Conditional quantum operation of two exchange-coupled single-donor spin qubits in a MOS-compatible silicon device

Mateusz T Ma̧Dzik,David N Jamieson,Andrew S Dzurak,Fay E Hudson,Andrea Morello,Arne Laucht,Brett C Johnson,Alexander M Jakob,Kohei M Itoh

doi:10.1038/s41467-020-20424-5

Abstract

Silicon nanoelectronic devices can host single-qubit quantum logic operations with fidelity better than 99.9%. For the spins of an electron bound to a single-donor atom, introduced in the silicon by ion implantation, the quantum information can be stored for nearly 1 second. However, manufacturing a scalable quantum processor with this method is considered challenging, because of the exponential sensitivity of the exchange interaction that mediates the coupling between the qubits. Here we demonstrate the conditional, coherent control of an electron spin qubit in an exchange-coupled pair of 31P donors implanted in silicon. The coupling strength, J = 32.06 ± 0.06 MHz, is measured spectroscopically with high precision. Since the coupling is weaker than the electron-nuclear hyperfine coupling A ≈ 90 MHz which detunes the two electrons, a native two-qubit controlled-rotation gate can be obtained via a simple electron spin resonance pulse. This scheme is insensitive to the precise value of J, which makes it suitable for the scale-up of donor-based quantum computers in silicon that exploit the metal-oxide-semiconductor fabrication protocols commonly used in the classical electronics industry.

Highlights

Silicon nanoelectronic devices can host single-qubit quantum logic operations with fidelity better than 99.9%
The donors are placed in a static magnetic field B0 (≈1.4 T in our experiment) and their spins are described by the electron (St, Sc, with basis states j"i; j#i) and nuclear (It, Ic, with basis states j*i; j+i) spin 1/2 vector Pauli operators; the subscripts “c” and “t”
We have presented the experimental observation of weak exchange coupling between the electron spins of a pair of 31P donors implanted in 28Si

Summary

Introduction

Silicon nanoelectronic devices can host single-qubit quantum logic operations with fidelity better than 99.9%. We demonstrate the conditional, coherent control of an electron spin qubit in an exchange-coupled pair of 31P donors implanted in silicon. Since the coupling is weaker than the electron-nuclear hyperfine coupling A ≈ 90 MHz which detunes the two electrons, a native two-qubit controlled-rotation gate can be obtained via a simple electron spin resonance pulse This scheme is insensitive to the precise value of J, which makes it suitable for the scale-up of donor-based quantum computers in silicon that exploit the metal-oxide-semiconductor fabrication protocols commonly used in the classical electronics industry. The weak interaction regime is crucial to ensure a mode of operation that is compatible with the inherent manufacturing tolerances of silicon MOS devices In their simplest form, two-qubit logic gates can be executed using three distinct strategies.

Methods

Results

Conclusion