@inproceedings{10324, abstract = {Off-chain protocols (channels) are a promising solution to the scalability and privacy challenges of blockchain payments. Current proposals, however, require synchrony assumptions to preserve the safety of a channel, leaking to an adversary the exact amount of time needed to control the network for a successful attack. In this paper, we introduce Brick, the first payment channel that remains secure under network asynchrony and concurrently provides correct incentives. The core idea is to incorporate the conflict resolution process within the channel by introducing a rational committee of external parties, called wardens. Hence, if a party wants to close a channel unilaterally, it can only get the committee’s approval for the last valid state. Additionally, Brick provides sub-second latency because it does not employ heavy-weight consensus. Instead, Brick uses consistent broadcast to announce updates and close the channel, a light-weight abstraction that is powerful enough to preserve safety and liveness to any rational parties. We formally define and prove for Brick the properties a payment channel construction should fulfill. We also design incentives for Brick such that honest and rational behavior aligns. Finally, we provide a reference implementation of the smart contracts in Solidity.}, author = {Avarikioti, Zeta and Kokoris Kogias, Eleftherios and Wattenhofer, Roger and Zindros, Dionysis}, booktitle = {25th International Conference on Financial Cryptography and Data Security}, isbn = {9-783-6626-4330-3}, issn = {1611-3349}, location = {Virtual}, pages = {209--230}, publisher = {Springer Nature}, title = {{Brick: Asynchronous incentive-compatible payment channels}}, doi = {10.1007/978-3-662-64331-0_11}, volume = {12675 }, year = {2021}, } @article{10363, abstract = {Erythropoietin enhances oxygen delivery and reduces hypoxia-induced cell death, but its pro-thrombotic activity is problematic for use of erythropoietin in treating hypoxia. We constructed a fusion protein that stimulates red blood cell production and neuroprotection without triggering platelet production, a marker for thrombosis. The protein consists of an anti-glycophorin A nanobody and an erythropoietin mutant (L108A). The mutation reduces activation of erythropoietin receptor homodimers that induce erythropoiesis and thrombosis, but maintains the tissue-protective signaling. The binding of the nanobody element to glycophorin A rescues homodimeric erythropoietin receptor activation on red blood cell precursors. In a cell proliferation assay, the fusion protein is active at 10−14 M, allowing an estimate of the number of receptor–ligand complexes needed for signaling. This fusion protein stimulates erythroid cell proliferation in vitro and in mice, and shows neuroprotective activity in vitro. Our erythropoietin fusion protein presents a novel molecule for treating hypoxia.}, author = {Lee, Jungmin and Vernet, Andyna and Gruber, Nathalie and Kready, Kasia M. and Burrill, Devin R. and Way, Jeffrey C. and Silver, Pamela A.}, issn = {1741-0134}, journal = {Protein Engineering, Design and Selection}, publisher = {Oxford University Press}, title = {{Rational engineering of an erythropoietin fusion protein to treat hypoxia}}, doi = {10.1093/protein/gzab025}, volume = {34}, year = {2021}, } @article{10366, author = {Heisenberg, Carl-Philipp J and Lennon, Ana Maria and Mayor, Roberto and Salbreux, Guillaume}, issn = {2667-2901}, journal = {Cells and Development}, number = {12}, publisher = {Elsevier}, title = {{Special rebranding issue: “Quantitative cell and developmental biology”}}, doi = {10.1016/j.cdev.2021.203758}, volume = {168}, year = {2021}, } @article{10402, abstract = {Branching morphogenesis governs the formation of many organs such as lung, kidney, and the neurovascular system. Many studies have explored system-specific molecular and cellular regulatory mechanisms, as well as self-organizing rules underlying branching morphogenesis. However, in addition to local cues, branched tissue growth can also be influenced by global guidance. Here, we develop a theoretical framework for a stochastic self-organized branching process in the presence of external cues. Combining analytical theory with numerical simulations, we predict differential signatures of global vs. local regulatory mechanisms on the branching pattern, such as angle distributions, domain size, and space-filling efficiency. We find that branch alignment follows a generic scaling law determined by the strength of global guidance, while local interactions influence the tissue density but not its overall territory. Finally, using zebrafish innervation as a model system, we test these key features of the model experimentally. Our work thus provides quantitative predictions to disentangle the role of different types of cues in shaping branched structures across scales.