High-temperature operation of a silicon qubit

Keiji Ono,Takahiro Mori,Satoshi Moriyama

doi:10.1038/s41598-018-36476-z

Abstract

This study alleviates the low operating temperature constraint of Si qubits. A qubit is a key element for quantum sensors, memories, and computers. Electron spin in Si is a promising qubit, as it allows both long coherence times and potential compatibility with current silicon technology. Si qubits have been implemented using gate-defined quantum dots or shallow impurities. However, operation of Si qubits has been restricted to milli-Kelvin temperatures, thus limiting the application of the quantum technology. In this study, we addressed a single deep impurity, having strong electron confinement of up to 0.3 eV, using single-electron tunnelling transport. We also achieved qubit operation at 5–10 K through a spin-blockade effect based on the tunnelling transport via two impurities. The deep impurity was implemented by tunnel field-effect transistors (TFETs) instead of conventional FETs. With further improvement in fabrication and controllability, this work presents the possibility of operating silicon spin qubits at elevated temperatures.

Highlights

This study alleviates the low operating temperature constraint of Si qubits
We propose and demonstrate a novel Si qubit by taking advantage of an individual deep impurity embedded in Si tunnel field-effect transistors (TFETs) for electrically addressable spin qubits, to realise higher-temperature operation
Some reports have suggested the feasibility of room-temperature operation: the ensemble characteristics of spins bound to deep impurities have been investigated using electrically detected magnetic resonance[11], and the electron spins of dangling bond defects and neighbouring 29Si nuclear spins have been detected in MOS field-effect transistors (MOSFETs) at room temperature[12]

Summary

Introduction

This study alleviates the low operating temperature constraint of Si qubits. A qubit is a key element for quantum sensors, memories, and computers. We achieved qubit operation at 5–10 K through a spin-blockade effect based on the tunnelling transport via two impurities. The deep impurity was implemented by tunnel field-effect transistors (TFETs) instead of conventional FETs. With further improvement in fabrication and controllability, this work presents the possibility of operating silicon spin qubits at elevated temperatures. We propose and demonstrate a novel Si qubit by taking advantage of an individual deep impurity embedded in Si tunnel field-effect transistors (TFETs) for electrically addressable spin qubits, to realise higher-temperature operation. Quantum-dot-like transport has been achieved using shallow impurities in the channels of miniaturised MOSFETs15–18 This transport involved two-step tunnelling from a source to a drain by utilising the shallow impurity level. To realise tunnel coupling with deep impurities, it is necessary to utilise extremely short-channel MOSFETs, which cannot be achieved using the www.nature.com/scientificreports/

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