Experimental Implementation of Efficient Quantum Pseudorandomness on a 12-spin System

TL;DR

This paper demonstrates an efficient experimental method to generate quantum pseudorandomness on a 12-spin system using a design Hamiltonian approach, advancing practical quantum information processing.

Contribution

It implements a novel, more efficient protocol for creating quantum pseudorandomness in a physical system, validated through experimental measurements.

Findings

Successful creation of quantum pseudorandomness in a 12-spin system

Use of design Hamiltonian approach for efficiency

Measurement of quantum coherence spreading confirms pseudorandomness

Abstract

Quantum pseudorandomness, also known as unitary designs, comprise a powerful resource for quantum computation and quantum engineering. While it is known in theory that pseudorandom unitary operators can be constructed efficiently, realizing these objects in realistic physical systems can be a challenging task. In this work, we study quantum pseudorandomness generation on a 12-spin nuclear magnetic resonance system. The experimental process is based on the recently proposed design Hamiltonian approach, which has the merit of being significantly more efficient than previous protocols. By applying random refocusing sequences to the experimental system we create a design Hamiltonian the dynamics of which quickly forms unitary designs. We then use multiple-quantum techniques to measure spreading of quantum coherences over system's degrees of freedom, and so to probe the growth of quantum pseudorandomness. The measured multiple-quantum coherence spectra indicate that substantial quantum pseudorandomness have been achieved.