321 research outputs found
SplitBox: Toward Efficient Private Network Function Virtualization
This paper presents SplitBox, an efficient system for privacy-preserving processing of network functions that are outsourced as software processes to the cloud. Specifically, cloud providers processing the network functions do not learn the network policies instructing how the functions are to be processed. First, we propose an abstract model of a generic network function based on match-action pairs. We assume that this function is processed in a distributed manner by multiple honest-but-curious cloud service providers. Then, we introduce our SplitBox system for private network function virtualization and present a proof-of-concept implementation on FastClick, an extension of the Click modular router, using a firewall as a use case. Our experimental results achieve a throughput of over 2 Gbps with 1 kB-sized packets on average, traversing up to 60 firewall rules
Fast privacy-preserving network function outsourcing
In this paper, we present the design and implementation of SplitBox, a system for privacy-preserving processing of network functions outsourced to cloud middleboxes—i.e., without revealing the policies governing these functions. SplitBox is built to provide privacy for a generic network function that abstracts the functionality of a variety of network functions and associated policies, including firewalls, virtual LANs, network address translators (NATs), deep packet inspection, and load balancers. We present a scalable design aiming to provide high throughput and low latency, by distributing functionalities to a few virtual machines (VMs), while providing provably secure guarantees. We implement SplitBox inside FastClick, an extension of the Click modular router, using Intel's DPDK to handle packet I/O. We evaluate our prototype experimentally to find its bottlenecks and stress-test its different components, vis-à -vis two widely used network functions, i.e., firewall and VLAN tagging. Our evaluation shows that, on commodity hardware, SplitBox can process packets close to line rate (i.e., 8.9Gbps) with up to 50 traversed policies
Ultrafast optical nonlinearity in quasi-one-dimensional Mott-insulator
We report strong instantaneous photoinduced absorption (PA) in the
quasi-one-dimensional Mott insulator in the IR spectral
region. The observed PA is to an even-parity two-photon state that occurs
immediately above the absorption edge. Theoretical calculations based on a
two-band extended Hubbard model explains the experimental features and
indicates that the strong two-photon absorption is due to a very large
dipole-coupling between nearly degenerate one- and two-photon states. Room
temperature picosecond recovery of the optical transparency suggests the strong
potential of for all-optical switching.Comment: 10 pages, 4 figure
On Form Factors in nested Bethe Ansatz systems
We investigate form factors of local operators in the multi-component Quantum
Non-linear Schr\"odinger model, a prototype theory solvable by the so-called
nested Bethe Ansatz. We determine the analytic properties of the infinite
volume form factors using the coordinate Bethe Ansatz solution and we establish
a connection with the finite volume matrix elements. In the two-component
models we derive a set of recursion relations for the "magnonic form factors",
which are the matrix elements on the nested Bethe Ansatz states. In certain
simple cases (involving states with only one spin-impurity) we obtain explicit
solutions for the recursion relations.Comment: 34 pages, v2 (minor modifications
A theoretical investigation of the low lying electronic structure of poly(p-phenylene vinylene)
The two-state molecular orbital model of the one-dimensional phenyl-based
semiconductors is applied to poly(p-phenylene vinylene). The energies of the
low-lying excited states are calculated using the density matrix
renormalization group method. Calculations of both the exciton size and the
charge gap show that there are both Bu and Ag excitonic levels below the band
threshold. The energy of the 1Bu exciton extrapolates to 2.60 eV in the limit
of infinite polymers, while the energy of the 2Ag exciton extrapolates to 2.94
eV. The calculated binding energy of the 1Bu exciton is 0.9 eV for a 13
phenylene unit chain and 0.6 eV for an infinite polymer. This is expected to
decrease due to solvation effects. The lowest triplet state is calculated to be
at ca. 1.6 eV, with the triplet-triplet gap being ca. 1.6 eV. A comparison
between theory, and two-photon absorption and electroabsorption is made,
leading to a consistent picture of the essential states responsible for most of
the third-order nonlinear optical properties. An interpretation of the
experimental nonlinear optical spectroscopies suggests an energy difference of
ca. 0.4 eV between the vertical energy and ca. 0.8 eV between the relaxed
energy, of the 1Bu exciton and the band gap, respectively.Comment: LaTeX, 19 pages, 7 eps figures included using epsf. To appear in
Physical Review B, 199
Ultra-cold Polarized Fermi Gases
Recent experiments with ultra-cold atoms have demonstrated the possibility of
realizing experimentally fermionic superfluids with imbalanced spin
populations. We discuss how these developments have shed a new light on a half-
century old open problem in condensed matter physics, and raised new
interrogations of their own.Comment: 27 pages; 8 figures; Published in Report in Rep. Prog. Phys. 73
112401 (2010
Quantum flutter of supersonic particles in one-dimensional quantum liquids
The non-equilibrium dynamics of strongly correlated many-body systems
exhibits some of the most puzzling phenomena and challenging problems in
condensed matter physics. Here we report on essentially exact results on the
time evolution of an impurity injected at a finite velocity into a
one-dimensional quantum liquid. We provide the first quantitative study of the
formation of the correlation hole around a particle in a strongly coupled
many-body quantum system, and find that the resulting correlated state does not
come to a complete stop but reaches a steady state which propagates at a finite
velocity. We also uncover a novel physical phenomenon when the impurity is
injected at supersonic velocities: the correlation hole undergoes long-lived
coherent oscillations around the impurity, an effect we call quantum flutter.
We provide a detailed understanding and an intuitive physical picture of these
intriguing discoveries, and propose an experimental setup where this physics
can be realized and probed directly.Comment: 13 pages, 9 figure
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