Quantum Teleportation and Dense Coding in Multiple Bosonic Reservoirs

The effect of a reservoir on quantum communication depends on its spectral density. The efficiency of quantum teleportation and dense coding is explored when each one of the channel qubits is coupled simultaneously to multiple bosonic reservoirs. It is shown that the non-Markovianity triggered by increasing the reservoir number can induce revivals of quantum advantages of the two protocols after their disappearance. However, the backflow of information to the system that signifies non-Markovianity does not always induce immediate revivals of the quantum advantages. There may be a delayed effect for some initial states, and only as the backflow of information accumulates to a certain extent can the revivals of quantum advantages be triggered.     

Quantum Non-Markovian Environment-to-System Backflows of Information: Nonoperational vs. Operational Approaches

Quantum memory effects can be qualitatively understood as a consequence of an environment-to-system backflow of information. Here, we analyze and compare how this concept is interpreted and implemented in different approaches to quantum non-Markovianity. We study a nonoperational approach, defined by the distinguishability between two system states characterized by different initial conditions, and an operational approach, which is defined by the correlation between different outcomes associated to successive measurement processes performed over the system of interest. The differences, limitations, and vantages of each approach are characterized in detail by considering diverse system–environment models and dynamics. As a specific example, we study a non-Markovian depolarizing map induced by the interaction of the system of interest with an environment characterized by incoherent and coherent self-dynamics.     

Prospecting Quantum Correlations and Examining Teleportation Fidelity in a Pair of Coupled Double Quantum Dots System

The topic of improving the ability of quantum systems to retain non-local features and enhance the efficiency of quantum protocols continues. This study delves into the thermal investigation of quantum correlations and teleportation fidelity of a two-qubit teleported state using excess electrons in a coupled double quantum dots system as a quantum channel. The study employs three reliable quantum quantifiers to prospect the resourcefulness and non-classicality of the system. The findings suggest that preserving quantum correlations and optimizing teleportation fidelity require minimizing tunneling coupling and maximizing Coulomb interaction. The study has significant implications for quantum physics and its practical applications in quantum information processing.     

Multiparty Quantum Secret Sharing of Secure Direct Communication Using Teleportation

We present an (n,n) threshold quantum secret sharing scheme of secure direct communication using Greenberger-Horne-Zeilinger state and teleportation.After ensuring the security of the quantum channel,the sender encodes the secret message directly on a sequence of particle states and transmits it to the receivers by teleportation.The receivers can recover the secret message by combining their measurement results with the sender's result.If a perfect quantum channel is used,our scheme is completely secure because the transmitting particle sequence does not carry the secret message.We also show our scheme is secure for noise quantum channel.     

Quantum Teleportation of One-to-Many Using （n ＋ 1）-Particle Entanglement

In this paper, quantum teleportatlon of one-to-many using （n ＋1）-particle entanglement is presented. If the sender （Alice） wants to transmit an unknown quantum state to a distant receiver （Bob）, similar to the previous schemes, Alice performs Bell-state measurement on particles belonging to herself and informs the receiver the results through the classical channel. After that, it needs to perform the Hadamard operation on the other （n - 1） particles and measure them as well. With the aid of the measurement results, Bob can operate a corresponding unitary transformation on his particle to reconstruct the original state. Of course, the reconstruction may realize at either location of n, but it cannot realize at all locations at the same time.     

Best Fidelity Conditions for Three Party Quantum Teleportation

Using the entangled three qubit states classified by Acin et al. we find the best fidelity conditions for quantum teleportation among three parties.     

Perfect Biparticle Teleportation by Using Multi-particle Quantum Channel with Joint Measurement

In this paper, we reinvestigate the faithful quantum teleportation of an arbitrary two-qubit state by a multi-particle channel with multi-particle joint measurements. The relationship between multi-particle quantum channel and the multi-particle joint measurement bases has been found. In addition, we show how to construct the multi-particle joint measurement bases.     

Many-Agent Controlled Teleportation of Multi-qubit Quantum Information via Quantum Entanglement Swapping

We present a method to teleport multi-qubit quantum information in an easy way from a sender to a receiver via the control of many agents in a network. Only when all the agents collaborate with the quantum information receiver can the unknown states in the sender＇s qubits be fully reconstructed in the receiver＇s qubits. In our method, agents＇s control parameters are obtained via quantum entanglement swapping. As the realization of the many-agent controlled teleportation is concerned, compared to the recent method [G.P. Yang, et al., Phys. Rev. A 70 （2004） 022329], our present method considerably reduces the preparation difficulty of initial states and the identification difficulty of entangled states, moreover, it does not need local Hadamard operations and it is more feasible in technology.     

Many-Agent Controlled Teleportation of Multi-qubit Quantum Information via Quantum Entanglement Swapping

We present a method to teleport multi-qubit quantum information in an easy way from a sender to a receiver via the control of many agents in a network. Only when all the agents collaborate with the quantum information receiver can the unknown states in the sender‘s qubits be fully reconstructed in the receiver‘s qubits. In our method,agents‘s control parameters are obtained via quantum entanglement swapping. As the realization of the many-agent controlled teleportation is concerned, compared to the recent method [C.P. Yang, et al., Phys. Rev. A 70 (2004) 022329],our present method considerably reduces the preparation difficulty of initial states and the identification difficulty of entangled states, moreover, it does not need local Hadamard operations and it is more feasible in technology.     

