28 research outputs found
Efimov Trimers near the Zero-crossing of a Feshbach Resonance
Near a Feshbach resonance, the two-body scattering length can assume any
value. When it approaches zero, the next-order term given by the effective
range is known to diverge. We consider the question of whether this divergence
(and the vanishing of the scattering length) is accompanied by an anomalous
solution of the three-boson Schr\"odinger equation similar to the one found at
infinite scattering length by Efimov. Within a simple zero-range model, we find
no such solutions, and conclude that higher-order terms do not support Efimov
physics.Comment: 8 pages, no figures, final versio
Entangling identical bosons in optical tweezers via exchange interaction
We first devise a scheme to perform a universal entangling gate via
controlled collisions between pairs of atomic qubits trapped with optical
tweezers. Second, we present a modification to this scheme to allow the
preparation of atomic Bell pairs via selective excitation, suitable for quantum
information processing applications that do not require universality. Both
these schemes are enabled by the inherent symmetries of identical composite
particles, as originally proposed by Hayes et al. Our scheme provides a
technique for producing weighted graph states, entangled resources for quantum
communication, and a promising approach to performing a "loophole free" Bell
test in a single laboratory.Comment: 9 pages, 3 figure
Early carboniferous brachiopod faunas from the Baoshan block, west Yunnan, southwest China
38 brachiopod species in 27 genera and subgenera are described from the Yudong Formation in the Shidian-Baoshan area, west Yunnan, southwest China. New taxa include two new subgenera: Unispirifer (Septimispirifer) and Brachythyrina (Longathyrina), and seven new species: Eomarginifera yunnanensis, Marginatia cylindrica, Unispirifer (Unispirifer) xiangshanensis, Unispirifer (Septimispirifer) wafangjieensis, Brachythyrina (Brachythyrina) transversa, Brachythyrina (Longathyrina) baoshanensis, and Girtyella wafangjieensis. Based on the described material and constraints from associated coral and conodont faunas, the age of the brachiopod fauna from the Yudon Formation is considered late Tournaisian (Early Carboniferous), with a possibility extending into earlyViseacutean.<br /