Super-Tonks-Girardeau gas of spin-1/2 interacting fermions

Fermi gases confined in tight one-dimensional waveguides form two-particle bound states of atoms in the presence of a strongly attractive interaction. Based on the exact solution of the one-dimensional spin-1/2 interacting Fermi gas, we demonstrate that a stable excited state with no pairing between attractive fermionic atoms can be realized by a sudden switch of interaction from strongly repulsive regime to the strongly attractive regime. Such a state is an exact fermionic analog of the experimentally observed super-Tonks-Girardeau state of bosonic Cesium atoms [Science 325, 1224 (2009)] and should be possible to be observed by the experiment. The frequency of lowest breathing mode of the fermionic super-Tonks-Girardeau gas is calculated as a function of the interaction strength, which could be used as a detectable signature for the experimental observation.Comment: 4.1 pages, 5 figures, version accepted for publication in Phys. Rev. Let

Strongly Interacting Quantum Gases in One-Dimensional Traps

Under the second-order degenerate perturbation theory, we show that the physics of $N$ particles with arbitrary spin confined in a one dimensional trap in the strongly interacting regime can be described by super-exchange interaction. An effective spin-chain Hamiltonian (non-translational-invariant Sutherland model) can be constructed from this procedure. For spin-1/2 particles, this model reduces to the non-translational-invariant Heisenberg model, where a transition between Heisenberg anti-ferromagnetic (AFM) and ferromagnetic (FM) states is expected to occur when the interaction strength is tuned from the strongly repulsive to the strongly attractive limit. We show that the FM and the AFM states can be distinguished in two different methods: the first is based on their distinct response to a spin-dependent magnetic gradient, and the second is based on their distinct momentum distribution. We confirm the validity of the spin-chain model by comparison with results obtained from several unbiased techniquesComment: 14 pages, 7 figure

Bias in Stabilized Sieve Sampling

The stabilized sieve sample selection method (SSM) is considered to be a probability proportional to size (PPS) sampling method with an unbiased estimator (Horgan 1997, 1998). This article demonstrates that SSM does not select items with PPS and that the point estimator is biased

Role of Trust and Involvement in the Effectiveness of Digital Third-Party Organization Endorsement

In this research, an online experiment was conducted to investigate the effect of the mere presence of digital third-party organization (TPO) endorsement and the quality of information conveyed by a digital TPO, referred to as the endorsement information value effect. Involvement and institution-based trust were tested as moderators of the endorsement information value effect. The results confirm the intuitive belief of managers that the mere presence of a digital TPO endorsement benefits websites by reducing risk perceptions, improving attitudes and increasing choice likelihood. The findings from this research revealed that effectiveness of digital TPO endorsement information value was contingent upon the level of involvement with the effects being found only among high involvement consumers but not among low involvement consumers. Similarly, effectiveness of digital TPO endorsement information value is also contingent on institution-based trust, with the effect of endorsement information value emerging only for low institution-based trust consumers but not for high institution-based trust consumers. Thus, a higher information value digital TPO will increase choice over a low information value digital TPO only if the consumer is highly involved or has low institution-based trust