Teleportation of Any Form of Two-Mode Quantum States

By using two two-mode Einstein–Podolsky–Rosen (EPR) pair eigenstates or two two-mode squeezed states as quantum channels we study the quantum teleportation of any form of two-mode quantum states, which conclude discrete and continuous variable quantum states.     

Quantum Secure Direct Communication Using Six-Particle Maximally Entangled States and Teleportation

The sender shares six-particle maximally entangled states as quantum channel with the receiver. If the quantum channel is secure, the sender performs projective measurements and tells the measurement outcome to the receiver. The receiver performs the unitary transformations and makes projective measurements on his particles to obtain the secret information. Using teleportation, the transmission of three-qubit secret information can be completed in each quantum channel     

Unidirectional Quantum Remote Control:Teleportation of Control-State

We investigate the problem of teleportation of unitary operations by unidirectional control-state telepor-tation and propose a scheme called unidirectional quantum remote control. The scheme is based on the isomorphismbetween operation and state. It allows us to store a unitary operation in a control state, thereby teleportation of theunitary operation can be implemented by unidirectional teleportation of the control-state. We find that the probabilityof success for implementing an arbitrary unitary operation on arbitrary M-qubit state by unidirectional control-stateteleportation is 4-M, and 2M ebits and 4M cbits are consumed in each teleportation.     

Memory Effects in Quantum Dynamics Modelled by Quantum Renewal Processes

Simple, controllable models play an important role in learning how to manipulate and control quantum resources. We focus here on quantum non-Markovianity and model the evolution of open quantum systems by quantum renewal processes. This class of quantum dynamics provides us with a phenomenological approach to characterise dynamics with a variety of non-Markovian behaviours, here described in terms of the trace distance between two reduced states. By adopting a trajectory picture for the open quantum system evolution, we analyse how non-Markovianity is influenced by the constituents defining the quantum renewal process, namely the time-continuous part of the dynamics, the type of jumps and the waiting time distributions. We focus not only on the mere value of the non-Markovianity measure, but also on how different features of the trace distance evolution are altered, including times and number of revivals.     

Two Quantum Proxy Blind Signature Schemes Based on Controlled Quantum Teleportation

We present a scheme for teleporting an unknown, two-particle entangled state with a message from a sender (Alice) to a receiver (Bob) via a six-particle entangled channel. We also present another scheme for teleporting an unknown one-particle entangled state with a message transmitted in a two-way form between the same sender and receiver via a five-qubit cluster state. One-way hash functions, Bell-state measurements, and unitary operations are adopted in these two schemes. Our schemes use the physical characteristics of quantum mechanics to implement delegation, signature, and verification processes. Moreover, a quantum key distribution protocol and a one-time pad are adopted in these schemes.     

Probabilistic Teleportation of Multi-particle d-Level Quantum State

The general scheme for teleportation of a multi-particle d-level quantum state is presented when m pairs of partially entangled particles are utilized as quantum channels. The probabilistic teleportation can be achieved with a successful probability of $ \prod \limits_{N=0}^{d-1} ({C_0^N})^2/{d^M}$, which is determined by the smallest coefficients of each entangled channels.     

Unidirectional Quantum Remote Control： Teleportation of Control－State

We investigate the problem of teleportation of unitary operations by unidirectional control-state telepor-ration and propose a scheme called unidirectional quantum remote control. The scheme is based on the isomorphism between operation and state. It allows us to store a unitary operation in a control state, thereby teleportatSon of the unitary operation can be implemented by unidirectional teleportation of the control-state. We find that the probability of success for implementing an arbitrary unitary operation on arbitrary A~-qubit state by unidirectional control-state teleportation is 4^-M, and 2M ebits and 4M cbits are consumed in each teleportation.     

Quantum Logic Networks for Probabilistic and Controlled Teleportation of Unknown Quantum States

We present simplification schemes for probabilistic and controlled teleportation of the unknown quantum states of both one particle and two particles and construct efficient quantum logic networks for implementing the new schemes by means of the primitive operations consisting of single-qubit gates, two-qubit controlled-not gates, Von Neumann measurement, and classically controlled operations. In these schemes the teleportation are not always successful but with certain probability.     

Quantum Logic Networks for Probabilistic and Controlled Teleportation of Unknown Quantum States

We present simplification schemes for probabilistic and controlled teleportation of the unknown quantum states of both one particle and two particles and construct efficient quantum logic networks for implementing the new schemes by means of the primitive operations consisting of single-qubit gates, two-qubit controlled-not gates, Von Neumann measurement, and classically controlled operations. In these schemes the teleportation are not always successful but with certain probability.     

Controlled Teleportation of Multi-qutrit Quantum Information by Swapping Entanglement

We present a scheme for teleporting multi-qutrit quantum information from a sender to a receiver via the control of many agents in a network. Agents＇s control parameters are obtained via quantum entanglement swapping. In our scheme, Zhang and Man＇s QSS protocol [Phys. Rev. A 72 （2005） 022303] based on Bell-state entanglement swapping is generalized to a qutrit case. Our scheme owns the advantage of having higher code capacity and better security than the work [Commun. Theor. Phys. 44 （2005） 847] on controlled teleportation for multi-qubit.