Experimental demonstration of secure quantum remote sensing. (arXiv:1907.06480v1 [quant-ph])

Quantum metrology aims to enhance the precision of various measurement tasks
by taking advantages of quantum properties. In many scenarios, precision is not
the sole target; the acquired information must be protected once it is
generated in the sensing process. Considering a remote sensing scenario where a
local site performs cooperative sensing with a remote site to collect private
information at the remote site, the loss of sensing data inevitably causes
private information to be revealed. Quantum key distribution is known to be a
reliable solution for secure data transmission, however, it fails if an
eavesdropper accesses the sensing data generated at a remote site. In this
study, we demonstrate that by sharing entanglement between local and remote
sites, secure quantum remote sensing can be realized, and the secure level is
characterized by asymmetric Fisher information gain. Concretely, only the local
site can acquire the estimated parameter accurately with Fisher information
approaching 1. In contrast, the accessible Fisher information for an
eavesdropper is nearly zero even if he/she obtains the raw sensing data at the
remote site. This achievement is primarily due to the nonlocal calibration and
steering of the probe state at the remote site. Our results explore one
significant advantage of quantumness'' and extend the notion of quantum
metrology to the security realm.