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
Ke-Ji Chen, Fan Wu, Lianyi He, Wei Yi
Summary: This study demonstrates that pairing in an ultracold Fermi gas with spin-orbital-angular-momentum coupling can have topological features encoded in the quantized angular degrees of freedom. The resulting topological superfluid, characterized by a Zak phase in the angular-momentum space, is the angular analog of a one-dimensional Fermi gas with spin-orbit coupling. By tuning the parameters of the spin-orbital-angular-momentum coupling, a topological phase transition can occur along with the closing of the quasiparticle excitation gap. Additionally, a topological vortex state can be stabilized by deforming the Fermi surface, offering interesting potential applications in quantum information and control.
PHYSICAL REVIEW RESEARCH
(2022)
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
Yanping Cai, Daniel G. Allman, Parth Sabharwal, Kevin C. Wright
Summary: Researchers have successfully generated persistent currents of ultracold fermionic atoms trapped in a ring, with lifetimes exceeding 10 seconds in the strongly interacting regime. These currents remain stable even in the BCS regime at low temperatures. By manipulating the interaction strength, they were able to switch the circulating BCS superfluid into the normal phase and observed that the probability of quantized superflow reappearing was not significantly affected by the time spent in the normal phase or the minimum interaction strength. This study demonstrates the potential use of ultracold fermionic atoms with tunable interactions in creating matter-wave circuits similar to those previously created with weakly interacting bosonic atoms.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Applied
R. Thomas, J. S. Otto, M. Chilcott, A. B. Deb, N. Kjaergaard
Summary: This method demonstrates the reduction of number fluctuations in an ultracold atomic sample using real-time feedback, based on a proxy value derived from Faraday rotation measurements. Iteratively removing excess atoms from the sample to converge on a target value is shown to be robust to environmental perturbations and light polarization errors. Number fluctuations were reduced from 3% to 0.45% over several hours, with limitations posed by temperature fluctuations, beam-pointing noise, and photon shot noise.
PHYSICAL REVIEW APPLIED
(2021)
Article
Physics, Multidisciplinary
A. Farolfi, A. Zenesini, D. Trypogeorgos, C. Mordini, A. Gallemi, A. Roy, A. Recati, G. Lamporesi, G. Ferrari
Summary: The study successfully achieved effects similar to magnetic junctions using a coherently coupled mixture of ultracold bosonic gases, observing the formation of magnetic interfaces and waves. These results establish ultracold gases as a platform for studying far-from-equilibrium spin dynamics in regimes not easily accessible in solid-state systems.
Article
Materials Science, Multidisciplinary
Janik Schoenmeier-Kromer, Lode Pollet
Summary: We investigate the phase diagram of a one-dimensional Bose-Fermi-Hubbard model with scalar bosons at unit filling and S=1/2 fermions at half filling using quantum Monte Carlo simulations. The fermion-fermion interaction is set to zero. The main focus of our study is to understand the induced interactions between the fermions by the bosons, both for weak and strong interspecies coupling. We find that these induced interactions can result in competing instabilities favoring phase separation, superconducting phases, and density wave structures, often occurring on length scales of more than 100 sites. Additionally, we observe marginal bosonic superfluids with faster decay of the density matrix compared to pure bosonic systems with on-site interactions.
Article
Optics
Xue-Ting Fang, Zheng-Qi Dai, Di Xiang, Shou-Long Chen, Shao-Jun Li, Xiang Gao, Qian-Ru Zhu, Xing Deng, Lushuai Cao, Zhong-Kun Hu
Summary: Research has uncovered that, in the intermediate interaction regime, the categorization of eigenstates is preserved even when the eigenenergy spectrum becomes gapless, due to the mini gap induced by finite-size effects. The disappearance of gaps in the spectrum results in direct and avoided crossings between close-lying manifolds, determined by the combined symmetries of the manifolds.
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
Mathieu Barbier, Henrik Luetjeharms, Walter Hofstetter
Summary: Using trapped Rydberg-excited p states in an optical lattice, the ground-state phase diagram and different regimes of an extended two-component Bose-Hubbard model are studied. The anisotropic interaction is found to be more advantageous for observing supersolid phases compared to the isotropic case.
Article
Optics
Hongmian Shui, Chi-Kin Lai, Zhongcheng Yu, Jinyuan Tian, Chengyang Wu, Xuzong Chen, Xiaoji Zhou
Summary: Ultracold atoms in optical lattices provide a flexible and effective platform for quantum precision measurement. In this work, we investigate the relationship between lattice depth and lifetime of D-band atoms in a triangular optical lattice, and find that there is an optimal lattice depth for achieving the longest lifetime. By loading the Bose-Einstein condensate into the D band using a shortcut method, we observe the atomic distribution in quasi-momentum space for different evolution times and measure the atomic lifetime at different lattice depths. Our experimental results, supported by numerical simulations, show that the lifetime is maximized when the overlaps between the wave function of the D band and other bands (mainly the S band) are minimized. Additionally, we discuss the influence of atomic temperature on the lifetime. This work paves the way for improving the coherence properties of optical lattices and has implications for the development of quantum precision measurement, quantum communication, and quantum computing.
