A quantum memory, for storing and retrieving flying photonic quantum states, is a key interface for realizing long-distance quantum communication and large-scale quantum computation. While many experimental schemes of high storage-retrieval efficiency have been performed with weak coherent light pulses, all quantum memories for true single photons achieved so far have efficiencies far below 50%, a threshold value for practical applications. Here, we report the demonstration of a quantum memory for single-photon polarization qubits with an efficiency of >85% and a fidelity of >99%, basing on balanced two-channel electromagnetically induced transparency in laser-cooled rubidium atoms. For the singlechannel quantum memory, the optimized efficiency for storing and retrieving single-photon temporal waveforms can be as high as 90.6%. Our result pushes the photonic quantum memory closer to its practical applications in quantum information processing.

Topologically protected states are observed in engineered optical lattices with ultracold fermions.

Background: Circular RNAs (circRNAs) represent a class of non-coding RNAs (ncRNAs) which are widely expressed in mammals and tissue-specific, of which some could act as critical regulators in the atherogenesis of cerebrovascular disease. However, the underlying mechanisms by which circRNA regulates the ectopic phenotype of endothelial cells (ECs) in atherosclerosis remain largely elusive. Methods: CCK-8, transwell, wound healing and Matrigel assays were used to assess cell viability, migration and tube formation. QRT-qPCR and Immunoblotting were used to examine targeted gene expression in different groups. The binding sites of miR-370-3p (miR-370) with TGFβR2 or hsa_circ_0003204 (circ_0003204) were predicted using a series of bioinformatic tools, and validated using dual luciferase assay and RNA immunoprecipitation (RIP) assay. The localization of circ_0003204 and miR-370 in ECs were investigated by fluorescence in situ hybridization (FISH). Gene function and pathways were enriched through Metascape and gene set enrichment analysis (GSEA). The association of circ_0003204 and miR-370 in extracellular vesicles (EVs) with clinical characteristics of patients were investigated using multiple statistical analysis. Results: Circ_0003204, mainly located in the cytoplasm of human aorta endothelial cells (HAECs), was upregulated in the ox-LDL-induced HAECs. Functionally, the ectopic expression of circ_0003204 inhibited proliferation, migration and tube formation of HAECs exposed to ox-LDL. Mechanically, circ_0003204 could promote protein expression of TGFβR2 and its downstream phosph-SMAD3 through sponging miR-370, and miR-370 targeted the 3′ untranslated region (UTR) of TGFβR2. Furthermore, the expression of circ_0003204 in plasma EVs was upregulated in the patients with cerebral atherosclerosis, and represented a potential biomarker for diangnosis and prognosis of cerebrovascular atherogenesis. Conclusions: Circ_0003204 could act as a novel stimulator for ectopic endothelial inactivation in atherosclerosis and a potential biomarker for cerebral atherosclerosis.

We demonstrate all-optical implementation of spin-orbit coupling (SOC) in a two-electron Fermi gas of 173 Yb atoms by coupling two hyperfine ground states with a narrow optical transition. Due to the SU(N ) symmetry of the 1 S0 ground-state manifold which is insensitive to external magnetic fields, an optical AC Stark effect is applied to split the ground spin states, which exhibits a high stability compared with experiments on alkali and lanthanide atoms, and separate out an effective spin-1/2 subspace from other hyperfine levels for the realization of SOC. The dephasing spin dynamics when a momentum-dependent spin-orbit gap being suddenly opened and the asymmetric momentum distribution of the spin-orbit coupled Fermi gas are observed as a hallmark of SOC. The realization of all-optical SOC for ytterbium fermions should offer a new route to a long-lived spin-orbit coupled Fermi gas and greatly expand our capability in studying novel spin-orbit physics with alkaline-earth-like atoms.Ultracold atoms are fascinating for the study of synthetic quantum system which is direct analogy to real electronic material [1]. One of the notable examples is the implementation of synthetic gauge field and spinorbit coupling (SOC) engineered with the atom-light interaction at will [2,3]. In particular, SOC links a particle's spin with its momentum, which is not only essential in novel quantum phenomena, such as spintronic effect [4] and exotic topological states of quantum matter [5,6], but also provides an unprecedented quantum system such as spin-half spin-orbit coupled bosons without analogy in condensed-matter [7]. Various types of SOCs can be generated in ultracold atoms where the relevant parameters are tunable by changing the laser fields [8][9][10] or the magnetic field [11]. So far, the SOCs along the one direction have been created in bosonic alkali [7,[12][13][14][15][16][17][18][19], fermionic alkali atoms [20][21][22][23], and very recently in fermionic lanthanide atoms [24]. Besides the 1D SOC, the two-dimensional synthetic SOCs have been also demonstrated both in the bosonic [25] and fermionic alkali atoms [26].In alkali atoms, two different internal states are coupled through the Raman transition transferring momentum to the atoms [2,3]. However those processes inevitably suffer from heating effect caused by spontaneous emission due to the small fine-structure splitting of the excited level, which could limit the ability to observe interacting many-body phenomena that needs long timescales. Recently to avoid such heating, the specific atomic species with the large ground-state angular momentum such as 161 Dy have been considered [27,28] or the external orbital states, representing pseudo-spins, in optical superlattices have been used to generate SOC [29,30].Here, we expand our capability in exploring a novel SOC physics by implementing SOC with a narrow optical transition in a non-alkali Fermi gas of ytterbium atoms. With a momentum-dependent spin-orbit gap being suddenly opened by switching on the Raman transitio...