Entanglement Swapping Research Articles

Entanglement swapping via lossy channels using photon-number-encoded states

Entanglement swapping via lossy channels using photon-number-encoded states

Research on Intraparticle to Interparticle Entanglement Swapping Protocols

Entanglement is one of the most striking features of quantum systems, whereby its non-classical correlation is an essential resource in numerous quantum protocols. Entanglement can be divided into two categories: interparticle and intraparticle entanglement. There are both distinctions and similarities between these two kinds of entangled states. This work delves into these distinctions and similarities from the following aspects: correlation and non-locality, robustness, the mechanisms of generation and separation, and practical applications. Entanglement swapping is a technique based on quantum entanglement. As entanglement has different categories, entanglement swapping also has various types, including interparticle to interparticle and intraparticle to interparticle. Swapping protocols from intraparticle entanglement to interparticle entanglement can be applied to super quantum dense encoding, quantum information transmission, quantum teleportation, etc. Thus, this work proposes three swapping protocols, from spin–orbit intraparticle entanglement to spin–spin interparticle entanglement, based on Bell state joint measurement, the cross-Kerr medium, and linear optical elements. This work can help us better understand entanglement by analyzing the differences and similarities between the two types of entangled states. It can also enhance entanglement swapping protocols, from spin–orbit intraparticle to spin–spin interparticle entanglement, for use in quantum information transfer.

Enhancing Quantum Key Distribution Protocols for Extended Range and Reduced Error

Abstract this paper proposes an optimized Quantum Key Distribution (QKD) protocol using entanglement swapping techniques to extend transmission range and improve error correction. Additionally, integrates an advanced error correction technique which is Low Density Parity Check (LDPC) and multi-hop quantum repeaters for more enhancement of the protocol performance. Hybrid Quantum Classical Error Correction Methods is applied ensuring compatibility and optimal performance and to manage the increased complexity. Simulations prove that 25% improvement in transmission distance with entanglement swapping. 50% improvement with advanced error correction and a 100% improvement with multi-hop quantum repeaters compared to existing protocols. These discoveries are supported by both theoretical analysis and simulation results, indicating significant decreases in error rates and extensions in maximum transmission distances. Comparative analysis made with existing protocols and that demonstrated the superiority of proposed approach in terms of extended secure communication distance, higher key generation rate and improved resilience to attacks.

Entanglement swapping in generalized probabilistic theories and iterated Clauser-Horne-Shimony-Holt games

Entanglement swapping in generalized probabilistic theories and iterated Clauser-Horne-Shimony-Holt games

Energetic cost as a consequence of parallel transporting speed limit

Time-optimal unitary operating quantum systems and energy-efficient quantum gates are vital in quantum engineering. Here, we establish the connection between the energetic cost and the quantum speed limit for parallel evolving of a quantum system. Our results show that the energetic cost is the consequence of parallel transporting speed limit, which opens up the critical role of parallel transport of the quantum state for the quantum technologies such as the quantum simulation, the quantum information processing. Our investigations present a route to construct the energetic-efficient quantum gate. In addition, our theoretical framework provides an alternative method for calculating quantum speed limit. Two typical relevant systems are employed to illustrate our results: the spin-1/2 particle in the rotating magnetic field and the entanglement swap gate.

Authenticated multi-party quantum key agreement protocol based on cluster states

Quantum key agreement (QKA) is an important cryptographic primitive that plays a pivotal role in private communications. Authenticated QKA plays an important role in QKA. In this paper, we propose an authenticated multiparty QKA scheme based on 4-qubit cluster states entanglement swapping. The scheme is divided into two parts, the first part is the quantum identity authentication stage, and the second part is the QKA stage. In the quantum identity authentication stage, the participants determine that the participant communicating with them is the claimed person through mutual authentication, which can avoid the impersonation attack of the eavesdropper Eve. In the QKA phase, the participants adopt a bidirectional transmission structure with the participation of a semi-trusted third party, and based on the entanglement swapping property of the 4-qubit cluster state, the QKA is finally realized. Detailed security analysis shows that the protocol can resist a variety of internal and external attacks, such as participants attack, entangle-measure attack, and so on.