}, author = {Ucar, Mehmet C and Kamenev, Dmitrii and Sunadome, Kazunori and Fachet, Dominik C and Lallemend, Francois and Adameyko, Igor and Hadjab, Saida and Hannezo, Edouard B}, issn = {2041-1723}, journal = {Nature Communications}, publisher = {Springer Nature}, title = {{Theory of branching morphogenesis by local interactions and global guidance}}, doi = {10.1038/s41467-021-27135-5}, volume = {12}, year = {2021}, } @inproceedings{10407, abstract = {Digital hardware Trojans are integrated circuits whose implementation differ from the specification in an arbitrary and malicious way. For example, the circuit can differ from its specified input/output behavior after some fixed number of queries (known as “time bombs”) or on some particular input (known as “cheat codes”). To detect such Trojans, countermeasures using multiparty computation (MPC) or verifiable computation (VC) have been proposed. On a high level, to realize a circuit with specification F one has more sophisticated circuits F⋄ manufactured (where F⋄ specifies a MPC or VC of F ), and then embeds these F⋄ ’s into a master circuit which must be trusted but is relatively simple compared to F . Those solutions impose a significant overhead as F⋄ is much more complex than F , also the master circuits are not exactly trivial. In this work, we show that in restricted settings, where F has no evolving state and is queried on independent inputs, we can achieve a relaxed security notion using very simple constructions. In particular, we do not change the specification of the circuit at all (i.e., F=F⋄ ). Moreover the master circuit basically just queries a subset of its manufactured circuits and checks if they’re all the same. The security we achieve guarantees that, if the manufactured circuits are initially tested on up to T inputs, the master circuit will catch Trojans that try to deviate on significantly more than a 1/T fraction of the inputs. This bound is optimal for the type of construction considered, and we provably achieve it using a construction where 12 instantiations of F need to be embedded into the master. We also discuss an extremely simple construction with just 2 instantiations for which we conjecture that it already achieves the optimal bound.}, author = {Chakraborty, Suvradip and Dziembowski, Stefan and Gałązka, Małgorzata and Lizurej, Tomasz and Pietrzak, Krzysztof Z and Yeo, Michelle X}, isbn = {9-783-0309-0452-4}, issn = {1611-3349}, location = {Raleigh, NC, United States}, pages = {397--428}, publisher = {Springer Nature}, title = {{Trojan-resilience without cryptography}}, doi = {10.1007/978-3-030-90453-1_14}, volume = {13043}, year = {2021}, } @article{10403, abstract = {Synaptic transmission, connectivity, and dendritic morphology mature in parallel during brain development and are often disrupted in neurodevelopmental disorders. Yet how these changes influence the neuronal computations necessary for normal brain function are not well understood. To identify cellular mechanisms underlying the maturation of synaptic integration in interneurons, we combined patch-clamp recordings of excitatory inputs in mouse cerebellar stellate cells (SCs), three-dimensional reconstruction of SC morphology with excitatory synapse location, and biophysical modeling. We found that postnatal maturation of postsynaptic strength was homogeneously reduced along the somatodendritic axis, but dendritic integration was always sublinear. However, dendritic branching increased without changes in synapse density, leading to a substantial gain in distal inputs. Thus, changes in synapse distribution, rather than dendrite cable properties, are the dominant mechanism underlying the maturation of neuronal computation. These mechanisms favor the emergence of a spatially compartmentalized two-stage integration model promoting location-dependent integration within dendritic subunits.