1,849 research outputs found
Towards a complete classification of fermionic symmetry protected topological phases in 3D and a general group supercohomology theory
Classification and construction of symmetry protected topological (SPT)
phases in interacting boson and fermion systems have become a fascinating
theoretical direction in recent years. It has been shown that the (generalized)
group cohomology theory or cobordism theory can give rise to a complete
classification of SPT phases in interacting boson/spin systems. Nevertheless,
the construction and classification of SPT phases in interacting fermion
systems are much more complicated, especially in 3D. In this work, we revisit
this problem based on the equivalent class of fermionic symmetric local unitary
(FSLU) transformations. We construct very general fixed point SPT wavefunctions
for interacting fermion systems. We naturally reproduce the partial
classifications given by special group super-cohomology theory, and we show
that with an additional (the so-called
obstruction free subgroup of ) structure, a complete
classification of SPT phases for three-dimensional interacting fermion systems
with a total symmetry group can be obtained for
unitary symmetry group . We also discuss the procedure of deriving a
general group super-cohomology theory in arbitrary dimensions.Comment: 48 pages, 35 figures, published versio
Bulk induced phase transition in driven diffusive systems
This Letter studies a weakly and asymmetrically coupled three-lane driven
diffusive system. A non-monotonically changing density profile in the middle
lane has been observed. When the extreme value of the density profile reaches
, a bulk induced phase transition occurs which exhibits a shock and a
continuously and smoothly decreasing density profile which crosses
upstream or downstream of the shock. The existence of double shocks has also
been observed. A mean-field approach has been used to interpret the numerical
results obtained by Monte Carlo simulations. The current minimization principle
has excluded the occurrence of two or more bulk induced shocks in the general
case of nonzero lane changing rates
Historical Development of the Undergraduate Educational Model at BIT from the Perspective of Suzhi Education
From the perspective of suzhi education, this study analyses the historical development of the undergraduate educational model at Beijing Institute of Technology (BIT). It could be argued that BIT’s talent-cultivating system’s transformations from 1940 to 2020 echo Chinese higher education’s reform and development. This study concludes that BIT has experienced four phases: (1) from advocacy for general-specialized education’s integration to general education’s disappearance, (2) from the rectification of specialized education to the germination of suzhi and general education, (3) the flourishing of suzhi education and general education, and (4) the establishment of the Shuyuan System. The case of BIT reflects Chinese higher education’s development and the process of transforming from meritocracy to popularization. Chinese universities have changed their paradigm from emphasizing specialized education to highlighting suzhi education, as well as from focusing on training students into specialists to stressing students’ holistic development
- …