Experimental Quantum Randomness Processing

TL;DR

This paper demonstrates a quantum protocol leveraging single-qubit coherence, implemented with superconducting qubits, that outperforms classical methods in randomness processing without requiring entanglement.

Contribution

It introduces a novel quantum protocol based solely on coherence, experimentally validated using superconducting qubits, showing advantages over classical approaches.

Findings

Quantum coherence enables randomness processing beyond classical limits.

Superconducting qubits can implement the protocol with high fidelity.

Quantum advantage achieved without multipartite entanglement.

Abstract

Coherently manipulating multipartite quantum correlations leads to remarkable advantages in quantum information processing. A fundamental question is whether such quantum advantages persist only by exploiting multipartite correlations, such as entanglement. Recently, Dale, Jennings, and Rudolph negated the question by showing that a randomness processing, quantum Bernoulli factory, using quantum coherence, is strictly more powerful than the one with classical mechanics. In this Letter, focusing on the same scenario, we propose a theoretical protocol that is classically impossible but can be implemented solely using quantum coherence without entanglement. We demonstrate the protocol by exploiting the high-fidelity quantum state preparation and measurement with a superconducting qubit in the circuit quantum electrodynamics architecture and a nearly quantum-limited parametric amplifier. Our experiment shows the advantage of using quantum coherence of a single qubit for information processing even when multipartite correlation is not present.