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Towards Practical Oblivious RAM
We take an important step forward in making Oblivious RAM (O-RAM) practical.
We propose an O-RAM construction achieving an amortized overhead of 20X-35X
(for an O-RAM roughly 1 terabyte in size), about 63 times faster than the best
existing scheme. On the theoretic front, we propose a fundamentally novel
technique for constructing Oblivious RAMs: specifically, we partition a bigger
O-RAM into smaller O-RAMs, and employ a background eviction technique to
obliviously evict blocks from the client-side cache into a randomly assigned
server-side partition. This novel technique is the key to achieving the gains
in practical performance
Plasmon geometric phase and plasmon Hall shift
The collective plasmonic modes of a metal comprise a pattern of charge
density and tightly-bound electric fields that oscillate in lock-step to yield
enhanced light-matter interaction. Here we show that metals with non-zero Hall
conductivity host plasmons with a fine internal structure: they are
characterized by a current density configuration that sharply departs from that
of ordinary zero Hall conductivity metals. This non-trivial internal structure
dramatically enriches the dynamics of plasmon propagation, enabling plasmon
wavepackets to acquire geometric phases as they scatter. Strikingly, at
boundaries these phases accumulate allowing plasmon waves that reflect off to
experience a non-reciprocal parallel shift along the boundary displacing the
incident and reflected plasmon trajectories. This plasmon Hall shift, tunable
by Hall conductivity as well as plasmon wavelength, displays the chirality of
the plasmon's current distribution and can be probed by near-field photonics
techniques. Anomalous plasmon dynamics provide a real-space window into the
inner structure of plasmon bands, as well as new means for directing plasmonic
beams
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