Embedded quantum-error correction and controlled-phase gate for molecular spin qubits

A. Chiesa,S. Wimberger,S. Carretta,E. Macaluso,F. Petiziol,P. Santini

doi:10.1063/9.0000166

Abstract

A scalable architecture for quantum computing requires logical units supporting quantum-error correction. In this respect, magnetic molecules are particularly promising, since they allow one to define logical qubits with embedded quantum-error correction by exploiting multiple energy levels of a single molecule. The single-object nature of this encoding is expected to facilitate the implementation of error correction procedures and logical operations. In this work, we make progress in this direction by showing how two-qubit gates between error-protected units can be realised, by means of easily implementable sequences of electro-magnetic pulses.

Highlights

Recent progresses in the quantum computing technology have led to the realization of noisy intermediate-scale quantum computers (NISQ1) with remarkable performance.2–8 NISQ devices are only a halfway step toward the implementation of a scalable, general purpose quantum computer
We have shown that magnetic molecules are promising logical units for a forthcoming, scalable quantum computing architecture
They can embed quantum error correction at the single molecule level, avoiding the large increase of hardware resources typically required by block-encoding quantum-error correction (QEC) schemes

Summary

INTRODUCTION

Recent progresses in the quantum computing technology have led to the realization of noisy intermediate-scale quantum computers (NISQ1) with remarkable performance. NISQ devices are only a halfway step toward the implementation of a scalable, general purpose quantum computer. It was recently shown that magnetic molecules provide the ideal playground for such an architecture, thanks to their rich and chemically tunable spectrum, characterized by many (more than the two needed for un unprotected qubit) available and individually addressable low-energy levels These systems have already demonstrated remarkable coherence times, 12–16 along with the possibility of being arranged in supra-molecular structures tailored for specific or general purpose quantum computing applications.. On-going pure dephasing, that this procedure implements a switchable two-qubit gate between the logical qubits, with very small overhead of resources and manipulation requirements compared to its uncorrected version These results suggest the proposed system as a promising building-block for a future scalable quantum-computing architecture.

Spin-binomial code words for pure dephasing

Physical implementation and general pulse sequence

TWO-QUBIT GATES

CONCLUSIONS AND OUTLOOK