}, author = {Biane, Celia and Rückerl, Florian and Abrahamsson, Therese and Saint-Cloment, Cécile and Mariani, Jean and Shigemoto, Ryuichi and Digregorio, David A. and Sherrard, Rachel M. and Cathala, Laurence}, issn = {2050-084X}, journal = {eLife}, publisher = {eLife Sciences Publications}, title = {{Developmental emergence of two-stage nonlinear synaptic integration in cerebellar interneurons}}, doi = {10.7554/eLife.65954}, volume = {10}, year = {2021}, } @article{10401, abstract = {Theoretical and experimental studies of the interaction between spins and temperature are vital for the development of spin caloritronics, as they dictate the design of future devices. In this work, we propose a two-terminal cold-atom simulator to study that interaction. The proposed quantum simulator consists of strongly interacting atoms that occupy two temperature reservoirs connected by a one-dimensional link. First, we argue that the dynamics in the link can be described using an inhomogeneous Heisenberg spin chain whose couplings are defined by the local temperature. Second, we show the existence of a spin current in a system with a temperature difference by studying the dynamics that follows the spin-flip of an atom in the link. A temperature gradient accelerates the impurity in one direction more than in the other, leading to an overall spin current similar to the spin Seebeck effect.}, author = {Barfknecht, Rafael E. and Foerster, Angela and Zinner, Nikolaj T. and Volosniev, Artem}, issn = {23993650}, journal = {Communications Physics}, number = {1}, publisher = {Springer Nature}, title = {{Generation of spin currents by a temperature gradient in a two-terminal device}}, doi = {10.1038/s42005-021-00753-7}, volume = {4}, year = {2021}, } @article{10404, abstract = {While convolutional neural networks (CNNs) have found wide adoption as state-of-the-art models for image-related tasks, their predictions are often highly sensitive to small input perturbations, which the human vision is robust against. This paper presents Perturber, a web-based application that allows users to instantaneously explore how CNN activations and predictions evolve when a 3D input scene is interactively perturbed. Perturber offers a large variety of scene modifications, such as camera controls, lighting and shading effects, background modifications, object morphing, as well as adversarial attacks, to facilitate the discovery of potential vulnerabilities. Fine-tuned model versions can be directly compared for qualitative evaluation of their robustness. Case studies with machine learning experts have shown that Perturber helps users to quickly generate hypotheses about model vulnerabilities and to qualitatively compare model behavior. Using quantitative analyses, we could replicate users’ insights with other CNN architectures and input images, yielding new insights about the vulnerability of adversarially trained models.}, author = {Sietzen, Stefan and Lechner, Mathias and Borowski, Judy and Hasani, Ramin and Waldner, Manuela}, issn = {1467-8659}, journal = {Computer Graphics Forum}, number = {7}, pages = {253--264}, publisher = {Wiley}, title = {{Interactive analysis of CNN robustness}}, doi = {10.1111/cgf.14418}, volume = {40}, year = {2021}, } @article{10406, abstract = {Multicellular organisms develop complex shapes from much simpler, single-celled zygotes through a process commonly called morphogenesis. Morphogenesis involves an interplay between several factors, ranging from the gene regulatory networks determining cell fate and differentiation to the mechanical processes underlying cell and tissue shape changes. Thus, the study of morphogenesis has historically been based on multidisciplinary approaches at the interface of biology with physics and mathematics. Recent technological advances have further improved our ability to study morphogenesis by bridging the gap between the genetic and biophysical factors through the development of new tools for visualizing, analyzing, and perturbing these factors and their biochemical intermediaries. Here, we review how a combination of genetic, microscopic, biophysical, and biochemical approaches has aided our attempts to understand morphogenesis and discuss potential approaches that may be beneficial to such an inquiry in the future.