Quantum Location Verification in Noisy Channels

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.