Protected simultaneous quantum remote state preparation scheme by weak and reversal measurements in noisy environments

We discuss a quantum remote state preparation protocol by which two parties, Alice and Candy, prepare a single-qubit and a two-qubit state, respectively, at the site of the receiver Bob. The single-qubit state is known to Alice while the two-qubit state which is a non-maximally entangled Bell state is known to Candy. The three parties are connected through a single entangled state which acts as a quantum channel. We first describe the protocol in the ideal case when the entangled channel under use is in a pure state. After that, we consider the effect of amplitude damping(AD) noise on the quantum channel and describe the protocol executed through the noisy channel. The decrement of the fidelity is shown to occur with the increment in the noise parameter. This is shown by numerical computation in specific examples of the states to be created. Finally, we show that it is possible to maintain the label of fidelity to some extent and hence to decrease the effect of noise by the application of weak and reversal measurements. We also present a scheme for the generation of the five-qubit entangled resource which we require as a quantum channel. The generation scheme is run on the IBMQ platform.

Controlled Cyclic Remote State Preparation of Arbitrary Qubit States

Quantum secure communications could securely transmit quantum information by using quantum resource.Recently,novel applications such as bidirectional and asymmetric quantum protocols have been developed.In this paper,we propose a new method for generating entanglement which is highly useful for multiparty quantum communications such as teleportation and Remote State Preparation(RSP).As one of its applications,we propose a new type of quantum secure communications,i.e.cyclic RSP protocols.Starting from a four-party controlled cyclic RSP protocol of one-qubit states,we show that this cyclic protocol can be generalized to a multiparty controlled cyclic RSP protocol for preparation of arbitrary qubit states.We point out that previous bidirectional and asymmetric protocols can be regarded as a simpler form of our cyclic RSP protocols.

Remote State Preparation of a Greenberger-Horne-Zeilinger Class State

In this paper, we propose a scheme for the remote preparation of a three-particle Greenberger-HorneZeilinger class state by a two-particle entangled state and a three-particle entangled state. It is shown that, by this scheme, only two classical bits and one two-particle projective measurement are enough for such preparation.

Deterministic joint remote state preparation of arbitrary single- and two-qubit states

In this paper, two novel schemes for deterministic joint remote state preparation（JRSP） of arbitrary single- and twoqubit states are proposed. A set of ingenious four-particle partially entangled states are constructed to serve as the quantum channels. In our schemes, two senders and one receiver are involved. Participants collaborate with each other and perform projective measurements on their own particles under an elaborate measurement basis. Based on their measurement results,the receiver can reestablish the target state by means of appropriate local unitary operations deterministically. Unit success probability can be achieved independent of the channel＇s entanglement degree.

Controlled Remote State Preparation

We present a scheme for remotely preparing a state via the controls of many agents in a network.In thescheme,the agents' controls are achieved by utilizing quantum key distribution.Generally,the original state can berestored by the receiver with probability 1/2 if all the agents collaborate.However,for certain type of original states therestoration probability is unit.

Trace Distance of Remote State Preparation Through Noisy Channels

In this paper, we study remote state preparation (RSP) by w state through noisy channels. The trace distance is used to describe how close the original state is to the output state. Studies show the trace distance is a function of decohenrence rates and angles of the state to be prepared. At the same time, we investigate the influence of different types of noises on the trace distance and find the various types of noises have different degrees of influence on the trace distance for a definite qubit. We also study changes of the trace distance against polar and azimuthal angles.

High effcient scheme for remote state preparation with cavity QED

In this paper, a scheme is proposed for remote state preparation （RSP） with cavity quantum electrodynamics （QED）. In our scheme, two observers share two-atom nonmaximally entangled state as quantum channels and can realize remote preparation of state of an atom. We also propose a generalization for remote preparation of N-atom entangled state by （N＋1）-atom GHZ-like state （N ≥ 2）. By this scheme, one single-atom projective measurement is enough for the RSP of a qubit or N-atom entangled state, and the probability of success for RSP is unity. Furthermore, we have considered the case where observers use W-like state as quantum channels to realize RSP of a qubit. We compare our scheme with existing ones.

