Recently it has been shown how the use of quantum entanglement can lead to the creation of real-time communication channels whose viability can be made location dependent. Such functionality leads to new security paradigms that are not possible in classical communication networks. Key to these new security paradigms are quantum protocols that can unconditionally determine that a receiver is in fact at an a priori assigned location. A limiting factor of such quantum protocols will be the decoherence of states held in quantum memory. Here we investigate the performance of quantum location verification protocols under decoherence effects. More specifically, we address the issue of how decoherence impacts the verification using N = 2 qubits entangled as Bell states, as compared to N >; 2 qubits entangled as GHZ states. We study the original quantum location verification protocol, as well as a variant protocol, introduced here, which utilizes teleportation. We find that the performance of quantum location verification is in fact similar for Bell states and some N >; 2 GHZ states, even though quantum decoherence degrades larger-qubit entanglements faster. Our results are important for the design and implementation of location-dependent communications in emerging quantum networks.
Recently it has been shown how the use of quantum entanglement can lead to the creation of real-time communication channels whose viability can be made location dependent. Such functionality leads to new security paradigms that are not possible in classical communication networks. Key to these new security paradigms are quantum protocols that can unconditionally determine that a receiver is in fact at an a priori assigned location. A limiting factor of such quantum protocols will be the decoherence of states held in quantum memory. Here we investigate the performance of quantum location verification protocols under decoherence effects. More specifically, we address the issue of how decoherence impacts the verification using N = 2 qubits entangled as Bell states, as compared to N >; 2 qubits entangled as GHZ states. We study the original quantum location verification protocol, as well as a variant protocol, introduced here, which utilizes teleportation. We find that the performance of quantum location verification is in fact similar for Bell states and some N >; 2 GHZ states, even though quantum decoherence degrades larger-qubit entanglements faster. Our results are important for the design and implementation of location-dependent communications in emerging quantum networks.
The ability to unconditionally verify the location of a communication receiver would lead to a wide range of new security paradigms. However, it is known that unconditional location verification in classical communication systems is impossible. In this work we show how unconditional location verification can be achieved with the use of quantum communication channels. Our verification remains unconditional irrespective of the number of receivers, computational capacity, or any other physical resource held by an adversary. Quantum location verification represents an application of quantum entanglement that delivers a feat not possible in the classical-only channel. It gives us the ability to deliver real-time communications viable only at specified geographical coordinates.
This work presents a simulation-based study of quantum teleportation for secure communication under ideal, noisy, and adversarial conditions using IBM’s Qiskit framework and the Qiskit Aer simulator. The study begins with the verification of Bell-state entanglement to establish quantum correlation, followed by the implementation of a standard three-qubit quantum teleportation protocol. The teleportation system is evaluated across four experimental scenarios: (i) ideal noiseless teleportation, (ii) depolarizing noise environments, (iii) basis disturbance attacks using unauthorized Hadamard operations, and (iv) entanglement injection attacks introducing an external qubit into the communication channel. Each scenario is analyzed using measurement statistics, probability distributions, and state behavior of the receiver qubit. The results demonstrate that quantum teleportation achieves high fidelity under ideal conditions, while environmental noise introduces statistical degradation in state reconstruction. Furthermore, adversarial interference significantly disrupts teleportation performance, with basis disturbance producing near-uniform probability distributions and entanglement injection altering receiver-side measurement statistics. This study highlights both the robustness and vulnerability of quantum communication protocols and emphasizes the importance of noise mitigation, entanglement security, and attack detection mechanisms in future quantum networking systems. The work is entirely simulation-based and implemented using Python and Qiskit.