}, author = {Mishra, Nikhil and Heisenberg, Carl-Philipp J}, issn = {1545-2948}, journal = {Annual Review of Genetics}, keywords = {morphogenesis, forward genetics, high-resolution microscopy, biophysics, biochemistry, patterning}, pages = {209--233}, publisher = {Annual Reviews}, title = {{Dissecting organismal morphogenesis by bridging genetics and biophysics}}, doi = {10.1146/annurev-genet-071819-103748}, volume = {55}, year = {2021}, } @misc{13058, abstract = {The zip file includes source data used in the main text of the manuscript "Theory of branching morphogenesis by local interactions and global guidance", as well as a representative Jupyter notebook to reproduce the main figures. A sample script for the simulations of branching and annihilating random walks is also included (Sample_script_for_simulations_of_BARWs.ipynb) to generate exemplary branched networks under external guidance. A detailed description of the simulation setup is provided in the supplementary information of the manuscipt.}, author = {Ucar, Mehmet C}, publisher = {Zenodo}, title = {{Source data for the manuscript "Theory of branching morphogenesis by local interactions and global guidance"}}, doi = {10.5281/ZENODO.5257160}, year = {2021}, } @inproceedings{10408, abstract = {Key trees are often the best solution in terms of transmission cost and storage requirements for managing keys in a setting where a group needs to share a secret key, while being able to efficiently rotate the key material of users (in order to recover from a potential compromise, or to add or remove users). Applications include multicast encryption protocols like LKH (Logical Key Hierarchies) or group messaging like the current IETF proposal TreeKEM. A key tree is a (typically balanced) binary tree, where each node is identified with a key: leaf nodes hold users’ secret keys while the root is the shared group key. For a group of size N, each user just holds log(N) keys (the keys on the path from its leaf to the root) and its entire key material can be rotated by broadcasting 2log(N) ciphertexts (encrypting each fresh key on the path under the keys of its parents). In this work we consider the natural setting where we have many groups with partially overlapping sets of users, and ask if we can find solutions where the cost of rotating a key is better than in the trivial one where we have a separate key tree for each group. We show that in an asymptotic setting (where the number m of groups is fixed while the number N of users grows) there exist more general key graphs whose cost converges to the cost of a single group, thus saving a factor linear in the number of groups over the trivial solution. As our asymptotic “solution” converges very slowly and performs poorly on concrete examples, we propose an algorithm that uses a natural heuristic to compute a key graph for any given group structure. Our algorithm combines two greedy algorithms, and is thus very efficient: it first converts the group structure into a “lattice graph”, which is then turned into a key graph by repeatedly applying the algorithm for constructing a Huffman code. To better understand how far our proposal is from an optimal solution, we prove lower bounds on the update cost of continuous group-key agreement and multicast encryption in a symbolic model admitting (asymmetric) encryption, pseudorandom generators, and secret sharing as building blocks.}, author = {Alwen, Joel F and Auerbach, Benedikt and Baig, Mirza Ahad and Cueto Noval, Miguel and Klein, Karen and Pascual Perez, Guillermo and Pietrzak, Krzysztof Z and Walter, Michael}, booktitle = {19th International Conference}, isbn = {9-783-0309-0455-5}, issn = {1611-3349}, location = {Raleigh, NC, United States}, pages = {222--253}, publisher = {Springer Nature}, title = {{Grafting key trees: Efficient key management for overlapping groups}}, doi = {10.1007/978-3-030-90456-2_8}, volume = {13044}, year = {2021}, } @article{10527, abstract = {We show that in a two-dimensional electron gas with an annular Fermi surface, long-range Coulomb interactions can lead to unconventional superconductivity by the Kohn-Luttinger mechanism. Superconductivity is strongly enhanced when the inner and outer Fermi surfaces are close to each other. The most prevalent state has chiral p-wave symmetry, but d-wave and extended s-wave pairing are also possible. We discuss these results in the context of rhombohedral trilayer graphene, where superconductivity was recently discovered in regimes where the normal state has an annular Fermi surface. Using realistic parameters, our mechanism can account for the order of magnitude of Tc, as well as its trends as a function of electron density and perpendicular displacement field. Moreover, it naturally explains some of the outstanding puzzles in this material, that include the weak temperature dependence of the resistivity above Tc, and the proximity of spin singlet superconductivity to the ferromagnetic phase.