Teleportation with an imperfect state

Yongjian Gu, Chunmei Yao, Zheng-Wei Zhou +1 more

Noisy entangled resource and non-standard teleportation operations result in imperfect teleportation. In this paper, we derive an explicit expression for the output states of imperfect teleportation processes, thereby establishing a correspondence between teleportation and quantum channels. This result offers a different insight into teleportation. Also, it enables us to derive an expression for the fidelity of teleportation. Our results analytically reveal the dependence of the output states and the fidelity on the entangled resource and teleportation operations. The Nielsen–Caves teleportation formalism is used in the derivation.

Eduardo Kac

Pablo Sala, Sara Murciano, Yue Liu +1 more

Entanglement, measurement, and classical communication together enable teleportation of quantum states between distant parties, in principle, with perfect fidelity. To what extent do correlations and entanglement of a many-body wave function transfer under teleportation protocols? We address this question for the case of an imperfectly teleported quantum critical wave function, focusing on the ground state of a critical Ising chain. We demonstrate that imperfections, e.g., in the entangling gate adopted for a given protocol, effectively manifest as weak measurements acting on the otherwise pristinely teleported critical state. Armed with this perspective, we leverage and further develop the theory of measurement-altered quantum criticality to quantify the resilience of critical-state teleportation. We identify classes of teleportation protocols for which imperfection (i) preserves both the universal long-range entanglement and correlations of the original quantum critical state, (ii) weakly modifies these quantities away from their universal values, and (iii) obliterates long-range entanglement altogether while preserving power-law correlations, albeit with a new set of exponents. We also show that mixed states describing the average over a series of sequential imperfect teleportation events retain pristine power-law correlations due to a “built-in” decoding algorithm, though their entanglement structure measured by the negativity depends on errors similarly to individual protocol runs. These results may allow one to design teleportation protocols that optimize against errors—highlighting a potential practical application of measurement-altered criticality. Published by the American Physical Society 2024

Muhammad Taufiqi, Agus Purwanto, Lila Yuwana +4 more

Abstract An asymmetric bidirectional quantum controlled teleportation via a seven-qubit Werner-like mixed state is proposed. In the process of teleportation preparation, it is hypothesized that three imperfections could appear, namely (i) imperfection of the entangler device that may result in a non-maximal entanglement of the channel, (ii) local noises are introduced during the channel preparation process, and (iii) global noises occur during the channel state distribution to the corresponding parties. The local and global noises are selected as depolarizing noise with certain probability of transforming any entangled state into a maximally mixed state, resulting in a seven-qubit Werner-like mixed state. The teleportation fidelity with the presence of the imperfections is evaluated. It is shown that the teleportation is more robust under the presence of global noise compared to local noise.

Xihan Li, Fu‐Guo Deng