4,768 research outputs found
Exponential Separation of Quantum and Classical Non-Interactive Multi-Party Communication Complexity
We give the first exponential separation between quantum and classical
multi-party communication complexity in the (non-interactive) one-way and
simultaneous message passing settings.
For every k, we demonstrate a relational communication problem between k
parties that can be solved exactly by a quantum simultaneous message passing
protocol of cost O(log n) and requires protocols of cost n^{c/k^2}, where c>0
is a constant, in the classical non-interactive one-way message passing model
with shared randomness and bounded error.
Thus our separation of corresponding communication classes is superpolynomial
as long as k=o(\sqrt{\log n / \log\log n}) and exponential for k=O(1)
Quantum Cryptography Beyond Quantum Key Distribution
Quantum cryptography is the art and science of exploiting quantum mechanical
effects in order to perform cryptographic tasks. While the most well-known
example of this discipline is quantum key distribution (QKD), there exist many
other applications such as quantum money, randomness generation, secure two-
and multi-party computation and delegated quantum computation. Quantum
cryptography also studies the limitations and challenges resulting from quantum
adversaries---including the impossibility of quantum bit commitment, the
difficulty of quantum rewinding and the definition of quantum security models
for classical primitives. In this review article, aimed primarily at
cryptographers unfamiliar with the quantum world, we survey the area of
theoretical quantum cryptography, with an emphasis on the constructions and
limitations beyond the realm of QKD.Comment: 45 pages, over 245 reference
- …