1,065 research outputs found
Delegating Quantum Computation in the Quantum Random Oracle Model
A delegation scheme allows a computationally weak client to use a server's
resources to help it evaluate a complex circuit without leaking any information
about the input (other than its length) to the server. In this paper, we
consider delegation schemes for quantum circuits, where we try to minimize the
quantum operations needed by the client. We construct a new scheme for
delegating a large circuit family, which we call "C+P circuits". "C+P" circuits
are the circuits composed of Toffoli gates and diagonal gates. Our scheme is
non-interactive, requires very little quantum computation from the client
(proportional to input length but independent of the circuit size), and can be
proved secure in the quantum random oracle model, without relying on additional
assumptions, such as the existence of fully homomorphic encryption. In practice
the random oracle can be replaced by an appropriate hash function or block
cipher, for example, SHA-3, AES.
This protocol allows a client to delegate the most expensive part of some
quantum algorithms, for example, Shor's algorithm. The previous protocols that
are powerful enough to delegate Shor's algorithm require either many rounds of
interactions or the existence of FHE. The protocol requires asymptotically
fewer quantum gates on the client side compared to running Shor's algorithm
locally.
To hide the inputs, our scheme uses an encoding that maps one input qubit to
multiple qubits. We then provide a novel generalization of classical garbled
circuits ("reversible garbled circuits") to allow the computation of Toffoli
circuits on this encoding. We also give a technique that can support the
computation of phase gates on this encoding.
To prove the security of this protocol, we study key dependent message(KDM)
security in the quantum random oracle model. KDM security was not previously
studied in quantum settings.Comment: 41 pages, 1 figures. Update to be consistent with the proceeding
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DC-SIGN–mediated Infectious Synapse Formation Enhances X4 HIV-1 Transmission from Dendritic Cells to T Cells
Dendritic cells (DCs) are essential for the early events of human immunodeficiency virus (HIV) infection. Model systems of HIV sexual transmission have shown that DCs expressing the DC-specific C-type lectin DC-SIGN capture and internalize HIV at mucosal surfaces and efficiently transfer HIV to CD4+ T cells in lymph nodes, where viral replication occurs. Upon DC–T cell clustering, internalized HIV accumulates on the DC side at the contact zone (infectious synapse), between DCs and T cells, whereas HIV receptors and coreceptors are enriched on the T cell side. Viral concentration at the infectious synapse may explain, at least in part, why DC transmission of HIV to T cells is so efficient
Strongly anisotropic spin relaxation in graphene/transition metal dichalcogenide heterostructures at room temperature
Graphene has emerged as the foremost material for future two-dimensional
spintronics due to its tuneable electronic properties. In graphene, spin
information can be transported over long distances and, in principle, be
manipulated by using magnetic correlations or large spin-orbit coupling (SOC)
induced by proximity effects. In particular, a dramatic SOC enhancement has
been predicted when interfacing graphene with a semiconducting transition metal
dechalcogenide, such as tungsten disulphide (WS). Signatures of such an
enhancement have recently been reported but the nature of the spin relaxation
in these systems remains unknown. Here, we unambiguously demonstrate
anisotropic spin dynamics in bilayer heterostructures comprising graphene and
WS. By using out-of-plane spin precession, we show that the spin lifetime
is largest when the spins point out of the graphene plane. Moreover, we observe
that the spin lifetime varies over one order of magnitude depending on the spin
orientation, indicating that the strong spin-valley coupling in WS is
imprinted in the bilayer and felt by the propagating spins. These findings
provide a rich platform to explore coupled spin-valley phenomena and offer
novel spin manipulation strategies based on spin relaxation anisotropy in
two-dimensional materials
A novel role for the root cap in phosphate uptake and homeostasis