}, author = {Ghazaryan, Areg and Holder, Tobias and Serbyn, Maksym and Berg, Erez}, issn = {1079-7114}, journal = {Physical Review Letters}, keywords = {general physics and astronomy}, number = {24}, publisher = {American Physical Society}, title = {{Unconventional superconductivity in systems with annular Fermi surfaces: Application to rhombohedral trilayer graphene}}, doi = {10.1103/physrevlett.127.247001}, volume = {127}, year = {2021}, } @article{10534, abstract = {For many years, fullerene derivatives have been the main n-type material of organic electronics and optoelectronics. Recently, fullerene derivatives functionalized with ethylene glycol (EG) side chains have been showing important properties such as enhanced dielectric constants, facile doping and enhanced self-assembly capabilities. Here, we have prepared field-effect transistors using a series of these fullerene derivatives equipped with EG side chains of different lengths. Transport data show the beneficial effect of increasing the EG side chain. In order to understand the material properties, full structural determination of these fullerene derivatives has been achieved by coupling the X-ray data with molecular dynamics (MD) simulations. The increase in transport properties is paired with the formation of extended layered structures, efficient molecular packing and an increase in the crystallite alignment. The layer-like structure is composed of conducting layers, containing of closely packed C60 balls approaching the inter-distance of 1 nm, that are separated by well-defined EG layers, where the EG chains are rather splayed with the chain direction almost perpendicular to the layer normal. Such a layered structure appears highly ordered and highly aligned with the C60 planes oriented parallel to the substrate in the thin film configuration. The order inside the thin film increases with the EG chain length, allowing the systems to achieve mobilities as high as 0.053 cm2 V−1 s−1. Our work elucidates the structure of these interesting semiconducting organic molecules and shows that the synergistic use of X-ray structural analysis and MD simulations is a powerful tool to identify the structure of thin organic films for optoelectronic applications.}, author = {Dong, Jingjin and Sami, Selim and Balazs, Daniel and Alessandri, Riccardo and Jahani, Fatimeh and Qiu, Li and Marrink, Siewert J. and Havenith, Remco W.A. and Hummelen, Jan C. and Loi, Maria A. and Portale, Giuseppe}, issn = {2050-7526}, journal = {Journal of Materials Chemistry C}, number = {45}, pages = {16217--16225}, publisher = {Royal Society of Chemistry}, title = {{Fullerene derivatives with oligoethylene-glycol side chains: An investigation on the origin of their outstanding transport properties}}, doi = {10.1039/d1tc02753k}, volume = {9}, year = {2021}, } @article{10533, abstract = {Flowering plants utilize small RNA molecules to guide DNA methyltransferases to genomic sequences. This RNA-directed DNA methylation (RdDM) pathway preferentially targets euchromatic transposable elements. However, RdDM is thought to be recruited by methylation of histone H3 at lysine 9 (H3K9me), a hallmark of heterochromatin. How RdDM is targeted to euchromatin despite an affinity for H3K9me is unclear. Here we show that loss of histone H1 enhances heterochromatic RdDM, preferentially at nucleosome linker DNA. Surprisingly, this does not require SHH1, the RdDM component that binds H3K9me. Furthermore, H3K9me is dispensable for RdDM, as is CG DNA methylation. Instead, we find that non-CG methylation is specifically associated with small RNA biogenesis, and without H1 small RNA production quantitatively expands to non-CG methylated loci. Our results demonstrate that H1 enforces the separation of euchromatic and heterochromatic DNA methylation pathways by excluding the small RNA-generating branch of RdDM from non-CG methylated heterochromatin.