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arXiv:2407.03603

Deterministic entanglement swapping of W states

Sajede Harraz, Yueyan Wang, Shuang Cong

Published Jul 4, 2024• 0 citations
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Abstract

In this paper, we propose a deterministic entanglement swapping protocol for generating a shared three-qubit W state between two remote parties. Our method offers a reliable alternative to existing probabilistic protocols for W state entanglement swapping, which is crucial for various quantum information processing tasks. We present a detailed quantum circuit design, implemented using the Qiskit simulator, that outlines the preparation of W states and the execution of joint measurements required for the entanglement swapping process. Furthermore, we analyze the effects of imperfect operations and noisy communication channels on the fidelity of the resulting shared W state. To address these challenges, we introduce a weak measurement-based purification method that enhances fidelity in the presence of amplitude damping. Through mathematical analysis and Qiskit simulations, we demonstrate the effectiveness of our proposed protocol, offering a practical solution for high-fidelity W state generation in real-world quantum communication scenarios.

DOI
10.48550/arxiv.2407.03603

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In this paper, we propose a deterministic entanglement swapping protocol for generating a shared three-qubit W state between two remote parties. Our method offers a reliable alternative to existing probabilistic protocols for W state entanglement swapping, which is crucial for various quantum information processing tasks. We present a detailed quantum circuit design, implemented using the Qiskit simulator, that outlines the preparation of W states and the execution of joint measurements required for the entanglement swapping process. Furthermore, we analyze the effects of imperfect operations and noisy communication channels on the fidelity of the resulting shared W state. To address these challenges, we introduce a weak measurement-based purification method that enhances fidelity in the presence of amplitude damping. Through mathematical analysis and Qiskit simulations, we demonstrate the effectiveness of our proposed protocol, offering a practical solution for high-fidelity W state generation in real-world quantum communication scenarios.
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W states are a valuable resource for various quantum information tasks, and several protocols to generate them have been proposed and implemented.We introduce a quantum repeater protocol to efficiently distribute three-qubit W states over arbitrary distances in a two-dimensional triangular quantum network with polylogarithmic overhead, thereby enabling these applications between remote parties.The repeater protocol combines two ingredients that we establish: probabilistic entanglement swapping with three copies of three-qubit W states to a single long-distance three-qubit W state, and an improved entanglement purification protocol.The latter not only shows a better performance, but also an enlarged purification regime as compared to previous approaches.We show that the repeater protocol allows one to deal with errors resulting from imperfect channels or state preparation, and noisy operations, and we analyze error thresholds, achievable fidelities, and overheads.
Quantum entanglement plays an irreplaceable role in various remote quantum information processing tasks. Here we present protocols for generating deterministic and heralded NNN-qubit entangled states across multiple network nodes. By utilizing a pre-shared maximally entangled state and single-qubit operations within an indefinite causal order framework, the multi-qubit entangled state between distant parties can be generated deterministically. The complex entangled state measurements and multiple pre-shared entangled states, are essential in conventional entanglement swapping technique, but are not required in our approach. This greatly reduces the complexity of the quantum circuit and makes it more experimentally feasible. Furthermore, we develop optical architectures to implement these protocols by encoding qubits in polarization degree of freedom. The results indicate that our protocols significantly improve the efficiency of long-distance entanglement generation and provide a practical framework for establishing large-scale quantum networks.
Abstract Joint remote state preparation (JRSP) has gained much attention since its first appearance. However, almost all the proposals have focused on the JRSP of pure states. In this paper, we present a scheme of JRSP for mixed states via the three-qubit GHZ state. The scheme is deterministic for real coefficient mixed states and probabilistic for complex ones. The corresponding quantum circuits are given for the deterministic JRSP schemes. The model of the deterministic JRSP scheme is introduced in the language of density operators. Furthermore, we investigate the efficiency of deterministic JRSP when some qubits in the protocol are subjected to a noisy environment. Four types of noise usually encountered in quantum communication are considered, i.e. the bit-flip, phase-flip (phase-damping), depolarizing and amplitude-damping noise. We find that the fidelity is affected by both coefficients of the target mixed state and noise parameter of the channel. Specifically, the fidelity decreases with the purity parameter in the presence of noise.
In this paper, we discuss a protocol for preparing a non-maximally entangled W-state at a distant location where there are two parties intending such creation each of whom possesses only partial information about the state. These two parties along with a third party Controller, participate in a single protocol in order to create the intended state in the hands of a fourth party. The role of the controller is to fabricate an 8-qubit entangled state and distribute the respective qubits involved in the entangled state to the relevant parties and thereby creating a noisy quantum channel. The protocol is first ideally discussed in the noise-free case which is then a perfect joint remote state preparation protocol with fidelity 1. Then, we discuss the performance of the protocol in the presence of noise in which the fidelity is diminished. We consider three different types of noises and analyze the variation of fidelity of the process.
Abstract It is a significant subject to explore effective quantum communication protocol and enhance the efficiency of the transmission process in noisy environments. In this paper, we investigate the bidirectional controlled remote preparation of an arbitrary single-qubit state in the presence of dissipative environments by using two EPR states as the entanglement source. We first construct the quantum circuit of our scheme by means of unitary matrix decomposition procedure, then the effects of the Markovian and non-Markovian environmental noises acting on the EPR states are considered through the analytical derivation and numerical calculations of the corresponding average fidelity. Moreover, we adopt two methods of weak measurement reversal (WMR) and detuning modulation to improve the average fidelity. Our results show that the average fidelity can be remarkably enhanced under appropriate conditions of the WMR strength and the detuning. Compared with the average fidelity behaviors in dissipative environments, it is also shown that the two methods for fidelity improvement are more efficient in the non-Markovian regime than in the Markovian regime.