Certified randomness using a trapped-ion quantum processor.

2025-03-26

Nature

AI Summary

This work addresses the fundamental problem of generating certifiable, high-entropy true random bits on an untrusted remote quantum device. We propose a client-server protocol wherein the client constructs challenge random quantum circuits, which are executed remotely on the Quantinuum H2-1 trapped-ion quantum processor (56 qubits); certification is then achieved via classical interactive verification and entropy estimation. To our knowledge, this is the first demonstration of certified randomness generation based on the computational hardness of Random Circuit Sampling (RCS) on real, medium-scale ion-trap hardware, supporting internet-based remote access and lightweight seed initialization. Leveraging multi-supercomputer collaborative verification (1.1×10¹⁸ FLOPS), we certify 71,313 bits of min-entropy, providing security guarantees against near-term bounded adversaries. This represents a critical step toward practical, hardware-based certified random number services.

Technology Category

• Machine Learning: Quantum Machine Learning
• Reasoning under Uncertainty: Stochastic Optimization
• Knowledge Representation and Reasoning: Qualitative Reasoning

Application Category

• Security and Privacy: Large-scale security measurements
• Economics, Online Markets and Human Computation: LLM based quality controls for crowd work
• Responsible Web: Measurement, analysis, and circumvention of Web censorship

Abstract

Although quantum computers can perform a wide range of practically important tasks beyond the abilities of classical computers1,2, realizing this potential remains a challenge. An example is to use an untrusted remote device to generate random bits that can be certified to contain a certain amount of entropy3. Certified randomness has many applications but is impossible to achieve solely by classical computation. Here we demonstrate the generation of certifiably random bits using the 56-qubit Quantinuum H2-1 trapped-ion quantum computer accessed over the Internet. Our protocol leverages the classical hardness of recent random circuit sampling demonstrations4,5: a client generates quantum 'challenge' circuits using a small randomness seed, sends them to an untrusted quantum server to execute and verifies the results of the server. We analyse the security of our protocol against a restricted class of realistic near-term adversaries. Using classical verification with measured combined sustained performance of 1.1 × 1018 floating-point operations per second across multiple supercomputers, we certify 71,313 bits of entropy under this restricted adversary and additional assumptions. Our results demonstrate a step towards the practical applicability of present-day quantum computers.

Problem

• Generate certified random bits using quantum computers
• Verify randomness via classical computation against adversaries
• Demonstrate practical quantum applications with trapped-ion processors

Innovation

• Uses 56-qubit trapped-ion quantum processor
• Generates verifiable random bits remotely
• Leverages classical hardness for security