20 research outputs found
Counterfactual quantum certificate authorization
We present a multi-partite protocol in a counterfactual paradigm. In
counterfactual quantum cryptography, secure information is transmitted between
two spatially separated parties even when there is no physical travel of
particles transferring the information between them. We propose here a
tripartite counterfactual quantum protocol for the task of certificate
authorization. Here a trusted third party, Alice, authenticates an entity Bob
(e.g., a bank) that a client Charlie wishes to securely transact with. The
protocol is counterfactual with respect to either Bob or Charlie. We prove its
security against a general incoherent attack, where Eve attacks single
particles.Comment: 6 pages, 2 figures, close to the published versio
Quantum cryptography: key distribution and beyond
Uniquely among the sciences, quantum cryptography has driven both
foundational research as well as practical real-life applications. We review
the progress of quantum cryptography in the last decade, covering quantum key
distribution and other applications.Comment: It's a review on quantum cryptography and it is not restricted to QK
Unbounded sequence of observers exhibiting Einstein-Podolsky-Rosen steering
A sequential steering scenario is investigated, where multiple Bobs aim at
demonstrating steering using successively the same half of an entangled quantum
state. With isotropic entangled states of local dimension , the number of
Bobs that can steer Alice is found to be , thus
leading to an arbitrary large number of successive instances of steering with
independently chosen and unbiased inputs. This scaling is achieved when
considering a general class of measurements along orthonormal bases, as well as
complete sets of mutually unbiased bases. Finally, we show that similar results
can be obtained in an anonymous sequential scenario, where none of the Bobs
know their position in the sequence.Comment: 7 pages, 4 figure