We report the experimental realization and characterization of one 60-mode copy, and of two 30-mode copies, of a dual-rail quantum-wire cluster state in the quantum optical frequency comb of a bimodally pumped optical parametric oscillator. This is the largest entangled system ever created whose subsystems are all available simultaneously. The entanglement proceeds from the coherent concatenation of a multitude of EPR pairs by a single beam splitter, a procedure which is also a building block for the realization of hypercubic-lattice cluster states for universal quantum computing.PACS numbers: 03.65. Ud,03.67.Bg,42.50.Dv,03.67.Mn, 42.50.Ex , 42.65.Yj Introduction.-Initially identified by Einstein, Podolsky, and Rosen (EPR) [1] as central to testing the completeness of quantum mechanics, entanglement is also crucial to exponential speedups of quantum computing [2][3][4][5]. In the race to build a practical quantum computer [6], the ability to create very large quantum registers and entangle them is paramount, along with the ability to address the issue of decoherence. The study of large-scale entanglement-i.e., multipartite entanglement between numerous subsystems-is in itself an intriguing topic at the forefront of current research, as such systems have yet to be studied in laboratories.Until recently, the largest entangled state of any sort involved 14 trapped ions [7]. Quantum optical systems, which suffer less from decoherence but are harder to entangle, have shown progress, with photon-based, discrete-variable implementations of a 4-qubit "compiled," nonscalable version of Shor's algorithm [8, 9], including in an integrated optics platform [10], 4-qubit blind quantum computing [11], and 8-qubit topological quantum error correction [12].With particular regard to scalability, the field-based, continuous-variable (CV) flavor of quantum optics has high potential [13][14][15][16][17], in particular by enabling "top down," rather than "bottom up," entangling approaches of quantum field modes. It is also important to note the relevance of continuous variables to universal quantum computing, with the recent discovery of a fault tolerance threshold for quantum computing with CV cluster states and nonGaussian error correction [18].In 2011, 15 independent 4-mode cluster states were generated simultaneously over 60 modes of the quantum optical frequency comb (QOFC) of a single optical parametric oscillator (OPO) [19]. In 2013, 10-mode entanglement was observed in a synchronously pumped OPO [20], and 10,000 modes were sequentially entangled into a dual-rail cluster state [21] following a time-domain protocol [22, 23] in which the modes are emitted in pairs and detected in turn, with only a few modes accessible

One-way quantum computing is experimentally appealing because it requires only local measurements on an entangled resource called a cluster state. Record-size, but non-universal, continuous-variable cluster states were recently demonstrated separately in the time and frequency domains. We propose to combine these approaches into a scalable architecture in which a single optical parametric oscillator and simple interferometer entangle up to (3 × 10 3 frequencies) × (unlimited number of temporal modes) into a new and computationally universal continuous-variable cluster state. We introduce a generalized measurement protocol to enable improved computational performance on the new entanglement resource.

Cluster states with higher-dimensional lattices that cannot be physically embedded in three-dimensional space have important theoretical interest in quantum computation and quantum simulation of topologically ordered condensed-matter systems. We present a simple, scalable, top-down method of entangling the quantum optical frequency comb into hypercubic-lattice continuous-variable cluster states of a size of about 10 4 quantum field modes, using existing technology. A hypercubic lattice of dimension D (linear, square, cubic, hypercubic, etc.) requires but D optical parametric oscillators with bichromatic pumps whose frequency splittings alone determine the lattice dimensionality and the number of copies of the state.

We present real-time study of pristine graphene sandwiched in a homogeneous polymer matrix and its phase transition where the graphene membrane irreversibly scrolls and folds above the polymer's glass temperature. Tubular structures tend to form by curling up from edge defects of graphene and roll along its surface. A single-layer can also fold into two- or three-layer stacks and the overlapping between layers extends along the membrane surface to enlarge up to micrometer sizes. Further, oxidized graphene does not show such reactivity at even higher temperatures, indicating that the intrinsic thermal instability of pristine graphene in the polymer matrix is the origin of the transition.

Asymptomatic infection is a big challenge in curbing the spread of COVID-19. However, its identification and pathogenesis elucidation remain issues. Here, by performing comprehensive lipidomic characterization of serum samples from 89 asymptomatic COVID-19 patients and 178 healthy controls, we screened out a panel of 15 key lipids that could accurately identify asymptomatic patients using a new ensemble learning model based on stacking strategy with a voting algorithm. This strategy provided a high accuracy of 96.0% with only 3.6% false positive rate and 4.8% false negative rate. More importantly, the unique lipid metabolic dysregulation was revealed, especially the enhanced synthesis of membrane phospholipids, altered sphingolipids homeostasis, and differential fatty acids metabolic pattern, implicated the specific host immune, inflammatory, and antiviral responses in asymptomatic COVID-19. This study provides a potential pre-diagnostic method for asymptomatic COVID-19 and molecular clues for the pathogenesis and therapy of this disease.