We present a quantum key distribution scheme using a weak-coupling cavity QED regime based on quantum dense coding. Hybrid entanglement states of photons and electrons are used to distribute information. We just need to transmit photons without storing them in the scheme. The electron confined in a quantum dot, which is embedded in a microcavity, is held by one of the legitimate users throughout the whole communication process. Only the polarization of a single photon and spin of electron measurements are applied in this protocol, which are easier to perform than collective-Bell state measurements. Linear optical apparatus, such as a special polarizing beam splitter in a circular basis and single photon operations, make it more flexible to realize under current technology. Its efficiency will approach 100% in the ideal case. The security of the scheme is also discussed.
We present a quantum key distribution scheme using a weak-coupling cavity QED regime based on quantum dense coding. Hybrid entanglement states of photons and electrons are used to distribute information. We just need to transmit photons without storing them in the scheme. The electron confined in a quantum dot, which is embedded in a microcavity, is held by one of the legitimate users throughout the whole communication process. Only the polarization of a single photon and spin of electron measurements are applied in this protocol, which are easier to perform than collective-Bell state measurements. Linear optical apparatus, such as a special polarizing beam splitter in a circular basis and single photon operations, make it more flexible to realize under current technology. Its efficiency will approach 100% in the ideal case. The security of the scheme is also discussed.
We propose a theoretical scheme for secure quantum key distribution network following the ideas in quantum dense coding. In this scheme, the server of the network provides the service for preparing and measuring the Bell states, and the users encode the states with local unitary operations. For preventing the server from eavesdropping, we design a decoy when the particle is transmitted between the users. The scheme has high capacity as one particle carries two bits of information and its efficiency for qubits approaches 100%. Moreover, it is unnecessary for the users to store the quantum states, which makes this scheme more convenient in applications than others.
Two-qubit quantum codes have been suggested to obtain better efficiency and higher loss tolerance in quantum key distribution. Here, we propose a two-qubit quantum key distribution protocol based on a mixed basis consisting of two Bell states and two states from the computational basis. All states can be generated from a single entangled photon pair resource by using local operations on only one auxiliary photon. Compared to other schemes it is also possible to deterministically discriminate all states using linear optics. Additionally, our protocol can be implemented with today's technology. When discussing the security of our protocol we find a much improved resistance against certain attacks as compared to the standard BB84 protocol.
We propose a theoretical scheme for secure quantum key distribution network following the ideas m quantum aense coding. In this scheme, the server of the network provides the service for preparing and measuring the Bell states,and the users encode the states with local unitary operations. For preventing the server from eavesdropping, we design a decoy when the particle is transmitted between the users. The scheme has high capacity as one particle carries two bits of information and its efficiency for qubits approaches 100%. Moreover, it is unnecessary for the users to store the quantum states, which makes this scheme more convenient in applications than others.
We propose a quantum key distribution (QKD) scheme in which four parties can simultaneously share a secret key via optical device. The participants divide the communication into two modes, namely, detecting mode and message mode. Taking advantage of controlled secret short key technology, the participants together can achieve the detecting mode or the message mode by switching between their two sets of optical devices. In the detecting mode, the key distributer Alice utilizes a single-photon state resource and two beam splitters and the other three participants Bob, Charlie and Dick use first-type devices to detect the superposition of vacuum and single-particle states. Hence, any eavesdropping can be found by using a variant of Bell's inequality. In the message mode, Alice uses a two-photon Bell-state resource and two polarization beam splitters instead of the single-particle state resource and beam splitters used in the detecting mode and the other three participants use second-type devices to detect photons. In this case, the secret key can be successfully distributed from Alice to the other three ones. Moreover, the present four-party QKD scheme can be generalized to a 2n-party QKD scheme by using n-photon Greenberg–Horne–Zeilinger.
Quantum key distribution technology refers to a method to share keys between communication parties by transmitting quantum states in public channels. Although unconditional security is the main advantage of QKD, its application prospect has been controversial in practical implementation due to the potential security risks caused by device imperfections. Fortunately, the measurement device independent quantum key distribution protocol removes the vulnerability of all measurement devices and greatly improves the practical security of the quantum key distribution system. However, the security key rate of this protocol is still lower than that of other quantum key distribution protocols. At present, using high-dimensional coding to improve the performance of the quantum key distribution protocol has been proved in theory and experiment, and recently, it has been proposed to use high-dimensional coding to improve the performance of measurement device independent quantum key distribution protocol, but because these protocols have higher requirements for the laboratory equipment performance, that the high-dimensional encoding is applied to the aforementioned protocol still has many difficulties in practical application. In this paper, we propose a hybrid coding based on the polarization and two-degree phase of freedom measurement device independent quantum key distribution protocol. In the first place in an ideal case, we introduce in detail the protocol decoding rules, then introduce 4intensity decoy-state method to solve the problem of actual light source multiphoton, in addition we also consider the statistical fluctuation effect under the condition of limited code length, channel loss, actual dark count of single photon detector and detection efficiency problem. Finally, the optimal security code rate and its corresponding optimal parameters are obtained by full parameter optimization method, And the numerical simulation results show that the security key rate of this protocol is increased by 50% by considering the practical implementation. We point out that compared with other measurement device independent quantum key distribution protocol, the proposed agreement requires local users only to have a phase encoding device and a polarization coding device, and 4 single photon detectors for detecting side. The proposed device can use the existing experimental condition, beyond that, compared with the time encoding based high dimensional measurement device independent quantum key distribution protocol, the proposed protocol possesses the advantage that the rate of system security key can be increased without increasing the repetition frequency of users. It is proved that this protocol has great application value in the future field of quantum communication, especially, in the field of quantum network communication.
A quantum key distribution protocol, based on the quantum dense encoding in entangled states, is presented. In this protocol, we introduce an encoding process to encode,two classical bits information into one of the four one-qubit unitary operations implemented by Alice and the Bell states measurement implemented by Bob in stead of direct measuring the previously shared Einstein-Podolsky-Rosen pairs by both of the distant parties, Alice and Bob Considering the practical application we can get the conclusion that our protocol has some advantages. It not only simplifies the measurement which may induce potential errors, but also improves the effectively transmitted rate of the generated qubits by the raw key. Here we also discuss eavesdropping attacks against the scheme and the channel loss.