Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · cond-mat/0307726

Bosons and Fermions near Feshbach resonances

H. Heiselberg
View original source ↗Read source document ↗Export metadata ↓

Abstract

Near Feshbach resonances, $n|a|^3\gg 1$, systems of Bose and Fermi particles become strongly interacting/dense. In this unitary limit both bosons and fermions have very different properties than in a dilute gas, e.g., the energy per particle approach a value $\hbar^2n^{2/3}/m$ times an universal many-body constant. Calculations based upon an approximate Jastrow wave function can quantitatively describe recent measurements of trapped Bose and Fermi atoms near Feshbach resonances. The pairing gap between attractive fermions also scales as $Δ\sim\hbar^2n^{2/3}/m$ near Feshbach resonances and is a large fraction of the Fermi energy - promising for observing BCS superfluidity in traps. Pairing undergoes several transitions depending on interaction strength and the number of particles in the trap and can also be compared to pairing in nuclei.

Explore related subjects

cond-mat.supr-con

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

H. Heiselberg. 2004-02-06. Bosons and Fermions near Feshbach resonances. https://doi.org/10.1088/0953-4075%2F37%2F7%2F060

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Hidden magnetic order within the pressure induced superconducting dome of UTe2

Unconventional superconductivity typically occurs near magnetic instabilities, and the corresponding spin fluctuations are widely believed to play a crucial role in mediating electron pairing. UTe$_2$ is a promising candidate for exhibiting multiple spin-triplet superconducting phases when tuning with applied pressure and magnetic fields, but the nature of the magnetism driving these unconventional pairing states is undetermined. Our measurements of UTe$_2$ under applied pressures and magnetic fields reveal the presence of a magnetic order hidden within the pressure-induced superconducting dome, which vanishes together with the superconductivity once there is sufficiently high pressure to induce the three-dimensional antiferromagnetic phase. Extrapolation of the phase boundary of the hidden magnetic order, which is most likely antiferromagnetic in nature, points to a zero-temperature quantum critical point that coincides with the maximum transition temperature of the pressure-induced superconducting dome, suggesting that it could corresponds to the parent magnetic phase of the critical antiferromagnetic spin fluctuations driving the triplet superconductivity. These findings advance the understanding of the interplay of magnetism and superconductivity in an exemplar candidate triplet superconductor, which is necessary for revealing the microscopic origin of the different unconventional superconducting phases.

cond-mat.supr-con↗
arXiv2026

Superconducting spin valve as a sensitive probe of spin-orbit coupling anisotropy

Spin-orbit coupling (SOC) plays a central role in modern condensed matter physics and is crucial for the development of spin-based devices and quantum technologies. In particular, the interplay between Rashba SOC (R-SOC), arising from structural inversion asymmetry, and Dresselhaus SOC (D-SOC), due to bulk inversion asymmetry, significantly influences spin coherence and manipulation in two-dimensional and topological systems. Disentangling these SOC components is essential for spintronics, superconducting spintronics, or topological superconductivity. In this study, we experimentally investigate in-plane low-bias conductance anisotropy in epitaxial Fe/MgO/V/MgO/Fe/Co junctions under varying temperature and magnetic field conditions. By applying a theoretical model that accounts for distinct R-SOC and D-SOC contributions, we interpret the observed anisotropy as a reliable method to disentangle these effects. Comparison between experiment and theory reveals a 5 % contribution of D-SOC to total SOC, attributed to periodic interfacial lattice mismatch defects confirmed by high-resolution scanning transmission electron microscopy (STEM). Our findings offer a practical approach to isolate interfacial SOC components in superconducting spintronic systems with implications for engineering in spintronic and quantum devices, and provide further evidence of superconducting spin-triplet pairing in Fe/MgO/V-based superconductor/ferromagnet heterostructures.

cond-mat.supr-con↗
arXiv2026

Nodal Orbital-Anti-Phase Superconducting State in Bilayer Nickelates

The recent discovery of high-$T_c$ superconductivity in the bilayer nickelate La$_3$Ni$_2$O$_7$ (La-327) under applied pressure and compressive strain opened a new avenue to elucidate the interplay between multiorbital intralayer and interlayer electronically driven Cooper-pairing in bilayer systems. Depending on the details of the electronic structure in the normal state, the superconducting gap in bilayer nickelates is predicted to have either bonding-antibonding $s_{\pm}$-wave symmetry, driven by dominant interlayer Cooper-pairing, or $d$-wave symmetry with substantial intralayer Cooper-pairing. Despite this general picture, the orbital structure of the superconducting gap in these multiorbital systems has been less explored. Here, we analyze the consequences of an orbital-anti-phase structure of the superconducting gap and discuss its possible experimental signatures. We demonstrate that additional pairs of nodes may appear on the $α$ and/or $β$ Fermi surface sheets due to the sign change of the superconducting gap between the involved orbitals. Apart from this additional nodal structure, which is not enforced by the symmetries of the gap function and can be probed in ARPES experiments, the orbital-anti-phase gap modifies the temperature dependence of the superfluid stiffness at low temperatures, providing a concrete experimental prediction to test its realization in bilayer nickelates and related multiorbital systems.

cond-mat.supr-con↗