5,000 research outputs found
Large Margin Neural Language Model
We propose a large margin criterion for training neural language models.
Conventionally, neural language models are trained by minimizing perplexity
(PPL) on grammatical sentences. However, we demonstrate that PPL may not be the
best metric to optimize in some tasks, and further propose a large margin
formulation. The proposed method aims to enlarge the margin between the "good"
and "bad" sentences in a task-specific sense. It is trained end-to-end and can
be widely applied to tasks that involve re-scoring of generated text. Compared
with minimum-PPL training, our method gains up to 1.1 WER reduction for speech
recognition and 1.0 BLEU increase for machine translation.Comment: 9 pages. Accepted as a long paper in EMNLP201
Dynamical quantum phase transitions in quantum link models
Quantum link models are extensions of Wilson-type lattice gauge theories
which realize exact gauge invariance with finite-dimensional Hilbert spaces.
Quantum link models not only reproduce the standard features of Wilson's
lattice gauge theories, but also host new phenomena such as crystalline
confined phases. We study the non-equilibrium quench dynamics for two
representative cases, quantum link models in (1+1)d and (2+1)d, through
the lens of dynamical quantum phase transitions. Finally, we discuss the
connection to the high-energy perspective and the experimental feasibility to
observe the discussed phenomena in recent quantum simulator settings such as
trapped ions, ultra-cold atoms, and Rydberg atoms.Comment: 8 pages, 8 figure
High-energy electronic excitations in SrIrO observed by Raman scattering
Spin-orbit interaction in SrIrO leads to the realization of the
= 1/2 state and also induces an insulating behavior. Using
large-shift Raman spectroscopy, we found two high-energy excitations of the
d-shell multipletat at 690 meV and 680 meV with and symmetry
respectively. As temperature decreases, the and peaks narrow,
and the peak shifts to higher energy while the energy of the
peak remains the same. When 25 of Ir is substituted with Rh the
peak softens by 10 but the peak does not. We show that both
pseudospin-flip and non-pseudosin-flip dd electronic transitions are Raman
active, but only the latter are observed
Quantum phase diagrams of fermionic dipolar gases for an arbitrary orientation of dipole moment in a planar array of 1D tubes
We systematically study ground state properties of fermionic dipolar gases in
a planar array of one-dimensional potential tubes for an arbitrary orientation
of dipole moments. Using the Luttinger liquid theory with the generalized
Bogoliubov transformation, we calculate the elementary excitations and the
Luttinger scaling exponents for various relevant quantum orders. The complete
quantum phase diagrams for arbitrary polar angle of the dipole moment is
obtained, including charge density wave, p-wave superfluid, inter-tube
gauge-phase density wave, and inter-tube s-wave superfluid, where the last two
breaks the U(1) gauge symmetry of the system (conservation of particle number
in each tube) and occurs only when the inter-tube interaction is larger than
the intra-tube interaction. We then discuss the physical properties of these
many-body phases and their relationship with some solid state systems.Comment: 10 pages and 10 figure
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