Optimal routing and end-to-end entanglement distribution in quantum networks

Quantum networks are designed to transmit quantum bits (qubits) among quantum devices to enable new network resources for the applications. Entanglement distribution and entanglement swapping are fundamental procedures that are required in several network operations. However, they are probabilistic operations, which can lead to severe network performance degradation. This article investigates the engineering problem of resource allocation in quantum networks, considering factors like entanglement distribution probability, quantum memory characteristics, and fidelity. We model this as an optimization model to obtain an optimal solution. In particular, we formulate an integer linear programming (ILP) and develop a heuristic algorithm, aiming to minimize the number of required entangled qubit pairs (Bell pairs or EPR pairs) in any adjacent pair in the quantum network. Extensive simulations are performed to compare the performance of proposed ILP and heuristic. In all the cases, the heuristic produces a comparable solution to the optimal one. Simulation results ensure that the value of maximum utilized Bell pairs in a quantum network highly depends on the value of the probability of entangled pairs established, considering the time in the quantum memory besides the number of incoming requests.

Quantum correlation swapping between Bell-diagonal states

Quantum correlation (QC) swapping is a generalization of quantum entanglement swapping, in which the concerned QCs can be quantum entanglement, QC beyond quantum entanglement, or both of them. In general, QC swapping is different from quantum entanglement swapping. Obviously, the study range of the former is beyond than the latter, and the former can give more interesting and significant applications in quantum information processings. So far, QC swapping has been studied explicitly only for a rather limited set of two-qubit quantum states as the initial states and cases for more general QC swapping with multi-parameter initial states are not known. In this article, we explore the QC swapping case with three-parameter Bell-diagonal (BD) states as the initial states. The familiar QC measure, quantum discord (Ollivier and Zurek 2001 Phys. Rev. Lett. 88 017901), is utilized to quantify all the QCs in the concerned states. It is found that a long-distance shared QC can be acquired through the BD-initial states case of QC swapping. Moreover, some distinct features and characteristics can be exposed.

Reducing hardware requirements for entanglement distribution via joint hardware-protocol optimization

We conduct a numerical investigation of fiber-based entanglement distribution over distances of up to 1600 km using a chain of processing-node quantum repeaters. We determine minimal hardware requirements while simultaneously optimizing over protocols for entanglement generation and entanglement purification, as well as over strategies for entanglement swapping. Notably, we discover that through an adequate choice of protocols the hardware improvement cost scales linearly with the distance covered. Our results highlight the crucial role of good protocol choices in significantly reducing hardware requirements, such as employing purification to meet high-fidelity targets and adopting a swap as soon as possible policy for faster rates. To carry out this analysis, we employ an extensive simulation framework implemented with NetSquid, a discrete-event-based quantum-network simulator, and a genetic-algorithm-based optimization methodology to determine minimal hardware requirements.

A quantum secure multi-party summation protocol with quantum Fourier transform

In this paper, a quantum secure multi-party summation scheme with a third party based on quantum Fourier transform (QFT) is put forward, where the third party cannot be permitted to cooperate with others but is allowed for all kinds of attacks. Under the help of third party, [Formula: see text] users can calculate the addition modulo [Formula: see text] of their private integer strings. The third party generates two-level single qubit and its product state as the initial quantum resource, produces the traveling particles with QFT and the controlled-not (CNOT) operations, and sends the traveling particles out to the first users; then, [Formula: see text] users encode their private integer sequences by performing the phase shifting operations on the travelling particles one after another; and finally, the third party decodes out the summation of the private integer sequences from [Formula: see text] users through CNOT operations and inverse quantum Fourier transform (IQFT). This protocol only adopts two-level single particle state and its product state as initial quantum resource, only needs [Formula: see text]-level single particle measurement and does not need to perform quantum entanglement swapping. Security analysis indicates that this protocol can overcome not only the outside attack but also the participant attack.

