Joint Remote State Preparation Schemes for Two Different Quantum States Selectively

We present a scheme for joint remote state preparation (JRSP) of three-particle state via three tripartite Greenberger–Horne–Zeilinger (GHZ) entangled states as the quantum channel linking the parties. We use eight-qubit mutually orthogonal basis vector as measurement point of departure. The likelihood of success for this scheme has been found to be [Formula: see text]. However, by putting some special cases into consideration, the chances can be ameliorated to [Formula: see text] and 1. The effects of amplitude-damping noise, phase-damping noise and depolarizing noise on this scheme have been scrutinized and the analytical derivations of fidelities for the quantum noisy channels have been presented. We found that for [Formula: see text], the states conveyed through depolarizing channel lose more information than phase-damping channel while the information loss through amplitude damping channel is most minimal.

We present a scheme for optimal joint remote state preparation of two-qubit equatorial states. Our protocol improves on a previous scheme (Choudhury and Dhara in Quantum Inf Process 14:373---379, 2015) that had a success probability of 25 %, which increased to 50 % when extra classical information is sent to the receiver. We show that using our modified scheme, the desired state can be prepared deterministically with the same quantum channel. Moreover, we generalize the scheme to prepare N-qubit equatorial states in which the receiver can reconstruct the original state with 100 % success probability.

In this paper, we first propose a remote state preparation (RSP) scheme in the traditional sense, which accomplishes the remote preparation of a single-qubit controlled by multiple agents in the network. This triggers a new RSP scheme, by which we can remotely prepare tensor product-type quantum states controlled by one agent. After that, we generalize the above approach to the RSP scheme of multi-qubit information controlled by multiple agents in the network. In the extended scheme, as long as all agents operate faithfully, the receiver can recover all qubits of information in the original state; otherwise, the scheme fails. Such a scheme entangles quantum information in the preparation process, thus slashing the cost of such quantum resources as auxiliary qubits and local unitary operations, and, meanwhile, reducing the number of classical bits transferred among participants. Finally, we further investigate the remote preparation scheme for multiple qubit-string information under the control of multiple agents in the network.

We present a novel scheme for bidirectional controlled remote state preparation (BCRSP) in a three-dimensional system with a six-qutrit entangled state as the quantum channel. In this scheme, two distant parties, Alice and Bob, are not only senders but also receivers. Alice wants to remotely prepare a single-qutrit equatorial state at Bob’s site, while at the same time, Bob wishes to help Alice by remotely preparing another single-qutrit equatorial state. It is shown that, only if the two senders and the controller collaborate with each other, the BCRSP can be completed successfully.

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.

Using partial entangled states as the quantum channel, two schemes for probabilistic remote preparation of the four-particle cluster-type state with real and complex coefficients are presented. In the first scheme, the sender and the receiver share two partial Bell states and one partial three-qubit GHZ stats as the quantum channel, and the sender can help a remote receiver to prepare a four-particle entangled cluster-type state by using three-qubit projective measurements with certain probability. In the second scheme, the quantum channel is composed of two partial three-qubit GHZ states, the remote state preparation (RSP) can be successfully realized via the positive operator valued measure (POVM), and the two-particle projective measurements are also needed in this process. The total success probability and classical communication cost are calculated.

In this paper, the technique of weak measurement is employed in order to enhance the fidelity of joint remote state preparation (JRSP) protocol under decoherence. We design a quantum circuit of joint remote preparation of a single-qubit state through a GHZ state. Then, we analytically derive the average fidelity of the JRSP protocol under four types of noise usually encountered in real-world implementations of quantum communication protocols, i.e. the phase-flip, depolarizing, amplitude-damping and bit-flip noise. Our study shows that the application of weak measurement and measurement reversal could enhance the average fidelity of the JRSP process under the influence of phase-flip, depolarizing, amplitude-damping noise for most values of the decoherence parameters. If the JRSP process suffers from the bit-flip noise, the weak measurement technique is not useful for increasing the average fidelity.

We propose two controlled remote state preparation protocols via partially entangled channels. One prepares a single-qubit state, and the other prepares a two-qubit state. Different from other controlled remote state preparation schemes which also utilize partially entangled channels, neither auxiliary qubits nor two-qubit unitary transformations are required in our schemes, and the success probabilities are independent of the coefficients of the quantum channel. The success probabilities are 50 and 25 % for arbitrary single-qubit states and two-qubit states, respectively. We also show that the success probabilities can reach 100 % for restricted classes of states.