Scheme for implementing perfect remote state preparation with W-class state in cavity QED

In this paper we present a remote state preparation scheme with a three-qubit W-class state in cavity QED. It has been shown that a special single-qubit state and a special two-qubit entangled state can be remotely prepared perfectly. Furthermore, the classical information cost in this scheme is less than that in the corresponding teleportation scheme and only a single-qubit projective measurement is made by the sender. We also generalize this idea to the multiqubit W-class state.

Deterministic joint remote state preparation of arbitrary two-and three-qubit states

We propose a novel deterministic protocol that two senders are capable of remotely preparing arbitrary two-and three-qubit states for a remote receiver using EPR pairs and GHZ state as the quantum channel.Compared with the existing deterministic protocols [An et al.2011 Phys.Lett.A 375 3570 and Chen et al.2012 J.Phys.A：Math.Theor.45 055303],the quantum resources and classical information in our scheme are decreased,and the whole operation process is simplified.

State Preparation in a Cold Atom Clock by Optical Pumping

We implement optical pumping to prepare cold atoms in our prototype of the ST Rb space cold atom clock, which operates in the one-way mode. Several modifications are made on our previous physical and optical system. The effective atomic signal in the top detection zone is increased to 2.5 times with 87% pumping efficiency. The temperature of the cold atom cloud is increased by 1.4 μK. We study the dependences of the effective signal gain and pumping efficiency on the pumping laser intensity and detuning. The effects of σ transition are discussed. This technique may be used in the future space cold atom clocks.

Influence of Noises on Remote State Preparation Using GHZ State

Using a quantum channel consisting of a GHZ state exposed to noisy environment,we investigate how toremotely prepare an entangled state and a qubit state,respectively.By solving the master equation in the Lindbladform,the influence of the various types of noises on the GHZ state is first discussed.Then we use the fidelity to describehow close the remotely prepared state and the initial state are.Our results show that the fidelity is a function of thedecoherence rates and the angles of the initial state.It is found that for each of the two RSP schemes,the influence ofthe noise acting simultaneously in x,y,and z directions on the average fidelity is the strongest while the influence of thenoise acting in x or z direction on the average fidelity is relatively weaker.

Deterministic remote state preparation of arbitrary three-qubit state through noisy cluster-GHZ channel

We propose a novel scheme for remote state preparation of an arbitrary three-qubit state with unit success probability,utilizing a nine-qubit cluster-GHZ state without introducing auxiliary qubits.Furthermore,we proceed to investigate the effects of different quantum noises(e.g.,amplitude-damping,phase-damping,bit-flip and phase-flip noises)on the systems.The fidelity results of three-qubit target state are presented,which are usually used to illustrate how close the output state is to the target state.To compare the different effects between the four common types of quantum noises,the fidelities under one specific identical target state are also calculated and discussed.It is found that the fidelity of the phase-flip noisy channel drops the fastest through the four types of noisy channels,while the fidelity is found to always maintain at 1 in bit-flip noisy channel.

Strong-Driving-Assisted Probabilistic State Preparation in Cavity QED

An alternative scheme is proposed for preparing the superpositions of coherent states with controllable weighting factors along a straight line for a cavity field. The scheme is based on the interaction of a single-mode cavity field with a resonant two-level atom driven by a strong classical field. It is in contrast to the previous methods used in cavity QED of injecting a coherent state into a cavity via a microwave source. In the scheme, the interaction between the cavity mode and atoms is fully resonant, thus the required interaction time is greatly shortened. Moreover, the present scheme requires smaller numbers of operations. In view of decoherence, a reduction of interaction time and numbers of operations for the state preparation is very important for experimental implementation of quantum state engineering.

Deterministic hierarchical joint remote state preparation with six-particle partially entangled state

In this paper, we present a novel scheme for hierarchical joint remote state preparation（HJRSP） in a deterministic manner, where two senders can jointly and remotely prepare an arbitrary single-qubit at three receivers＇ port. A six-particle partially entangled state is pre-shared as the quantum channel. There is a hierarchy among the receivers concerning their powers to reconstruct the target state. Due to various unitary operations and projective measurements, the unit success probability can always be achieved irrespective of the parameters of the pre-shared partially entangled state.

