Certified randomness amplification by dynamically probing remote random quantum states

TL;DR

This paper demonstrates a secure method for amplifying imperfect randomness into near-perfect randomness across a quantum network using a 98-qubit trapped-ion processor, avoiding the need for co-located Bell tests.

Contribution

It introduces a protocol for remote certified randomness amplification leveraging large entangled states and real-time quantum gate streaming, enhancing security against malicious devices.

Findings

Achieved fidelity of 0.586 on 64-qubit random circuits.

Successfully amplified low-entropy randomness into near-perfect randomness.

Maintained quantum coherence for approximately 0.9 seconds.

Abstract

Cryptography depends on truly unpredictable numbers, but physical sources emit biased or correlated bits. Quantum mechanics enables the amplification of imperfect randomness into nearly perfect randomness, but prior demonstrations have required physically co-located, loophole-free Bell tests, constraining the feasibility of remote operation. Here we realize certified randomness amplification across a network by dynamically probing large, entangled quantum states on Quantinuum's 98-qubit Helios trapped-ion quantum processor. Our protocol is secure even if the remote device acts maliciously or is compromised by an intercepting adversary, provided the samples are generated quickly enough to preclude classical simulation of the quantum circuits. We stream quantum gates in real time to the quantum processor, maintain quantum state coherence for $\approx 0.9$ seconds, and then reveal the measurement bases to the quantum processor only milliseconds before measurement. This limits the time for classical spoofing to 30 ms and constrains the location of hypothetical adversaries to a $4{,}500$ km radius. We achieve a fidelity of 0.586 on random circuits with 64 qubits and 276 two-qubit gates, enabling the amplification of realistic imperfect randomness with a low entropy rate into nearly perfect randomness.