Artificial intelligence and quantum communication are two distinct but very far-reaching disciplines. In recent years, with the rapid development of these two disciplines, using artificial intelligence to solve the problem of transmission quality in quantum communication is also a hotspot of scientific research. In this paper, we propose the scheme for asymmetric controlled cyclic joint remote state preparation scheme in noisy environments to lay the foundation for the future use of artificial intelligence to solve the noise problem in the quantum communication process. In the scheme, under the control of supervisor David, several senders can jointly realize the preparation of quantum states for the remote receiver. We first performed the theoretical analysis of the scheme in the ideal environment, then studied the scheme in four different noise environments (amplitude damping noise, phase damping noise, bit-flip noise, depolarized noise). The results show that except in the bit-flip noise environment, the fidelity of the output state is only related to the decoherence rate, and in the other three noise environments, the fidelity is not only related to the decoherence rate but also the coefficients of the desired state. Finally, we also compared our scheme with other remote state preparation schemes, and the results show that our scheme has some superiority.

We propose two novel schemes for multicast-based remote preparation of two kinds of two-qubit states with the aid of the eight-qubit entangled states as the quantum channels. In our scenario, the different encoded information is transmitted synchronously from one sender to many spatially separated receivers. Moreover, it is shown that the first scheme is realized successfully and efficiently, and only the four-qubit projective measurement and appropriate local unitary operations are needed. In particular, the eight-qubit partially entangled channel is utilized in the second.

In quantum mechanics, the process of measurement is a subtle interplay between extraction of information and disturbance of the state of the quantum system. A quantum non-demolition (QND) measurement minimizes this disturbance by using a particular system - detector interaction which preserves the eigenstates of a suitable operator of the quantum system. This leads to an ideal projective measurement. We present experiments in which we perform two consecutive measurements on a quantum two -level system, a superconducting flux qubit, by probing the hysteretic behaviour of a coupled nonlinear resonator. The large correlation between the results of the two measurements demonstrates the QND nature of the readout method. The fact that a QND measurement is possible for superconducting qubits strengthens the notion that these fabricated mesoscopic systems are to be regarded as fundamental quantum objects. Our results are also relevant for quantum information processing, where projective measurements are used for protocols like state preparation and error correction.

One-qubit pure states, living on the surface of Bloch sphere, can be mapped onto the usual complex plane by using stereographic projection. In this paper, after reviewing the entanglement of two-qubit pure state, it is shown that the \emph{quaternionic} stereographic projection is related to concurrence measure. This is due to the fact that every two-qubit state, in ordinary complex field, corresponds to the one-qubit state in quaternionic skew field, called quaterbit. Like the one-qubit states in complex field, the stereographic projection maps every quaterbit onto a quaternion number whose complex and quaternionic parts are related to Schmidt and concurrence terms respectively. Rather, the same relation is established for three-qubit state under \emph{octonionic} stereographic projection which means that if the state is bi-separable then, quaternionic and octonionic terms vanish. Finally, we generalize recent consequences to $2 \otimes N$ and $4\otimes N$ dimensional Hilbert spaces ($N\geq 2$) and show that, after stereographic projection, the quaternionic and octonionic terms are entanglement sensitive. These trends are easily confirmed by direct computation for general multi-particle W- and GHZ-states.

In this paper, we develop a quantum communication protocol for the simultaneous preparation of a two-qubit and a three-qubit state at the positions of two different parties situated spatially apart. For one party, Alice, it is a remote state preparation of a known two-qubit state while for the other party, Bob, it is a joint remote state preparation with the help of a third party, Eve. The protocol is executed in a hybrid form bi-directionally in the presence of two controllers, Charlie and David. There is a hierarchy in the process through different levels of control under which the actions by Alice and Bob are performed. There is a need for a ten-qubit entangled channel connecting the five parties. The generation of this channel through a circuit is discussed. The protocol is executed on the IBM Quantum platform. We also study the effect of noise on our protocol. Here, amplitude-damping, bit-flip and phase-flip noisy environments are considered and the corresponding variations of fidelity are theoretically and numerically analyzed.

Optimizing scheme for probabilistic remote preparation of a two-qubit state

Effective propagation of information among multiple users is the purpose of realizing large-scale quantum communication networks. In this paper, multicast protocols for any single, two and three qubits with real amplitude and complex phase information are presented. They were realized using a composite of Greenberger–Horne–Zeilinger states as shared channels. Joint remote state preparation was the main method for completing quantum multicast. At the same time, quantum state tomography of the schemes was carried out on the IBM Quantum platform. The obtained states were compared with the target states by fidelity. The analysis of communication efficiency and noise effects shows that our protocol has advantages in the case of complex coefficients.