2,124 research outputs found
Transport properties of dense deuterium-tritium plasmas
Consistent descriptions of the equation of states, and information about
transport coefficients of deuterium-tritium mixture are demonstrated through
quantum molecular dynamic (QMD) simulations (up to a density of 600 g/cm
and a temperature of eV). Diffusion coefficients and viscosity are
compared with one component plasma model in different regimes from the strong
coupled to the kinetic one. Electronic and radiative transport coefficients,
which are compared with models currently used in hydrodynamic simulations of
inertial confinement fusion, are evaluated up to 800 eV. The Lorentz number is
also discussed from the highly degenerate to the intermediate region.Comment: 4 pages, 3 figure
Differentiation between tuberculosis and leukemia in abdominal and pelvic lymph nodes: evaluation with contrast-enhanced multidetector computed tomography
PURPOSE: To compare the characteristics of tubercular vs. leukemic involvement of abdominopelvic lymph nodes using multidetector computed tomography (CT). MATERIALS AND METHODS: We retrospectively reviewed multidetector computed tomography features including lymph node size, shape, enhancement patterns, and anatomical distribution, in 106 consecutive patients with newly diagnosed, untreated tuberculosis (55 patients; 52%) or leukemia (51 patients; 48%). In patients with leukemia, 32 (62.7%) had chronic lymphocytic leukemia, and 19 (37.3%) had acute leukemias; of these, 10 (19.6%) had acute myeloid leukemia, and 9 (17.6%) had acute lymphocytic leukemia. RESULTS: The lower para-aortic (30.9% for tuberculosis, 63.2% for acute leukemias and 87.5% for chronic lymphocytic leukemia) and inguinal (9.1% for tuberculosis, 57.9% for acute leukemias and 53.1% for chronic lymphocytic leukemia) lymph nodes were involved more frequently in the three types of leukemia than in tuberculosis (both with
One-Time Universal Hashing Quantum Digital Signatures without Perfect Keys
Quantum digital signatures (QDS), generating correlated bit strings among
three remote parties for signatures through quantum law, can guarantee
non-repudiation, authenticity, and integrity of messages. Recently, one-time
universal hashing QDS framework, exploiting the quantum asymmetric encryption
and universal hash functions, has been proposed to significantly improve the
signature rate and ensure unconditional security by directly signing the hash
value of long messages. However, similar to quantum key distribution, this
framework utilizes keys with perfect secrecy by performing privacy
amplification that introduces cumbersome matrix operations, thereby consuming
large computational resources, causing delays and increasing failure
probability. Here, we prove that, different from private communication,
imperfect quantum keys with limited information leakage can be used for digital
signatures and authentication without compromising the security while having
eight orders of magnitude improvement on signature rate for signing a megabit
message compared with conventional single-bit schemes. This study significantly
reduces the delay for data postprocessing and is compatible with any quantum
key generation protocols. In our simulation, taking two-photon twin-field key
generation protocol as an example, QDS can be practically implemented over a
fiber distance of 650 km between the signer and receiver. For the first time,
this study offers a cryptographic application of quantum keys with imperfect
secrecy and paves a way for the practical and agile implementation of digital
signatures in a future quantum network.Comment: Comments are welcome
Breaking universal limitations on quantum conference key agreement without quantum memory
Quantum conference key agreement is an important cryptographic primitive for
future quantum network. Realizing this primitive requires high-brightness and
robust multiphoton entanglement sources, which is challenging in experiment and
unpractical in application because of limited transmission distance caused by
channel loss. Here we report a measurement-device-independent quantum
conference key agreement protocol with enhanced transmission efficiency over
lossy channel. With spatial multiplexing nature and adaptive operation, our
protocol can break key rate bounds on quantum communication over quantum
network without quantum memory. Compared with previous work, our protocol shows
superiority in key rate and transmission distance within the state-of-the-art
technology. Furthermore, we analyse the security of our protocol in the
composable framework and evaluate its performance in the finite-size regime to
show practicality. Based on our results, we anticipate that our protocol will
play an indispensable role in constructing multipartite quantum network
Breaking Rate-Distance Limitation of Measurement-Device-Independent Quantum Secret Sharing
Quantum secret sharing is an important cryptographic primitive for network
applications ranging from secure money transfer to multiparty quantum
computation. Currently most progresses on quantum secret sharing suffer from
rate-distance bound, and thus the key rates are limited and unpractical for
large-scale deployment. Furthermore, the performance of most existing protocols
is analyzed in the asymptotic regime without considering participant attacks.
