101 research outputs found
Quantum bit threads
We give a bit thread prescription that is equivalent to the quantum extremal
surface prescription for holographic entanglement entropy. Our proposal is
inspired by considerations of bit threads in doubly holographic models, and
equivalence is established by proving a generalisation of the Riemannian
max-flow min-cut theorem. We explore our proposal's properties and discuss ways
in which islands and spacetime are emergent phenomena from the quantum bit
thread perspective.Comment: 24 pages, 5 figures; v2: minor improvements made and new appendix
added; v3: version for publication with no significant change
A Compiler from Array Programs to Vectorized Homomorphic Encryption
Homomorphic encryption (HE) is a practical approach to secure computation
over encrypted data. However, writing programs with efficient HE
implementations remains the purview of experts. A difficult barrier for
programmability is that efficiency requires operations to be vectorized in
inobvious ways, forcing efficient HE programs to manipulate ciphertexts with
complex data layouts and to interleave computations with data movement
primitives.
We present Viaduct-HE, a compiler generates efficient vectorized HE programs.
Viaduct-HE can generate both the operations and complex data layouts required
for efficient HE programs. The source language of Viaduct-HE is array-oriented,
enabling the compiler to have a simple representation of possible vectorization
schedules. With such a representation, the compiler searches the space of
possible vectorization schedules and finds those with efficient data layouts.
After finding a vectorization schedule, Viaduct-HE further optimizes HE
programs through term rewriting. The compiler has extension points to customize
the exploration of vectorization schedules, to customize the cost model for HE
programs, and to add back ends for new HE libraries.
Our evaluation of the prototype Viaduct-HE compiler shows that it produces
efficient vectorized HE programs with sophisticated data layouts and
optimizations comparable to those designed by experts
Tunneling to Holographic Traversable Wormholes
We study nonperturbative effects of quantum gravity in a system consisting of
a coupled pair of holographic CFTs. The AdS/CFT system has three
possible ground states: two copies of empty AdS, a pair of extremal AdS black
holes, and an eternal AdS traversable wormhole. We give a recipe for
calculating transition rates via gravitational instantons and test it by
calculating the emission rate of radiation shells from a black hole. We
calculate the nucleation rate of a traversable wormhole between a pair of
AdS-RN black holes in the canonical and microcanonical ensembles. Our results
give predictions of nonpertubative quantum gravity that can be tested in a
holographic simulation.Comment: 65 pages, 2 figure
Tools of the Trade: An Ethnohistoric and Archaeological Investigation of Late Fort Ancient Bifacial Endscrapers
The arrival of Europeans to the New World forever changed the social and economic landscapes of Native Peoples who occupied the continents. Colonial institutions profited off the land and those who occupied it. One institution that exemplified this was the Fur Trade. Throughout the North and Northeast colonies, European nations acquired furs from a variety of mammals to meet the trans-Atlantic demand. To maximize profits in the New World many European colonizers turned to Native peoples to aid in their economic endeavors. Native Americans employed trade routes and knowledge of the land to their advantage in the new economic landscape.
In this IS, I illustrate the role that the Late Fort Ancient people played during the Fur Trade by investigating, the context bifacial endscrapers which appear to spike in usage during the period of (1450-1750 A.D). I evaluate ethnohistoric evidence to determine whether the Late Fort Ancient peoples may have been engaged in hide production work as a response to increasing European demand
A Tour of Gallifrey, a Language for Geodistributed Programming
Programming efficient distributed, concurrent systems requires new abstractions that go beyond traditional sequential programming. But programmers already have trouble getting sequential code right, so simplicity is essential. The core problem is that low-latency, high-availability access to data requires replication of mutable state. Keeping replicas fully consistent is expensive, so the question is how to expose asynchronously replicated objects to programmers in a way that allows them to reason simply about their code. We propose an answer to this question in our ongoing work designing a new language, Gallifrey, which provides orthogonal replication through _restrictions_ with _merge strategies_, _contingencies_ for conflicts arising from concurrency, and _branches_, a novel concurrency control construct inspired by version control, to contain provisional behavior
Spacetime as a quantum circuit
We propose that finite cutoff regions of holographic spacetimes represent
quantum circuits that map between boundary states at different times and
Wilsonian cutoffs, and that the complexity of those quantum circuits is given
by the gravitational action. The optimal circuit minimizes the gravitational
action. This is a generalization of both the "complexity equals volume"
conjecture to unoptimized circuits, and path integral optimization to finite
cutoffs. Using tools from holographic , we find that surfaces of
constant scalar curvature play a special role in optimizing quantum circuits.
We also find an interesting connection of our proposal to kinematic space, and
discuss possible circuit representations and gate counting interpretations of
the gravitational action.Comment: 26 pages, 2 figure
Viaduct: An Extensible, Optimizing Compiler for Secure Distributed Programs (Technical Report)
Modern distributed systems involve interactions between principals with limited trust, so cryptographic mechanisms are needed to protect confidentiality and integrity. At the same time, most developers lack the training to securely employ cryptography. We present Viaduct, a compiler that transforms high-level programs into secure, efficient distributed realizations. Viaduct\u27s source language allows developers to declaratively specify security policies by annotating their programs with information flow labels. The compiler uses these labels to synthesize distributed programs that use cryptography efficiently while still defending the source-level security policy. The Viaduct approach is general, and can be easily extended with new security mechanisms.
Our implementation of the Viaduct compiler comes with an extensible runtime system that includes plug-in support for multiparty computation, commitments, and zero-knowledge proofs. We have evaluated the system on a set of benchmarks, and the results indicate that our approach is feasible and can use cryptography in efficient, nontrivial ways
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