Compact spin qubits using the common gate structure of fin field-effect transistors

Tetsufumi Tanamoto,Keiji Ono

doi:10.1063/5.0039521

Abstract

The sizes of commercial transistors are of nanometer order, and there have already been many proposals of spin qubits using conventional complementary metal–oxide–semiconductor transistors. However, most of the previously proposed spin qubits require many wires to control a small number of qubits. This causes a significant “jungle of wires” problem when the qubits are integrated into a chip. Herein, to reduce the complicated wiring, we theoretically consider spin qubits embedded into fin field-effect transistor (FinFET) devices such that the spin qubits share the common gate electrode of the FinFET. The interactions between qubits occur via the Ruderman–Kittel–Kasuya–Yosida interaction via the channel of the FinFET. The possibility of a quantum annealing machine is discussed in addition to the quantum computers of the current proposals.

Highlights

Scalability and affinity with conventional computers are the most important features of semiconductor spin qubits1 when building a quantum circuit
The qubits based on current complementary metal–oxide–semiconductor (CMOS) fieldeffect transistor structures6,7 have become more important in handling the trend of miniaturization of transistors
Most of the previous qubit structures require approximately ten electrodes to define, control, and read out a qubit. This is because the direct qubit–qubit interaction requires a small distance between the two qubits, and the measurement structures are separated from the qubit–qubit interaction parts

Summary

INTRODUCTION

Scalability and affinity with conventional computers are the most important features of semiconductor spin qubits when building a quantum circuit. The benefits of semiconductor qubits enable us to use the accumulated knowledge and technologies of the miniaturization of semiconductor devices, the gate lengths of which are already less than 20 nm in commercial use In this respect, the qubits based on current complementary metal–oxide–semiconductor (CMOS) fieldeffect transistor structures have become more important in handling the trend of miniaturization of transistors. The high cost can only be made affordable if a large number of chips are expected to be sold in a large market, such as smartphones, which would be far-future for quantum computers because they currently only work at very low temperatures From this perspective, qubit structures should be as similar to those of conventional transistors as possible. The present setup does not include the single-shot readout mechanism by using the fin channels as the couplers between the qubits as well as the measurement current lines, the number of wires is reduced, and we pave the way for solving the “jungle of wires” problem

Implementing qubits between the fin channels

Detailed analysis of the common-gate spin qubits

Measurement process

RKKY interaction and coherence time

THE VARIATION IN THE SIZE OF QDs

DISCUSSION