1,721,118 research outputs found
Qualitative properties and construction of solutions to some semilinear elliptic PDEs
Full text linkThis thesis is devoted to the study of elliptic equations. On the one hand, we study some qualitative properties, such as symmetry of solutions, on the other hand we explicitly construct some solutions vanishing near some fixed manifold. The main techniques are the moving planes method, in order to investigate the qualitative properties and the Lyapunov-Schmidt reduction
Optimal persistent currents for interacting bosons on a ring with a gauge field
Full text linkWe study persistent currents for interacting one-dimensional bosons on a tight ring trap, subjected to a rotating barrier potential, which induces an artificial U(1) gauge field. We show that, at intermediate interactions, the persistent current response is maximal, due to a subtle interplay of effects due to the barrier, the interaction, and quantum fluctuations. These results are relevant for ongoing experiments with ultracold atomic gases on mesoscopic rings. © 2014 American Physical Society
Demo: TLSAssistant v2: A Modular and Extensible Framework for Securing TLS
No full textTo grasp the security implications of the various TLS configuration options, system administrators and app developers must be familiar with a wide range of concepts, including cryptography. To assist users in this task, we propose TLSAssistant- a modular and extensible framework designed to streamline the discovery and mitigation of potential vulnerabilities in TLS deployments. This demo will focus on two of the four available analysis types
Quantum memories with zero-energy Majorana modes and experimental constraints
Full text linkIn this work we address the problem of realizing a reliable quantum memory based on zero-energy Majorana modes in the presence of experimental constraints on the operations aimed at recovering the information. In particular, we characterize the best recovery operation acting only on the zero-energy Majorana modes and the memory fidelity that can be therewith achieved. In order to understand the effect of such restriction, we discuss two examples of noise models acting on the topological system and compare the amount of information that can be recovered by accessing either the whole system, or the zero modes only, with particular attention to the scaling with the size of the system and the energy gap. We explicitly discuss the case of a thermal bosonic environment inducing a parity-preserving Markovian dynamics in which the memory fidelity achievable via a read-out of the zero modes decays exponentially in time, independent from system size. We argue, however, that even in the presence of said experimental limitations, the Hamiltonian gap is still beneficial to the storage of information
Perturbative approach to continuous-time quantum error correction
No full textWe present a discussion of the continuous-time quantum error correction introduced by J. P. Paz and W. H. Zurek [Proc. R. Soc. A 454, 355 (1998)]. We study the general Lindbladian which describes the effects of both noise and error correction in the weak-noise (or strong-correction) regime through a perturbative expansion. We use this tool to derive quantitative aspects of the continuous-time dynamics both in general and through two illustrative examples: the three-qubit and five-qubit stabilizer codes, which can be independently solved by analytical and numerical methods and then used as benchmarks for the perturbative approach. The perturbatively accessible time frame features a short initial transient in which error correction is ineffective, followed by a slow decay of the information content consistent with the known facts about discrete-time error correction in the limit of fast operations. This behavior is explained in the two case studies through a geometric description of the continuous transformation of the state space induced by the combined action of noise and error correction
A Modular and Extensible Framework for Securing TLS
No full textWhile being both extremely powerful and popular, TLS is a protocol that is hard to securely deploy. On the one hand, system administrators are required to grasp several security concepts to fully understand the impact of each option and avoid misconfigurations. On the other hand, app developers should use cryptographic libraries in a secure way avoiding dangerous default settings or other subtleties (e.g., padding or modes of operations). To help secure TLS, we propose a modular framework, extensible with new features and capable of streamlining the mitigation process of known and newly discovered TLS attacks even for non-expert users
A Modular and Extensible Framework for Securing TLS
No full textWhile being both extremely powerful and popular, TLS is a protocol that is hard to securely deploy. On the one hand, system administrators are required to grasp several security concepts to fully understand the impact of each option and avoid misconfigurations. On the other hand, app developers should use cryptographic libraries in a secure way avoiding dangerous default settings or other subtleties (e.g., padding or modes of operations). To help secure TLS, we propose a modular framework, extensible with new features and capable of streamlining the mitigation process of known and newly discovered TLS attacks even for non-expert users
Simulation of time evolution with multiscale entanglement renormalization ansatz
Full text linkWe describe an algorithm to simulate time evolution using the multiscale entanglement renormalization ansatz and test it by studying a critical Ising chain with periodic boundary conditions and with up to L[approximate]106 quantum spins. The cost of a simulation, which scales as L log2(L), is reduced to log2(L) when the system is invariant under translations. By simulating an evolution in imaginary time, we compute the ground state of the system. The errors in the ground-state energy display no evident dependence on the system size. The algorithm can be extended to lattice systems in higher spatial dimensions
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