Authenticated quantum key agreement based on cluster states against collective noise

Quantum key agreement (QKA) is an important branch of quantum cryptography. Particles are easily affected by noise in quantum channel transmission, which provides a cover for eavesdropper Eve to attack maliciously and eventually leads to the protocol failure. In this paper, based on the properties of four-particle cluster states and their entanglement swapping, two authenticated two-party QKA protocols that can resist collective noise (collective-dephasing noise and collective-rotation noise) by using CZ, CNOT, and Pauli operations are designed, respectively. Besides, both parties can authenticate each other’s identities, which makes our protocol more secure. In addition, security analysis shows that these two protocols can resist various attacks from inside and outside, such as participant attacks and entangle-measure attacks.

Large teleportation of two-qubit state between non-neighboring nodes based on the utilization of multiple cluster states within quantum networks

The transmission of quantum states over extended distances is constrained by photon losses, ruling out direct amplification akin to classical telecommunications due to the non-cloning theorem. Overcoming this challenge involves implementing quantum repeater protocols that leverage entanglement swapping to create long-distance entanglement from shorter distances. A novel multi-hop quantum teleportation scheme, blending concepts from quantum repeaters and teleportation, is under exploration. It aims to transfer arbitrary two-qubit states between two distant parties, even in the absence of a direct quantum channel. Intermediate nodes, connected via a four-qubit entangled cluster state as quantum channels, are introduced based on a more general routing protocol. Bell measurements are independently conducted by the source node (Alice) and all intermediate nodes, with simultaneous transmission of measurement results, significantly reducing time consumption. Determining the quantum state from Bell measurement results requires only the destination node (Bob) for a simple unitary transformation. Moreover, this protocol holds promise for implementation on the IBM Quantum Experience platform once the requisite quantum circuits are designed. This overview encompasses both the theoretical and simulated status of the proposed scheme, with simulated findings incorporated into quantum state tomography to verify the accuracy of the transmitted quantum state.

Teleportation of Multiparticle Entangled States

This paper investigates the theoretical basis and actual methods for teleporting entangled states using multiple particles. Beginning with Bennett et al.'s pioneering work in 1993, which established the notion of quantum teleportation. In this paper, I will discuss the quantum teleportation, quantum entanglement, Entanglement schemes such as Entanglement swapping scheme and will find out the rate of successful teleportation in terms of fidelity. Additionally discussed is minimal assured fidelity, which is the lowest level of fidelity for any unknown quantum information about the states[1]. Additionally, the success rate of teleporting a superposition of odd and even coherent states is demonstrated to be able to be raised from 50% to almost 99%[2]. We discover that by just isolating the vacuum state from the even state, it can virtually transport, divert, and exchange. Key Words: Entanglement, Quantum teleportation, Entanglement swapping scheme, Bell state measurement (BSM), Quantum information.

Flexible Quantum Network Coding by Using Quantum Multiplexing

AbstractQuantum network coding (QNC) aims at alleviating quantum communication congestion in quantum networks. Although several QNC protocols have been presented, they cannot meet the practical requirements that part of source nodes intend to transmit their quantum states with same or different qubit numbers via the bottleneck network simultaneously. Here, the study presents a flexible QNC protocol by using quantum multiplexing. First, the entangled pairs are generated between adjacent nodes in a heralded way by using quantum multiplexing. Then the quantum memories of the source nodes and the ones of the corresponding target nodes are entangled when the intermediate nodes execute multiple rounds of entanglement swapping operations on their quantum memories. Finally, the quantum states are transmitted from the source nodes to their corresponding target nodes by means of quantum teleportation. Compared with the existing protocols, the protocol allows an arbitrary part of the source nodes to transmit their quantum states with same or different qubit numbers via the bottleneck network simultaneously, thereby exhibiting its flexibility.

Bidirectional Quantum Teleportation of GHZ and EPR States Through Entanglement Swapping Utilizing a Pre-established GHZ Channel

Bidirectional Quantum Teleportation of GHZ and EPR States Through Entanglement Swapping Utilizing a Pre-established GHZ Channel

Low-cost nonlocal Toffoli gate in a linear quantum network topology

Although a Toffoli gate can be equivalently implemented using several single-qubit and two-qubit gates, it will consume much resource, two of which are nonlocal controlled-NOT (CNOT) gates acting on two non-adjacent nodes, especially in distributed quantum computation (DQC). We, for the first time, employ an ancillary qubit to construct a nonlocal Toffoli gate for DQC in linear network topology. The ancillary-qubit-based scheme needs fewer qubits, quantum gates, and entanglement states than that based on quantum teleportation scheme and the entanglement swapping scheme. We also analyze the performance of the three proposed schemes under different application scenarios, and present their pros and cons. Our work will help to implement DQC in noisy intermediate-scale quantum (NISQ) era.

