quality factor F to quantify the robustness of the zero-bias conductance peak height and proposes specific experimentally accessible measures for analyzing the stability of the observed peaks. The results show that Majorana modes are significantly more robust compared to nontopological peaks in the low-temperature limit and suggest that the quality factor F can be used to estimate the quality of topological qubits made from Majorana modes.
Article
Materials Science, Multidisciplinary
Jiabin Yu, Yu-An Chen, Sankar Das Sarma
Summary: This study generalizes the topologically obstructed pairings between Chern states by proposing Euler obstructed Cooper pairing in 3D systems. The Euler obstructed pairing widely exists between two Fermi surfaces with nontrivial band topology and can lead to nodal superconductivity and hinge Majorana zero modes under certain conditions.
Article
Materials Science, Multidisciplinary
Yang-Zhi Chou, Fengcheng Wu, Jay D. Sau, Sankar Das Sarma
Summary: This article presents a systematic theory of acoustic-phonon-mediated superconductivity that incorporates Coulomb repulsion and explains recent experiments in Bernal bilayer graphene. The theory predicts that s-wave spin-singlet and f-wave spin-triplet pairings are degenerate and dominant. The results indicate that the observed spin-triplet superconductivity in Bernal bilayer graphene arises from acoustic phonons.
Article
Materials Science, Multidisciplinary
Seongjin Ahn, Sankar Das Sarma
Summary: We developed a minimal theory for the metal-insulator transition observed in two-dimensional moire multilayer transition metal dichalcogenides, attributing it to Coulomb disorder in the environment. Carrier scattering by random charged impurities leads to an effective 2D MIT roughly controlled by the Ioffe-Regel criterion, with necessary random charged impurity content consistent with known levels in TMDs.
Article
Materials Science, Multidisciplinary
Haining Pan, Sankar Das Sarma
Summary: This study theoretically investigates the strong correlation and symmetry breaking behaviors in two-dimensional moire transition metal dichalcogenide bilayers. The dependence of symmetry breaking on the range of electron-electron interaction and temperature is examined, with implications for experimental control and thermal suppression.