Concepedia

Operating Quantum States in Single Magnetic Molecules: Implementation of Grover’s Quantum Algorithm

Clément Godfrin, Abdelkarim Ferhat, R. Ballou, Svetlana Klyatskaya, Mario Ruben, Wolfgang Wernsdorfer, Franck Balestro

Physical Review Letters · 2017 · 364 citations · 34 references

Open access

TL;DR

Quantum algorithms exploit quantum superposition to outperform classical computation in cryptography, searching, optimization, simulation, and solving large linear systems. The study implements Grover’s algorithm to locate an element in an unsorted list using a single nuclear 3/2 spin in a Tb ion within a single‑molecule magnet transistor. Coherent manipulation of this multilevel qudit is achieved solely by electric fields, constructing a quantum database via a multilevel Hadamard gate and applying the Grover sequence to select each state. The method is universal and can be applied to any multilevel quantum system with non‑equally spaced energy levels, enabling novel quantum search algorithms.

Abstract

Quantum algorithms use the principles of quantum mechanics, such as, for example, quantum superposition, in order to solve particular problems outperforming standard computation. They are developed for cryptography, searching, optimization, simulation, and solving large systems of linear equations. Here, we implement Grover's quantum algorithm, proposed to find an element in an unsorted list, using a single nuclear 3/2 spin carried by a Tb ion sitting in a single molecular magnet transistor. The coherent manipulation of this multilevel quantum system (qudit) is achieved by means of electric fields only. Grover's search algorithm is implemented by constructing a quantum database via a multilevel Hadamard gate. The Grover sequence then allows us to select each state. The presented method is of universal character and can be implemented in any multilevel quantum system with nonequal spaced energy levels, opening the way to novel quantum search algorithms.