SkySwapping: Entanglement resupply by separating quantum swapping and photon exchange

We propose a fast, satellite-based, on-demand entanglement resupply protocol which leverages entangled pairs exchanged in advance between satellites and ground stations. At the request time, the protocol does not require any quantum information exchange between ground and satellite, by performing the quantum entanglement swapping on satellite-level only, thus separating the particle exchange phase. In this work we analyzed different recent approaches on the topic of satellite-based entanglement resupply and our protocol improves existing works by minimizing fidelity loss due to environmental factors regardless of the distance between requesting ground stations.

Statistical properties and repetition rates for a quantum network with geographical distribution of nodes

Steady technological advances and recent milestones such as intercontinental quantum communication and the first implementation of medium-scale quantum networks are paving the way for the establishment of the quantum internet, a network of nodes interconnected by quantum channels. Here we build upon recent models for quantum networks based on optical fibers by considering the effect of a non-uniform distribution of nodes, more specifically based on the demographic data of the federal states in Brazil. We not only compute the statistical properties of this more realistic network, comparing its features with previous models but also employ it to compute the repetition rates for entanglement swapping, an essential protocol for quantum communication based on quantum repeaters.

Heralded Entanglement Distribution Between Two Spin‐Wave Memories Using Temporally Multiplexed Scheme

AbstractThe elementary link, which is formed by entanglement between two remote atomic ensembles, is a fundamental component of Duan–Lukin–Cirac–Zoller (DLCZ) quantum repeater. For practical realization of quantum repeaters, it is required that entanglement between two atomic‐ensemble‐based memories can be generated with high rates and retrieved with high efficiencies. However, so far, such quantum‐repeater links remain challenge in experiments. Here, heralded entanglement distribution between atomic‐ensemble‐based memories is demonstrated via temporally multiplexed scheme. A train of 12 write pulses in time is applied to a cloud of cold atoms along different directions, which generates temporally multiplexed pairs of Stokes photons and spin waves via DLCZ processes. The Stokes fields propagating in the two spatial modes, which are paired with two spin waves are combined to perform a single‐photon Bell‐state measurement. A successful detection projects the two spin waves into a single‐excitation entanglement, which represents entanglement distribution in an elementary link. Compared with single‐mode storage scheme, the temporally multiplexed scheme gives rise to a 11.8‐fold increase in entanglement generation rate. By using cavity‐enhanced scheme, spin waves stored in the atoms are retrieved on demand and the retrieval efficiencies are up to 70%, which is beneficial for the subsequent entanglement swapping between adjacent links.

Hybrid protocols for multi-party semiquantum private comparison, multiplication and summation without a pre-shared key based on d-dimensional single-particle states

In this paper, by utilizing d-dimensional single-particle states, three semiquantum cryptography protocols, i.e., the multi-party semiquantum private comparison (MSQPC) protocol, the multi-party semiquantum multiplication (MSQM) protocol and the multi-party semiquantum summation (MSQS) protocol, can be achieved simultaneously under the assistance of two semi-honest quantum third parties (TPs). Here, the proposed MSQPC scheme is the only protocol which is devoted to judging the size relationship of secret integers from more than two semiquantum participants without a pre-shared key. And the proposed MSQM protocol absorbs the innovative concept of semiquantumness into quantum multiplication for the first time, which can calculate the modulo d multiplication of private inputs from more than two semiquantum users. As for the proposed MSQS protocol, it is the only semiquantum summation protocol which aims to accomplish the modulo d addition of more than three semiquantum users’ private integers. Neither quantum entanglement swapping nor unitary operations are necessary in the three proposed protocols. The security analysis verifies in detail that both the external attacks and the internal attacks can be resisted in the three proposed protocols.