Quantum entanglement-based networks enjoy extreme security due to quantum mechanics, but must distribute entanglement over communications channels that will introduce quantum decoherence processes. Quantum teleportation serves the fundamental mechanism in quantum entanglement networks, but involves two quantum channels going through different decoherence processes. This situation suggests imbalanced phase distortions due to different quantum decoherence processes in two channels, and consequently disrupt the normal operation of quantum teleportation and further entanglement swapping protocols. By modeling quantum decoherence in a quantum channel in terms of a unitary phase rotation, we analyze both quantum entanglement-based networking protocols that utilize Bell states and derive closed-form expressions for teleportation fidelity and the success probability of quantum swapping, a vital mechanism that facilitates quantum repeaters in quantum communication networks. We discover a simple, yet paramount result: operation performance depends on the mismatch between the two quantum channels by a pair of Bell-state particles, rather than the absolute phase distortions of each channel, which suggests the desirable factor of entanglement distribution in a quantum communication network and distributed quantum computing.
Position information underpins many modern technologies, from navigation and timing to authentication and critical infrastructure. However, classical methods of proving that information originates from a particular position are vulnerable to spoofing. This limitation can be overcome with quantum technologies but current protocols rely on trust in quantum hardware that can be undermined, or require quantum computers and bounds on adversarial computation. Nevertheless, there has been significant interest in experimental demonstrations, and aspects of these protocols have been implemented. Here we introduce and experimentally demonstrate the Bell-test quantum position verification protocol for device-independent quantum position verification that guarantees security with only observed correlations from a loophole-free Bell test across a quantum network. We experimentally implement a version of this device-independent protocol against adversaries who, before each trial, are weakly entangled. Our demonstration achieves a one-dimensional localization 2.47(2) times smaller than the best, necessarily non-remote, classical localization protocol. Compared to classical protocols with identical latencies, the localization volume is 4.53(5) times smaller, and represents a certifiable quantum advantage. The general Bell-test protocol is loss tolerant and secure against adversaries with significant quantum resources. This work allows digital security to be anchored to physically trusted locations, enabling new position-based authentication protocols for applications such as financial transactions, legal agreements, and securing critical infrastructure.
Abstract Quantum teleportation exemplifies how the transmission of quantum information starkly differs from that of classical information and serves as a key protocol for quantum communication and quantum computing. While an ideal teleportation protocol requires noiseless quantum channels to share a pure maximally entangled state, the reality is that shared entanglement is often severely degraded due to various decoherence mechanisms. Although the quantum noise induced by the decoherence is indeed a major obstacle to realizing a near-term quantum network or processor with a limited number of qubits, the methodologies considered thus far to address this issue are resource-intensive. Here, we demonstrate a protocol that allows optimal quantum teleportation via noisy quantum channels without additional qubit resources. By analyzing teleportation in the framework of generalized quantum measurement, we optimize the teleportation protocol for noisy quantum channels. In particular, we experimentally demonstrate that our protocol enables to teleport an unknown qubit even via a single copy of an entangled state under strong decoherence that would otherwise preclude any quantum operation. Our work provides a useful methodology for practically coping with decoherence with a limited number of qubits and paves the way for realizing noisy intermediate-scale quantum computing and quantum communication.
Abstract Quantum teleportation as the key strategy for quantum communication requires pure maximally shared entangled states among quantum nodes. In practice, quantum decoherence drastically degrades the shared entanglement during entanglement distribution, which is a serious challenge for the development of quantum networks. However, most of the decoherence control strategies proposed thus far are either resource-intensive or time-consuming. To overcome this obstacle, we enable noise-resistant teleportation through a noisy channel with a limited number of qubits and without applying time-consuming weak measurements. We apply a quantum gate control unit consisting of a controlled NOT gate and a rotation gate after the original teleportation protocol is accomplished. Furthermore, we demonstrate that a teleportation fidelity of unity is attainable when environment-assisted measurement is added to the proposed teleportation protocol via quantum gates. Moreover, we present an entanglement distribution process by employing the designed quantum gate control unit followed by the deterministic standard teleportation protocol to improve teleportation fidelity by establishing improved shared entanglement. Our performance analysis indicates that the proposed teleportation schemes offer a competitive fidelity and success probability compared with the conventional schemes and a recent weak measurement-based teleportation protocol.