Quantum Remote State Preparation Based on Quantum Network Coding

As an innovative theory and technology,quantum network coding has become the research hotspot in quantum network communications.In this paper,a quantum remote state preparation scheme based on quantum network coding is proposed.Comparing with the general quantum remote state preparation schemes,our proposed scheme brings an arbitrary unknown quantum state finally prepared remotely through the quantum network,by designing the appropriate encoding and decoding steps for quantum network coding.What is worth mentioning,from the network model,this scheme is built on the quantum k-pair network which is the expansion of the typical bottleneck network—butterfly network.Accordingly,it can be treated as an efficient quantum network preparation scheme due to the characteristics of network coding,and it also makes the proposed scheme more applicable to the large-scale quantum networks.In addition,the fact of an arbitrary unknown quantum state remotely prepared means that the senders do not need to know the desired quantum state.Thus,the security of the proposed scheme is higher.Moreover,this scheme can always achieve the success probability of 1 and 1-max flow of value k.Thus,the communication efficiency of the proposed scheme is higher.Therefore,the proposed scheme turns out to be practicable,secure and efficient,which helps to effectively enrich the theory of quantum remote state preparation.

Comparison of differential evolution, particle swarm optimization,quantum-behaved particle swarm optimization, and quantum evolutionary algorithm for preparation of quantum states

Four intelligent optimization algorithms are compared by searching for control pulses to achieve the preparation of target quantum states for closed and open quantum systems, which include differential evolution(DE), particle swarm optimization(PSO), quantum-behaved particle swarm optimization(QPSO), and quantum evolutionary algorithm(QEA).We compare their control performance and point out their differences. By sampling and learning for uncertain quantum systems, the robustness of control pulses found by these four algorithms is also demonstrated and compared. The resulting research shows that the QPSO nearly outperforms the other three algorithms for all the performance criteria considered.This conclusion provides an important reference for solving complex quantum control problems by optimization algorithms and makes the QPSO be a powerful optimization tool.

Deterministic remote preparation of multi-qubit equatorial states through dissipative channels

We investigate the influence of a noisy environment on the remote preparation of the multi-qubit equatorial state, and specifically deduce the final states and fidelities of the remote preparation of the three-qubit and four-qubit equatorial states under diverse types of noisy environments, namely, amplitude damping, bit flip, phase damping, phase flip, bit-phase flip,depolarization, and non-Markov environments. The results show that when the decoherence factors of the front six noises are equal, the influence degrees of phase damped noise, bit flip noise, phase flip noise, and bit-phase flip noise are similar,while the information loss caused by the amplitude damped noise and depolarizing noise is less. In particular, the bit flip noise and depolarizing noise may have more complex effects on the remote state preparation(RSP) schemes depending on the phase information of the target states, even for the ideal cases where the fidelity values are always 1 for specific phase relations. In the non-Markov environment, owing to the back and forth of information between the environment and systems, fidelities exhibit oscillating behavior and the minimum value may stay greater than zero for a long evolutionary time. These results are expected to have potential applications for understanding and avoiding the influence of noise on remote quantum communication and quantum networks.

Probabilistic remote preparation of a two-atom entangled state

A scheme for remotely preparing a two-atom entangled state via entanglement swapping in cavity quantum electronic dynamics （QED） with the help of separate measurements is proposed. And the effect of cavity decay is eliminated in our scheme.

Remote preparation of an entangled two-qubit state with three parties

We present a scheme for probabilistic remote preparation of an entangled two-qubit state with three parties from a sender to either of two receivers. The quantum channel is composed of a paxtially entangled two-qubit state and a partially entangled three-qubit state. We calculate the successful total probabilities of the scheme in general and particular cases, respectively. We also calculate total classical communication cost in a general case and two particular cases, respectively.

Remote Preparation of a Two-Particle Entangled State by a Bipartite Entangled State and a Tripartite Entangled W State

We propose a scheme to remotely prepare a general two-particle entangled state by using a bipartite entangled state and a tripartite entangled W state as the quantum channel. Our scheme consists of one sender and two remote receivers. The sender can help either one of the receivers to remotely reconstruct the original state with the assistance of the other receiver＇s single-partlcle orthogona/measurement. We obtain the total success probability and discuss the classical communication cost in our remote state preparation scheme.