Prompted by recent reports on √3×√3 graphene superlattices with intrinsic inter-valley interactions, we perform first-principles calculations to investigate the electronic properties of periodically nitrogen- ...Prompted by recent reports on √3×√3 graphene superlattices with intrinsic inter-valley interactions, we perform first-principles calculations to investigate the electronic properties of periodically nitrogen- doped graphene and carbon nanotube nanostruetures. In these structures, nitrogen atoms substitute one-sixth of the carbon atoms in the pristine hexagonal lattices with exact periodicity to form perfect √3×√3 superlattices of graphene and carbon nanotubes. Multiple nanostructures of √3×√3 graphene ribbons and carbon nanotubes are explored, and all configurations show nonmagnetic and metallic behaviors. The transport properties of √3×√3 graphene and carbon nanotube superlattices are calculated utilizing the non-equilibrium Green＇s function formalism combined with density functional theory. The translnission spectrum through the pristine and √3×√3 armchair carbon nanotube heterostructure shows quantized behavior under certain circumstances.展开更多
We study the spontaneous decoherence of coupled harmonic oscillators confined in a ring container, where the nearest-neighbor harmonic potentials are taken into consideration. Without any external symmetry-breaking fi...We study the spontaneous decoherence of coupled harmonic oscillators confined in a ring container, where the nearest-neighbor harmonic potentials are taken into consideration. Without any external symmetry-breaking field or surrounding environment, the quantum superposition state prepared in the relative degrees of freedom gradually loses its quantum coherence spontaneously.This spontaneous decoherence is interpreted by the gauge couplings between the center-of-mass and the relative degrees of freedoms, which actually originate from the symmetries of the ring geometry and the corresponding nontrivial boundary conditions.In particular, such spontaneous decoherence does not occur at all at the thermodynamic limit because the nontrivial boundary conditions become the trivial Born-von Karman boundary conditions when the perimeter of the ring container tends to infinity.Our investigation shows that a thermal macroscopic object with certain symmetries has a chance for its quantum properties to degrade even without applying an external symmetry-breaking field or surrounding environment.展开更多
基金This work was financially supported by the National Natural Science Foundation of China （Grants Nos. 11504240~ 11504241, and 11604213）, and the Natural Science Foundation of Shenzhen University （Grant No. 201550）. Z. Y. ac- knowledges the University Grant Council （Contract No. AoE/P- 04/08） of the Government of HKSAR.
文摘Prompted by recent reports on √3×√3 graphene superlattices with intrinsic inter-valley interactions, we perform first-principles calculations to investigate the electronic properties of periodically nitrogen- doped graphene and carbon nanotube nanostruetures. In these structures, nitrogen atoms substitute one-sixth of the carbon atoms in the pristine hexagonal lattices with exact periodicity to form perfect √3×√3 superlattices of graphene and carbon nanotubes. Multiple nanostructures of √3×√3 graphene ribbons and carbon nanotubes are explored, and all configurations show nonmagnetic and metallic behaviors. The transport properties of √3×√3 graphene and carbon nanotube superlattices are calculated utilizing the non-equilibrium Green＇s function formalism combined with density functional theory. The translnission spectrum through the pristine and √3×√3 armchair carbon nanotube heterostructure shows quantized behavior under certain circumstances.
基金supported by the National Natural Science Foundation of China(Grant Nos.11504241,and 11374032)the National Key Basic Research Program(Grant No.2014CB848700)Natural Science Foundation of Shenzhen University(Grants No.201551)
文摘We study the spontaneous decoherence of coupled harmonic oscillators confined in a ring container, where the nearest-neighbor harmonic potentials are taken into consideration. Without any external symmetry-breaking field or surrounding environment, the quantum superposition state prepared in the relative degrees of freedom gradually loses its quantum coherence spontaneously.This spontaneous decoherence is interpreted by the gauge couplings between the center-of-mass and the relative degrees of freedoms, which actually originate from the symmetries of the ring geometry and the corresponding nontrivial boundary conditions.In particular, such spontaneous decoherence does not occur at all at the thermodynamic limit because the nontrivial boundary conditions become the trivial Born-von Karman boundary conditions when the perimeter of the ring container tends to infinity.Our investigation shows that a thermal macroscopic object with certain symmetries has a chance for its quantum properties to degrade even without applying an external symmetry-breaking field or surrounding environment.