Article
Multidisciplinary Sciences
Inaki Garcia-Elcano, Jaime Merino, Jorge Bravo-Abad, Alejandro Gonzalez-Tudela
Summary: Fermi arcs are surface states connecting topologically distinct Weyl points, which showcase the topological aspects of Weyl physics. We investigate the photonic counterpart of these states and demonstrate unique phenomena. We show how to image the Fermi arcs through the spontaneous decay of emitters coupled to the system's border. We also demonstrate the potential of Fermi arc surface states as a robust quantum link, enabling perfect quantum state transfer and the formation of highly entangled states.
Article
Optics
Mateusz Lacki
Summary: By using an optical potential with subwavelength resolution in the form of sharp delta-like peaks, this study increases the anharmonicity in lattice band energies and enhances the stability of ultracold atom p-band gas.
Article
Materials Science, Multidisciplinary
Zuo Wang, Li-Jun Lang, Liang He
Summary: We investigate the ground state and quantum dynamics of an interacting bosonic chain with nonreciprocal hopping. In systems with noninteger filling, the ground state supports Mott insulators due to the competition between nonreciprocal hopping and the on-site interaction. The conservation laws for non-Hermitian systems show a stark difference compared to their Hermitian counterpart. We establish a generic approach for constructing conserved quantities and illustrate it in the studied system. Mott insulators with noninteger filling and non-Hermitian conservation laws can be observed in ultracold atoms in optical lattices with engineered nonreciprocal hopping.
Article
Physics, Multidisciplinary
Jia-Feng Pan, Jia-Jia Luo, Xi-Wen Guan
Summary: By using an exact Bethe ansatz solution, this study rigorously investigates excitation spectra of the spin-1/2 Fermi gas, discovering different types of excitations such as particle-hole excitations and magnon excitations, and analyzing their properties in depth.
COMMUNICATIONS IN THEORETICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Markus Bohlen, Lennart Sobirey, Niclas Luick, Hauke Biss, Tilman Enss, Thomas Lompe, Henning Moritz
PHYSICAL REVIEW LETTERS
(2020)
Article
Multidisciplinary Sciences
Niclas Luick, Lennart Sobirey, Markus Bohlen, Vijay Pal Singh, Ludwig Mathey, Thomas Lompe, Henning Moritz
Article
Multidisciplinary Sciences
Lennart Sobirey, Niclas Luick, Markus Bohlen, Hauke Biss, Henning Moritz, Thomas Lompe
Summary: This study demonstrates the presence of superfluidity in an ultracold 2D Fermi gas by observing no dissipation below a critical velocity v(c) when moving a periodic potential through the system. The researchers found a maximum in the crossover regime between bosonic and fermionic superfluidity as they measured v(c) as a function of interaction strength. The measurements enable systematic studies of the influence of reduced dimensionality on fermionic superfluidity.
Article
Physics, Multidisciplinary
Lennart Sobirey, Hauke Biss, Niclas Luick, Markus Bohlen, Henning Moritz, Thomas Lompe
Summary: Understanding the origins of unconventional superconductivity has been a major focus of condensed matter physics. In this study, dilute gases of ultracold fermionic atoms were used to observe the influence of dimensionality on the stability of strongly interacting fermionic superfluids. The researchers found that the superfluid gap follows a universal function, suggesting that there is no inherent difference in the stability of two-and three-dimensional fermionic superfluids.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Aleksi Julku, Jami J. Kinnunen, Arturo Camacho-Guardian, Georg M. Bruun
Summary: It is demonstrated that electrons interacting with a Bose-Einstein condensate (BEC) of exciton-polaritons can realize a two-dimensional topological p(x) + ip(y) superconductor. This is caused by an attractive interaction mediated by the BEC, which overcompensates the repulsive Coulomb interaction between the electrons. The hybrid light-matter nature of the BEC is crucial for achieving this.
Article
Optics
Martin Schlederer, Alexandra Mozdzen, Thomas Lompe, Henning Moritz
Summary: A modified scheme is proposed to address the issue of stringent minimization of stray light from the MOT beams, achieving reliable discrimination of up to 17 K-40 atoms with classification fidelities of similar to 98% for up to 5 atom numbers and fidelities of more than 85% for up to 17 atoms.
