732 research outputs found
Semi-quantum communication: Protocols for key agreement, controlled secure direct communication and dialogue
Semi-quantum protocols that allow some of the users to remain classical are
proposed for a large class of problems associated with secure communication and
secure multiparty computation. Specifically, first time semi-quantum protocols
are proposed for key agreement, controlled deterministic secure communication
and dialogue, and it is shown that the semi-quantum protocols for controlled
deterministic secure communication and dialogue can be reduced to semi-quantum
protocols for e-commerce and private comparison (socialist millionaire
problem), respectively. Complementing with the earlier proposed semi-quantum
schemes for key distribution, secret sharing and deterministic secure
communication, set of schemes proposed here and subsequent discussions have
established that almost every secure communication and computation tasks that
can be performed using fully quantum protocols can also be performed in
semi-quantum manner. Further, it addresses a fundamental question in context of
a large number problems- how much quantumness is (how many quantum parties are)
required to perform a specific secure communication task? Some of the proposed
schemes are completely orthogonal-state-based, and thus, fundamentally
different from the existing semi-quantum schemes that are
conjugate-coding-based. Security, efficiency and applicability of the proposed
schemes have been discussed with appropriate importance.Comment: 19 pages 1 figur
Quantum e-commerce: A comparative study of possible protocols for online shopping and other tasks related to e-commerce
A set of quantum protocols for online shopping is proposed and analyzed to
establish that it is possible to perform secure online shopping using different
types of quantum resources. Specifically, a single photon based, a Bell state
based and two 3-qubit entangled state based quantum online shopping schemes are
proposed. The Bell state based scheme, being a completely orthogonal state
based protocol, is fundamentally different from the earlier proposed schemes
which were based on conjugate coding. One of the 3-qubit entangled state based
scheme is build on the principle of entanglement swapping which enables us to
accomplish the task without transmission of the message encoded qubits through
the channel. Possible ways of generalizing the entangled state based schemes
proposed here to the schemes which use multiqubit entangled states is also
discussed. Further, all the proposed protocols are shown to be free from the
limitations of the recently proposed protocol of Huang et al. (Quantum Inf.
Process. 14, 2211-2225, 2015) which allows the buyer (Alice) to change her
order at a later time (after initially placing the order and getting it
authenticated by the controller). The proposed schemes are also compared with
the existing schemes using qubit efficiency.Comment: It's shown that quantum e-commerce is not a difficult task, and it
can be done in various way
Energy efficient mining on a quantum-enabled blockchain using light
We outline a quantum-enabled blockchain architecture based on a consortium of
quantum servers. The network is hybridised, utilising digital systems for
sharing and processing classical information combined with a fibre--optic
infrastructure and quantum devices for transmitting and processing quantum
information. We deliver an energy efficient interactive mining protocol enacted
between clients and servers which uses quantum information encoded in light and
removes the need for trust in network infrastructure. Instead, clients on the
network need only trust the transparent network code, and that their devices
adhere to the rules of quantum physics. To demonstrate the energy efficiency of
the mining protocol, we elaborate upon the results of two previous experiments
(one performed over 1km of optical fibre) as applied to this work. Finally, we
address some key vulnerabilities, explore open questions, and observe
forward--compatibility with the quantum internet and quantum computing
technologies.Comment: 25 pages, 5 figure
Quantum Conference
A notion of quantum conference is introduced in analogy with the usual notion
of a conference that happens frequently in today's world. Quantum conference is
defined as a multiparty secure communication task that allows each party to
communicate their messages simultaneously to all other parties in a secure
manner using quantum resources. Two efficient and secure protocols for quantum
conference have been proposed. The security and efficiency of the proposed
protocols have been analyzed critically. It is shown that the proposed
protocols can be realized using a large number of entangled states and group of
operators. Further, it is shown that the proposed schemes can be easily reduced
to protocol for multiparty quantum key distribution and some earlier proposed
schemes of quantum conference, where the notion of quantum conference was
different.Comment: 12 pages, 1 figur
A Simplified Hierarchical Dynamic Quantum Secret Sharing Protocol with Added Features
Generalizing the notion of dynamic quantum secret sharing (DQSS), a
simplified protocol for hierarchical dynamic quantum secret sharing (HDQSS) is
proposed and it is shown that the protocol can be implemented using any
existing protocol of quantum key distribution, quantum key agreement or secure
direct quantum communication. The security of this proposed protocol against
eavesdropping and collusion attacks is discussed with specific attention
towards the issues related to the composability of the subprotocols that
constitute the proposed protocol. The security and qubit efficiency of the
proposed protocol is also compared with that of other existing protocols of
DQSS. Further, it is shown that it is possible to design a semi-quantum
protocol of HDQSS and in principle, the protocols of HDQSS can be implemented
using any quantum state. It is also noted that the completely
orthogonal-state-based realization of HDQSS protocol is possible and that HDQSS
can be experimentally realized using a large number of alternative approaches.Comment: 9 pages, 1 figur
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