Secure quantum ranging
ORAL
Abstract
Determining and verifying an object’s position is a fundamental task in sensing and navigation. We present a secure quantum ranging protocol that combines quantum-enhanced ranging with quantum position verification, enabling both high-precision distance estimation and the detection of spoofing attacks. Our scheme employs frequency-entangled photonic states distributed from two spatially separated verifiers to a prover, who performs a pre-negotiated operation and returns the states to the verifiers without delay. The protocol achieves Heisenberg-limited precision in position estimation while remaining secure against dishonest adversaries attempting to impersonate a prover at a false location.
In the protocol, an honest prover is required only to perform a simple linear-optical operation. In contrast, two colluding cheaters, positioned on opposite sides of a false prover location, are allowed arbitrary linear-optical processing, a single ancillary mode, and ideal quantum memories, but are assumed to have no pre-shared entanglement. We show that security critically relies on randomization over the input states and on the appropriate choice of operations performed by the prover, and we derive explicit bounds on the probability of detecting cheating. Independently, the achievable ranging precision is quantified using the Fisher information, which depends on the degree of frequency-domain entanglement in the employed states, with higher entanglement leading to enhanced ranging precision. Our protocol can be experimentally implemented using frequency-entangled biphoton states generated via spontaneous parametric down-conversion.
Our results establish a connection between quantum metrology and cryptographic security, showing how quantum properties simultaneously improve ranging precision and security against spoofing. Besides this connection, quantum position verification often assumes infinite precision and focuses primarily on computational aspects; our work provides a quantitative framework for finite-precision effects.
In the protocol, an honest prover is required only to perform a simple linear-optical operation. In contrast, two colluding cheaters, positioned on opposite sides of a false prover location, are allowed arbitrary linear-optical processing, a single ancillary mode, and ideal quantum memories, but are assumed to have no pre-shared entanglement. We show that security critically relies on randomization over the input states and on the appropriate choice of operations performed by the prover, and we derive explicit bounds on the probability of detecting cheating. Independently, the achievable ranging precision is quantified using the Fisher information, which depends on the degree of frequency-domain entanglement in the employed states, with higher entanglement leading to enhanced ranging precision. Our protocol can be experimentally implemented using frequency-entangled biphoton states generated via spontaneous parametric down-conversion.
Our results establish a connection between quantum metrology and cryptographic security, showing how quantum properties simultaneously improve ranging precision and security against spoofing. Besides this connection, quantum position verification often assumes infinite precision and focuses primarily on computational aspects; our work provides a quantitative framework for finite-precision effects.
*Supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), the NSERC–UKRI Alliance (ALLRP 597823-24), the Canada First Research Excellence Fund, and the NSERC–NSF Alliance (ALLRP-586858-2023).
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Publication: Phys. Rev. Lett. 135, 260802 (2025)
Presenters
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Yunkai Wang
- University of Waterloo