32 research outputs found
A comparative study of protocols for secure quantum communication under noisy environment: single-qubit-based protocols versus entangled-state-based protocols
The effect of noise on various protocols of secure quantum communication has
been studied. Specifically, we have investigated the effect of amplitude
damping, phase damping, squeezed generalized amplitude damping, Pauli type as
well as various collective noise models on the protocols of quantum key
distribution, quantum key agreement,quantum secure direct quantum communication
and quantum dialogue. From each type of protocol of secure quantum
communication, we have chosen two protocols for our comparative study; one
based on single qubit states and the other one on entangled states. The
comparative study reported here has revealed that single-qubit-based schemes
are generally found to perform better in the presence of amplitude damping,
phase damping, squeezed generalized amplitude damping noises, while
entanglement-based protocols turn out to be preferable in the presence of
collective noises. It is also observed that the effect of noise entirely
depends upon the number of rounds of quantum communication involved in a scheme
of quantum communication. Further, it is observed that squeezing, a completely
quantum mechanical resource present in the squeezed generalized amplitude
channel, can be used in a beneficial way as it may yield higher fidelity
compared to the corresponding zero squeezing case.Comment: 23 pages 7 figure
Orthogonal-state-based protocols of quantum key agreement
Two orthogonal-state-based protocols of quantum key agreement (QKA) are
proposed. The first protocol of QKA proposed here is designed for two-party
QKA, whereas the second protocol is designed for multi-party QKA. Security of
these orthogonal-state-based protocols arise from monogamy of entanglement.
This is in contrast to the existing protocols of QKA where security arises from
the use of non-orthogonal state (non-commutativity principle). Further, it is
shown that all the quantum systems that are useful for implementation of
quantum dialogue and most of the protocols of secure direct quantum
communication can be modified to implement protocols of QKA.Comment: 9 pages, no figur
Experimental Test of Two-way Quantum Key Distribution in Presence of Controlled Noise
We describe the experimental test of a quantum key distribution performed
with a two-way protocol without using entanglement. An individual incoherent
eavesdropping is simulated and induces a variable amount of noise on the
communication channel. This allows a direct verification of the agreement
between theory and practice.Comment: 4 pages, 3 figure
Two-step orthogonal-state-based protocol of quantum secure direct communication with the help of order-rearrangement technique
The Goldenberg-Vaidman (GV) protocol for quantum key distribution (QKD) uses
orthogonal encoding states of a particle. Its security arises because
operations accessible to Eve are insufficient to distinguish the two states
encoding the secret bit. We propose a two-particle cryptographic protocol for
quantum secure direct communication, wherein orthogonal states encode the
secret, and security arises from restricting Eve from accessing any
two-particle operations. However, there is a non-trivial difference between the
two cases. While the encoding states are perfectly indistinguishable in GV,
they are partially distinguishable in the bi-partite case, leading to a
qualitatively different kind of information-vs-disturbance trade-off and also
options for Eve in the two cases.Comment: 9 pages, 4 figures, LaTex, Accepted for publication in Quantum
Information Processing (2014
Experimental Study of the Quantum States of Light and Realization of a Quantum Communication Protocol\ud
I present how to obtain and characterize quantum states of light potentially useful for quantum communication protocols. The control of the frequency correlations,\ud
and the bandwidth, of single and paired photons is an essential ingredient in specific quantum applications, from quantum imaging to quantum clock synchronization.\ud
I show both theoretical and experimental spectral correlations of pairs of photons generated in non-collinear spontaneous parametric down conversion (SPDC). In the second part of the work, a scheme for quantum key distribution using the two-way LM05 protocol [PRL 94, 140501 (2005)] and its implementation is presented too. A preliminary transmission test is discussed together with\ud
an experimental study for the security of the generated key in presence of noise in the channels. The noise is modulated as to simulate the effect of an eavesdropper.\u