}, author = {Choi, Jaemyung and Lyons, David B and Zilberman, Daniel}, issn = {2050-084X}, journal = {eLife}, keywords = {genetics and molecular biology}, publisher = {eLife Sciences Publications}, title = {{Histone H1 prevents non-CG methylation-mediated small RNA biogenesis in Arabidopsis heterochromatin}}, doi = {10.7554/elife.72676}, volume = {10}, year = {2021}, } @article{10536, abstract = {TGFβ overexpression is commonly detected in cancer patients and correlates with poor prognosis and metastasis. Cancer progression is often associated with an enhanced recruitment of myeloid-derived cells to the tumor microenvironment. Here we show that functional TGFβ-signaling in myeloid cells is required for metastasis to the lungs and the liver. Myeloid-specific deletion of Tgfbr2 resulted in reduced spontaneous lung metastasis, which was associated with a reduction of proinflammatory cytokines in the metastatic microenvironment. Notably, CD8+ T cell depletion in myeloid-specific Tgfbr2-deficient mice rescued lung metastasis. Myeloid-specific Tgfbr2-deficiency resulted in reduced liver metastasis with an almost complete absence of myeloid cells within metastatic foci. On contrary, an accumulation of Tgfβ-responsive myeloid cells was associated with an increased recruitment of monocytes and granulocytes and higher proinflammatory cytokine levels in control mice. Monocytic cells isolated from metastatic livers of Tgfbr2-deficient mice showed increased polarization towards the M1 phenotype, Tnfα and Il-1β expression, reduced levels of M2 markers and reduced production of chemokines responsible for myeloid-cell recruitment. No significant differences in Tgfβ levels were observed at metastatic sites of any model. These data demonstrate that Tgfβ signaling in monocytic myeloid cells suppresses CD8+ T cell activity during lung metastasis, while these cells actively contribute to tumor growth during liver metastasis. Thus, myeloid cells modulate metastasis through different mechanisms in a tissue-specific manner.}, author = {Stefanescu, Cristina and Van Gogh, Merel and Roblek, Marko and Heikenwalder, Mathias and Borsig, Lubor}, issn = {2234-943X}, journal = {Frontiers in Oncology}, publisher = {Frontiers}, title = {{TGFβ signaling in myeloid cells promotes lung and liver metastasis through different mechanisms}}, doi = {10.3389/fonc.2021.765151}, volume = {11}, year = {2021}, } @article{10537, abstract = {We consider the quantum many-body evolution of a homogeneous Fermi gas in three dimensions in the coupled semiclassical and mean-field scaling regime. We study a class of initial data describing collective particle–hole pair excitations on the Fermi ball. Using a rigorous version of approximate bosonization, we prove that the many-body evolution can be approximated in Fock space norm by a quasi-free bosonic evolution of the collective particle–hole excitations.}, author = {Benedikter, Niels P and Nam, Phan Thành and Porta, Marcello and Schlein, Benjamin and Seiringer, Robert}, issn = {1424-0637}, journal = {Annales Henri Poincaré}, publisher = {Springer Nature}, title = {{Bosonization of fermionic many-body dynamics}}, doi = {10.1007/s00023-021-01136-y}, year = {2021}, } @article{10549, abstract = {We derive optimal-order homogenization rates for random nonlinear elliptic PDEs with monotone nonlinearity in the uniformly elliptic case. More precisely, for a random monotone operator on \mathbb {R}^d with stationary law (that is spatially homogeneous statistics) and fast decay of correlations on scales larger than the microscale \varepsilon >0, we establish homogenization error estimates of the order \varepsilon in case d\geqq 3, and of the order \varepsilon |\log \varepsilon |^{1/2} in case d=2. Previous results in nonlinear stochastic homogenization have been limited to a small algebraic rate of convergence \varepsilon ^\delta . We also establish error estimates for the approximation of the homogenized operator by the method of representative volumes of the order (L/\varepsilon )^{-d/2} for a representative volume of size L. Our results also hold in the case of systems for which a (small-scale) C^{1,\alpha } regularity theory is available.}, author = {Fischer, Julian L and Neukamm, Stefan}, issn = {1432-0673}, journal = {Archive for Rational Mechanics and Analysis}, keywords = {Mechanical Engineering, Mathematics (miscellaneous), Analysis}, number = {1}, pages = {343--452}, publisher = {Springer Nature}, title = {{Optimal homogenization rates in stochastic homogenization of nonlinear uniformly elliptic equations and systems}}, doi = {10.1007/s00205-021-01686-9}, volume = {242}, year = {2021}, } @inproceedings{10409, abstract = {We show that Yao’s garbling scheme is adaptively indistinguishable for the class of Boolean circuits of size S and treewidth w with only a SO(w) loss in security. For instance, circuits with constant treewidth