45 research outputs found
Kak's three-stage protocol of secure quantum communication revisited: Hitherto unknown strengths and weaknesses of the protocol
Kak's three-stage protocol for quantum key distribution is revisited with
special focus on its hitherto unknown strengths and weaknesses. It is shown
that this protocol can be used for secure direct quantum communication.
Further, the implementability of this protocol in the realistic situation is
analyzed by considering various Markovian noise models. It is found that the
Kak's protocol and its variants in their original form can be implemented only
in a restricted class of noisy channels, where the protocols can be transformed
to corresponding protocols based on logical qubits in decoherence free
subspace. Specifically, it is observed that Kak's protocol can be implemented
in the presence of collective rotation and collective dephasing noise, but
cannot be implemented in its original form in the presence of other types of
noise, like amplitude damping and phase damping noise. Further, the performance
of the protocol in the noisy environment is quantified by computing average
fidelity under various noise models, and subsequently a set of preferred states
for secure communication in noisy environment have also been identified.Comment: Kak's protocol is not suitable for quantum cryptography in presence
of nois
Kak's three-stage protocol of secure quantum communication revisited: Hitherto unknown strengths and weaknesses of the protocol
Kak's three-stage protocol for quantum key distribution is revisited with
special focus on its hitherto unknown strengths and weaknesses. It is shown
that this protocol can be used for secure direct quantum communication.
Further, the implementability of this protocol in the realistic situation is
analyzed by considering various Markovian noise models. It is found that the
Kak's protocol and its variants in their original form can be implemented only
in a restricted class of noisy channels, where the protocols can be transformed
to corresponding protocols based on logical qubits in decoherence free
subspace. Specifically, it is observed that Kak's protocol can be implemented
in the presence of collective rotation and collective dephasing noise, but
cannot be implemented in its original form in the presence of other types of
noise, like amplitude damping and phase damping noise. Further, the performance
of the protocol in the noisy environment is quantified by computing average
fidelity under various noise models, and subsequently a set of preferred states
for secure communication in noisy environment have also been identified.Comment: Kak's protocol is not suitable for quantum cryptography in presence
of nois
Analysing QBER and secure key rate under various losses for satellite based free space QKD
Quantum Key Distribution is a key distribution method that uses the qubits to
safely distribute one-time use encryption keys between two or more authorised
participants in a way that ensures the identification of any eavesdropper. In
this paper, we have done a comparison between the BB84 and B92 protocols and
BBM92 and E91 entanglement based protocols for satellite based uplink and
downlink in low Earth orbit. The expressions for the quantum bit error rate and
the keyrate are given for all four protocols. The results indicate that, when
compared to the B92 protocol, the BB84 protocol guarantees the distribution of
a higher secure keyrate for a specific distance. Similarly, it is observed that
BBM92 ensures higher keyrate in comparison with E91 protocol
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
Quantum dots for photonic quantum information technology
The generation, manipulation, storage, and detection of single photons play a
central role in emerging photonic quantum information technology. Individual
photons serve as flying qubits and transmit the quantum information at high
speed and with low losses, for example between individual nodes of quantum
networks. Due to the laws of quantum mechanics, quantum communication is
fundamentally tap-proof, which explains the enormous interest in this modern
information technology. On the other hand, stationary qubits or photonic states
in quantum computers can potentially lead to enormous increases in performance
through parallel data processing, to outperform classical computers in specific
tasks when quantum advantage is achieved. Here, we discuss in depth the great
potential of quantum dots (QDs) in photonic quantum information technology. In
this context, QDs form a key resource for the implementation of quantum
communication networks and photonic quantum computers because they can generate
single photons on-demand. Moreover, QDs are compatible with the mature
semiconductor technology, so that they can be integrated comparatively easily
into nanophotonic structures, which form the basis for quantum light sources
and integrated photonic quantum circuits. After a thematic introduction, we
present modern numerical methods and theoretical approaches to device design
and the physical description of quantum dot devices. We then present modern
methods and technical solutions for the epitaxial growth and for the
deterministic nanoprocessing of quantum devices based on QDs. Furthermore, we
present the most promising concepts for quantum light sources and photonic
quantum circuits that include single QDs as active elements and discuss
applications of these novel devices in photonic quantum information technology.
We close with an overview of open issues and an outlook on future developments.Comment: Copyright 2023 Optica Publishing Group. One print or electronic copy
may be made for personal use only. Systematic reproduction and distribution,
duplication of any material in this paper for a fee or for commercial
purposes, or modifications of the content of this paper are prohibite