The root cap has a fundamental role in sensing environmental cues as well as regulating root growth via altered meristem activity. Despite this well-established role in the control of developmental processes in roots, the root cap's function in nutrition remains obscure. Here, we uncover its role in phosphate nutrition by targeted cellular inactivation or phosphate transport complementation in Arabidopsis, using a transactivation strategy with an innovative high-resolution real-time P-33 imaging technique. Remarkably, the diminutive size of the root cap cells at the root-to-soil exchange surface accounts for a significant amount of the total seedling phosphate uptake (approximately 20%). This level of Pi absorption is sufficient for shoot biomass production (up to a 180% gain in soil), as well as repression of Pi starvation-induced genes. These results extend our understanding of this important tissue from its previously described roles in environmental perception to novel functions in mineral nutrition and homeostasis control
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Rapid attribution of the August 2016 flood-inducing extreme precipitation in south Louisiana to climate change
A stationary low pressure system and elevated levels of precipitable water
provided a nearly continuous source of precipitation over Louisiana, United
States (US), starting around 10 August 2016. Precipitation was heaviest in
the region broadly encompassing the city of Baton Rouge, with a 3-day maximum
found at a station in Livingston, LA (east of Baton Rouge), from 12 to 14 August 2016 (648.3 mm, 25.5 inches). The intense precipitation was followed
by inland flash flooding and river flooding and in subsequent days produced
additional backwater flooding. On 16 August, Louisiana officials reported
that 30 000 people had been rescued, nearly 10 600 people had slept in
shelters on the night of 14 August and at least 60 600 homes had been
impacted to varying degrees. As of 17 August, the floods were reported to
have killed at least 13 people. As the disaster was unfolding, the Red
Cross called the flooding the worst natural disaster in the US since Super
Storm Sandy made landfall in New Jersey on 24 October 2012. Before the
floodwaters had receded, the media began questioning whether this extreme
event was caused by anthropogenic climate change. To provide the necessary
analysis to understand the potential role of anthropogenic climate change, a
rapid attribution analysis was launched in real time using the best readily
available observational data and high-resolution global climate model
simulations.
The objective of this study is to show the possibility of performing rapid
attribution studies when both observational and model data and analysis
methods are readily available upon the start. It is the authors' aspiration
that the results be used to guide further studies of the devastating
precipitation and flooding event. Here, we present a first estimate of how
anthropogenic climate change has affected the likelihood of a comparable
extreme precipitation event in the central US Gulf Coast. While the
flooding event of interest triggering this study occurred in south Louisiana,
for the purposes of our analysis, we have defined an extreme precipitation
event by taking the spatial maximum of annual 3-day inland maximum
precipitation over the region of 29–31° N, 85–95° W, which
we refer to as the central US Gulf Coast. Using observational data, we find
that the observed local return time of the 12–14 August precipitation event
in 2016 is about 550 years (95 % confidence interval (CI): 450–1450).
The probability for an event like this to happen anywhere in the region is
presently 1 in 30 years (CI 11–110). We estimate that these probabilities
and the intensity of extreme precipitation events of this return time have
increased since 1900. A central US Gulf Coast extreme precipitation event
has effectively become more likely in 2016 than it was in 1900. The global
climate models tell a similar story; in the most accurate analyses, the
regional probability of 3-day extreme precipitation increases by more than a
factor of 1.4 due to anthropogenic climate change. The magnitude of the shift in
probabilities is greater in the 25 km (higher-resolution) climate model than
in the 50 km model. The evidence for a relation to El Niño half a year
earlier is equivocal, with some analyses showing a positive connection and
others none
Geographical interdependence, international trade and economic dynamics: the Chinese and German solar energy industries
The trajectories of the German and Chinese photovoltaic industries differ significantly yet are strongly interdependent. Germany has seen a rapid growth in market demand and a strong increase in production, especially in the less developed eastern half of the country. Chinese growth has been export driven. These contrasting trajectories reflect the roles of market creation, investment and credit and the drivers of innovation and competitiveness. Consequent differences in competiveness have generated major trade disputes
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