are as a result adaptively indistinguishable with only a polynomial loss. This (partially) complements a negative result of Applebaum et al. (Crypto 2013), which showed (assuming one-way functions) that Yao’s garbling scheme cannot be adaptively simulatable. As main technical contributions, we introduce a new pebble game that abstracts out our security reduction and then present a pebbling strategy for this game where the number of pebbles used is roughly O(δwlog(S)) , δ being the fan-out of the circuit. The design of the strategy relies on separators, a graph-theoretic notion with connections to circuit complexity. with only a SO(w) loss in security. For instance, circuits with constant treewidth are as a result adaptively indistinguishable with only a polynomial loss. This (partially) complements a negative result of Applebaum et al. (Crypto 2013), which showed (assuming one-way functions) that Yao’s garbling scheme cannot be adaptively simulatable. As main technical contributions, we introduce a new pebble game that abstracts out our security reduction and then present a pebbling strategy for this game where the number of pebbles used is roughly O(δwlog(S)) , δ being the fan-out of the circuit. The design of the strategy relies on separators, a graph-theoretic notion with connections to circuit complexity.}, author = {Kamath Hosdurg, Chethan and Klein, Karen and Pietrzak, Krzysztof Z}, booktitle = {19th International Conference}, isbn = {9-783-0309-0452-4}, issn = {1611-3349}, location = {Raleigh, NC, United States}, pages = {486--517}, publisher = {Springer Nature}, title = {{On treewidth, separators and Yao’s garbling}}, doi = {10.1007/978-3-030-90453-1_17}, volume = {13043 }, year = {2021}, } @article{10545, abstract = {Classical models with complex energy landscapes represent a perspective avenue for the near-term application of quantum simulators. Until now, many theoretical works studied the performance of quantum algorithms for models with a unique ground state. However, when the classical problem is in a so-called clustering phase, the ground state manifold is highly degenerate. As an example, we consider a 3-XORSAT model defined on simple hypergraphs. The degeneracy of classical ground state manifold translates into the emergence of an extensive number of Z2 symmetries, which remain intact even in the presence of a quantum transverse magnetic field. We establish a general duality approach that restricts the quantum problem to a given sector of conserved Z2 charges and use it to study how the outcome of the quantum adiabatic algorithm depends on the hypergraph geometry. We show that the tree hypergraph which corresponds to a classically solvable instance of the 3-XORSAT problem features a constant gap, whereas the closed hypergraph encounters a second-order phase transition with a gap vanishing as a power-law in the problem size. The duality developed in this work provides a practical tool for studies of quantum models with classically degenerate energy manifold and reveals potential connections between glasses and gauge theories.}, author = {Medina Ramos, Raimel A and Serbyn, Maksym}, issn = {2469-9934}, journal = {Physical Review A}, number = {6}, publisher = {American Physical Society}, title = {{Duality approach to quantum annealing of the 3-variable exclusive-or satisfiability problem (3-XORSAT)}}, doi = {10.1103/physreva.104.062423}, volume = {104}, year = {2021}, } @inproceedings{10554, abstract = {We present DAG-Rider, the first asynchronous Byzantine Atomic Broadcast protocol that achieves optimal resilience, optimal amortized communication complexity, and optimal time complexity. DAG-Rider is post-quantum safe and ensures that all values proposed by correct processes eventually get delivered. We construct DAG-Rider in two layers: In the first layer, processes reliably broadcast their proposals and build a structured Directed Acyclic Graph (DAG) of the communication among them. In the second layer, processes locally observe their DAGs and totally order all proposals with no extra communication.}, author = {Keidar, Idit and Kokoris Kogias, Eleftherios and Naor, Oded and Spiegelman, Alexander}, booktitle = {Proceedings of the 2021 ACM Symposium on Principles of Distributed Computing}, isbn = {978-1-4503-8548-0}, location = {Virtual, Italy}, pages = {165--175}, publisher = {Association for Computing Machinery}, title = {{All You Need is DAG}}, doi = {10.1145/3465084.3467905}, year = {2021}, }