Classification of Symmetry-Protected Phases for Interacting Fermions in Two Dimensions

Recently, it has been shown that two-dimensional bosonic symmetry-protected topological(SPT) phases with on-site unitary symmetry $G$ can be completely classified by the group cohomology class $H^3(G, \mathrm{U}(1))$. Later, group super-cohomology class was proposed as a partial classification for SPT phases of interacting fermions. In this work, we revisit this problem based on the mathematical framework of $G$-extension of unitary braided tensor category(UBTC) theory. We first reproduce the partial classifications given by group super-cohomology, then we show that with an additional $H^1(G, \mathbb{Z}_2)$ structure, a complete classification of SPT phases for two-dimensional interacting fermion systems for a total symmetry group $G\times\mathbb{Z}_2^f$ can be achieved. We also discuss the classification of interacting fermionic SPT phases protected by time-reversal symmetry.Comment: references added; published versio

Universal Bound on Energy Cost of Bit Reset in Finite Time

We consider how the energy cost of bit reset scales with the time duration of the protocol. Bit reset necessarily takes place in finite time, where there is an extra penalty on top of the quasistatic work cost derived by Landauer. This extra energy is dissipated as heat in the computer, inducing a fundamental limit on the speed of irreversible computers. We formulate a hardware-independent expression for this limit in the framework of stochastic processes. We derive a closed-form lower bound on the work penalty as a function of the time taken for the protocol and bit reset error. It holds for discrete as well as continuous systems, assuming only that the master equation respects detailed balance.Comment: Discussions about the tightness and the application of the bound are added. References are updated. 7+10 pages, 3+1 figure

Lycium barbarum polysaccharide attenuates cisplatininduced apoptosis in ovary granulosa cells via alleviation of endoplasmic reticulum stress

Purpose: To investigate the effect of Lycium barbarum polysaccharide (LBP) on apoptosis of ovary granulose cells (GCs), as well as its underlying mechanism.Methods: GCs were isolated from Sprague Dawley (SD) rats and divided into three groups: control group, model group (DDP) and LBP group. Cell morphology was observed by H & E staining under optical microscope. Expression of follicle stimulating hormone receptor (FSHR) was assessed by immunohistochemistry (IHC), while cell viability was assayed using 3-(4,5-dimethyl-2-thiazolyl)-2,5- diphenyl-2-H-tetrazolium bromide (MTT). Apoptosis was determined by flow cytometry. Expressions of glucose-regulated protein 78(GRP78), C/EBP homologous protein (CHOP), caspase-3, Bax protein and B cell lymphoma-2(Bcl-2) were assayed by Western blot and qRT-PCR.Results: Apoptosis index (37.6 ± 2.44 %) was significantly higher (p > 0.05) in DDP group than in the control group (14.3 ± 1.09 %), while mRNA levels and expressions of caspase-3, Bcl-2 and Bax increased significantly (p > 0.05). Expressions of GRP78 and CHOP in the DDP group were also higher than in the control group (p > 0.05). However, these effects were effectively blocked by co-incubation with LBP. Moreover, the DDP-induced increase in apoptosis index was dose-dependently and significantly lowered by LBP (p > 0.05).Conclusion: LBP exerts protective effect on cisplatin-induced apoptosis in ovary granulosa cells by alleviating endoplasmic reticulum stress and regulating levels of apoptosis-related proteins. Thus, LBP has the potential for alleviating adverse effects induced by cisplatin in the treatment of ovary granulosa lesions.Keywords: Cis-platin, Ovary granulosa lesions, Lycium barbarum polysaccharide, Endoplasmic reticulum stress, Apoptosi