Quantum teleportation, the process by which Alice can transfer an unknown quantum state to Bob by using preshared entanglement and classical communication, is one of the cornerstones of quantum information. The standard benchmark for certifying quantum teleportation consists in surpassing the maximum average fidelity between the teleported and the target states that can be achieved classically. According to this figure of merit, not all entangled states are useful for teleportation. Here we propose a new benchmark that uses the full information available in a teleportation experiment and prove that all entangled states can implement a quantum channel which cannot be reproduced classically. We introduce the idea of nonclassical teleportation witness to certify if a teleportation experiment is genuinely quantum and discuss how to quantify this phenomenon. Our work provides new techniques for studying teleportation that can be immediately applied to certify the quality of quantum technologies.
Quantum teleportation, the process by which Alice can transfer an unknown quantum state to Bob by using preshared entanglement and classical communication, is one of the cornerstones of quantum information. The standard benchmark for certifying quantum teleportation consists in surpassing the maximum average fidelity between the teleported and the target states that can be achieved classically. According to this figure of merit, not all entangled states are useful for teleportation. Here we propose a new benchmark that uses the full information available in a teleportation experiment and prove that all entangled states can implement a quantum channel which cannot be reproduced classically. We introduce the idea of nonclassical teleportation witness to certify if a teleportation experiment is genuinely quantum and discuss how to quantify this phenomenon. Our work provides new techniques for studying teleportation that can be immediately applied to certify the quality of quantum technologies.
Quantum teleportation establishes a correspondence between an entangled state shared by two separate parties that can communicate classically and the presence of a quantum channel connecting the two parties. The standard benchmark for quantum teleportation, based on the average fidelity between the input and output states, indicates that some entangled states do not lead to channels which can be certified to be quantum. It was recently shown that if one considers a finer-grained witness, then all entangled states can be certified to produce a nonclassical teleportation channel. Here we experimentally demonstrate a complete characterization of a new family of such witnesses, of the type proposed in Phys. Rev. Lett. 119, 110501 (2017)PRLTAO0031-900710.1103/PhysRevLett.119.110501 under different conditions of noise. We report nonclassical teleportation using quantum states that cannot achieve average fidelity of teleportation above the classical limit. We further use the violation of these witnesses to estimate the negativity of the shared state. Our results have fundamental implications in quantum information protocols and may also lead to new applications and quality certification of quantum technologies.
Quantum teleportation, a cornerstone of quantum information science, allows for the transfer of an unknown quantum state from a sender (Alice) to a receiver (Bob) using a shared entangled resource and classical communication. A fundamental challenge arises when the state to be teleported is unclonable, as dictated by the no-cloning theorem, precluding direct comparison between the initial and teleported states for certification. This paper proposes a robust Bell-certification scheme for validating the successful teleportation of such unclonable quantum states. We move beyond conventional fidelity benchmarks, which prove insufficient for unknown states, by focusing on the integrity of the Bell state entanglement and the correctness of the Bell measurement performed by Alice. Our methodology leverages the inherent properties of maximally entangled Bell states as the resource, combined with a verifiable Bell measurement analysis and a rigorous assessment of the classical communication channel. We detail how the quality of the shared entangled pair, potentially characterized by entanglement witnesses or purity measures, directly contributes to the certification of the teleportation process. Furthermore, we analyze the scheme's resilience to common noise models, such as depolarizing channels affecting the resource state, demonstrating how fluctuations in resource entanglement propagate to the certification confidence. The proposed Bell-certification provides a crucial framework for ensuring the reliability of quantum teleportation protocols in practical applications where direct state verification is impossible or impractical, paving the way for more secure and verifiable quantum communication and computation architectures.
