4,701 research outputs found
Exotic phase separation in one-dimensional hard-core boson system with two- and three-body interactions
We investigate the ground state phase diagram of hard-core boson system with
repulsive two-body and attractive three-body interactions in one-dimensional
optic lattice. When these two interactions are comparable and increasing the
hopping rate, physically intuitive analysis indicates that there exists an
exotic phase separation regime between the solid phase with charge density wave
order and superfluid phase. We identify these phases and phase transitions by
numerically analyzing the density distribution, structure factor of
density-density correlation function, three-body correlation function and von
Neumann entropy estimator obtained by density matrix renormalization group
method. These exotic phases and phase transitions are expected to be observed
in the ultra-cold polar molecule experiments by properly tuning interaction
parameters, which is constructive to understand the physics of ubiquitous
insulating-superconducting phase transitions in condensed matter systems
Quantum resource studied from the perspective of quantum state superposition
Quantum resources,such as discord and entanglement, are crucial in quantum
information processing. In this paper, quantum resources are studied from the
aspect of quantum state superposition. We define the local superposition (LS)
as the superposition between basis of single part, and nonlocal superposition
(NLS) as the superposition between product basis of multiple parts. For quantum
resource with nonzero LS, quantum operation must be introduced to prepare it,
and for quantum resource with nonzero NLS, nonlocal quantum operation must be
introduced to prepare it. We prove that LS vanishes if and only if the state is
classical and NLS vanishes if and only if the state is separable. From this
superposition aspect, quantum resources are categorized as superpositions
existing in different parts. These results are helpful to study quantum
resources from a unified frame.Comment: 9 pages, 4 figure
Entanglement and quantum discord dynamics of two atoms under practical feedback control
We study the dynamics of two identical atoms resonantly coupled to a
single-mode cavity under practical feedback control, and focus on the detection
inefficiency. The entanglement is induced to vanish in finite time by the
inefficiency of detection. Counterintuitively, the asymptotic entanglement and
quantum discord can be increased by the inefficiency of detection. The noise of
detection triggers control field to create entanglement and discord when no
photon are emitted from the atoms. Furthermore, sudden change happens to the
dynamics of entanglement.Comment: 5 pages, 4 figure
- …