Here we report a measurement-device-independent quantum secret sharing protocol
with improved key rate and transmission distance. Based on spatial
multiplexing, our protocol shows it can break rate-distance bounds over network
under at least ten communication parties. Compared with other protocols, our
work improves the secret key rate by more than two orders of magnitude and has
a longer transmission distance. We analyze the security of our protocol in the
composable framework considering participant attacks. Based on the security
analysis, we also evaluate their performance in the finite-size regime. In
addition, we investigate applying our protocol to digital signatures where the
signature rate is improved more than times compared with existing
protocols. Based on our results, we anticipate that our quantum secret sharing
protocol will provide a solid future for multiparty applications on quantum
network.Comment: arXiv admin note: text overlap with arXiv:2212.0522
All-Photonic Quantum Repeater for Multipartite Entanglement Generation
Quantum network applications like distributed quantum computing and quantum
secret sharing present a promising future network equipped with quantum
resources. Entanglement generation and distribution over long distances is
critical and unavoidable to utilize quantum technology in a fully-connected
network. The distribution of bipartite entanglement over long distances has
seen some progresses, while the distribution of multipartite entanglement over
long distances remains unsolved. Here we report a two-dimensional quantum
repeater protocol for the generation of multipartite entanglement over long
distances with all-photonic framework to fill this gap. The yield of the
proposed protocol shows long transmission distance under various numbers of
network users. With the improved efficiency and flexibility of extending the
number of users, we anticipate that our protocol can work as a significant
building block for quantum networks in the future
Testing and Data Reduction of the Chinese Small Telescope Array (CSTAR) for Dome A, Antarctica
The Chinese Small Telescope ARray (hereinafter CSTAR) is the first Chinese
astronomical instrument on the Antarctic ice cap. The low temperature and low
pressure testing of the data acquisition system was carried out in a laboratory
refrigerator and on the 4500m Pamirs high plateau, respectively. The results
from the final four nights of test observations demonstrated that CSTAR was
ready for operation at Dome A, Antarctica. In this paper we present a
description of CSTAR and the performance derived from the test observations.Comment: Accepted Research in Astronomy and Astrophysics (RAA) 1 Latex file
and 20 figure
Experimental quantum secure network with digital signatures and encryption
Cryptography promises four information security objectives, namely,
confidentiality, integrity, authenticity, and non-repudiation, to support
trillions of transactions annually in the digital economy. Efficient digital
signatures, ensuring the integrity, authenticity, and non-repudiation of data
with information-theoretical security are highly urgent and intractable open
problems in cryptography. Here, we propose a protocol of high-efficiency
quantum digital signatures using secret sharing, one-time universal
hashing, and the one-time pad. We just need to use a 384-bit key to sign
documents of up to lengths with a security bound of . If
one-megabit document is signed, the signature efficiency is improved by more
than times compared with previous quantum digital signature protocols.
Furthermore, we build the first all-in-one quantum secure network integrating
information-theoretically secure communication, digital signatures, secret
sharing, and conference key agreement and experimentally demonstrate this
signature efficiency advantage. Our work completes the cryptography toolbox of
the four information security objectives.Comment: 19 pages, 7 figures, 4 tables. Quantum digital signatures and quantum
private communication maintain a consistent level of practicalit
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