The standard benchmark for teleportation is the average fidelity of teleportation and according to this benchmark not all states are useful for teleportation.It was recently shown, however, that all entangled states lead to nonclassical teleportation, with there being no classical scheme able to reproduce the states teleported to Bob.Here we study the operational significance of this result.On the one hand, we demonstrate that every state is useful for teleportation if a generalization of the average fidelity of teleportation is considered which concerns teleporting quantum correlations.On the other hand, we show the strength of a particular entangled state and entangled measurement for teleportation-as quantified by the robustness of teleportation-precisely characterizes their ability to offer an advantage in the task of subchannel discrimination with side information.This connection allows us to prove that every entangled state outperforms all separable states when acting as a quantum memory in this discrimination task.Finally, within the context of a resource theory of teleportation, we show that the two operational tasks considered provide complete sets of monotones for two partial orders based on the notion of teleportation simulation, one classical and one quantum.
An unknown quantum state can be teleported by using quantum measurements and the maximally entangled Einstein-Podolsky-Rosen (EPR) pair. It is well known that the usual nonclassical teleportation that cannot be simulated by the seminal classical measure-prepare strategy can be demonstrated with all entangled states. Herein, we propose a benchmark which reveals that not all such nonclassical teleportations are truly quantum mechanical. Rather, there exists a more robust classical-teleportation model, which includes the measure-prepare mimicry as a special case, that can describe certain nonclassical teleportations. Invalidating such a general classical model indicates genuine quantum teleportation wherein both the pair state and the measurement are truly quantum mechanical. We prove that EPR steering empowers genuine quantum teleportations, rather than entanglement. The benchmark can be readily used in practical experiments for ensuring that genuine quantum teleportation is implemented. The results presented herein provide strict criteria for implementing quantum-information processing where genuine quantum teleportation is indispensable.
Quantum teleportation, a cornerstone of quantum information science, enables the transfer of an unknown quantum state from a sender (Alice) to a receiver (Bob) using entanglement and classical communication. A fundamental principle of quantum mechanics, the no-cloning theorem, dictates that an arbitrary unknown quantum state cannot be perfectly duplicated. This paper introduces the concept of Bell-Certified Unclonable Teleportation, a novel protocol designed to intrinsically integrate the verification of entanglement quality and the preservation of unclonability within the teleportation process itself. By leveraging the unique properties of Bell states and their measurements, this protocol aims to provide a certification mechanism that assures both the successful transfer of the quantum state and the impossibility of its unauthorized replication during or after transmission. We explore how Bell state analysis, coupled with specific classical communication strategies, can serve as a robust signature for the integrity and security of the teleported state, thereby enhancing the trustworthiness of quantum communication channels. The proposed scheme offers a theoretical framework for building more secure and verifiable quantum communication primitives, addressing critical concerns in quantum cryptography and the future development of quantum networks.
Quantum teleportation, a cornerstone of quantum information science, enables the transfer of an unknown quantum state from one location to another without physically moving the state itself. Its efficacy is primarily quantified by fidelity, a measure of how closely the teleported state resembles the original. Achieving high-fidelity teleportation is paramount for practical applications in quantum communication and computation. This paper explores the intricate relationship between non-locality, the no-cloning theorem, and the pursuit of high-fidelity quantum teleportation. We introduce the concept of "unclonable non-locality" to describe scenarios where the inherent non-local correlations of entangled states are leveraged in a manner that inherently resists illicit copying, thereby enhancing the integrity and security of the teleportation process. We review current state-of-the-art teleportation protocols, analyzing their fidelity limitations and the impact of various noise models, such as those arising from Bell-diagonal resource states and local amplitude-damping channels. Our framework emphasizes that protocols exhibiting identical average fidelities can conceal distinct statistical behaviors and asymmetries introduced by local noise, stressing the need for a comprehensive statistical assessment beyond simple average fidelity. We propose methods for constructing and utilizing entangled resources that maximize non-local correlations while inherently enforcing the no-cloning principle, thereby offering a robust pathway to deterministic, high-fidelity quantum state transfer. The discussion highlights the potential for designing tailored teleportation benchmarks based on prior importance functions, unifying moment-based criteria and threshold-based success probabilities into a single figure of merit, and clarifying the role of entanglement strength in certifying high-fidelity teleportation. We also acknowledge the ethical implications associated with the development of powerful quantum technologies that could have significant societal impacts.