A Single-Electron Injection Device for CMOS Charge Qubits Implemented in 22-nm FD-SOI

Abstract

This brief presents a single-electron injection device for position-based charge qubit structures implemented in 22 nm FD-SOI CMOS. Quantum dots are implemented in local well areas separated by tunnel barriers controlled by gate terminals overlapping with a thin 5 nm undoped silicon film. Interface of the quantum structure with classical electronic circuitry is provided with single-electron transistors that feature doped wells on the classic side. A small 0.7×0.4 µm 2 elementary quantum core is co-located with control circuitry inside the quantum operation cell which is operating at 3.5 K and a 2 GHz clock frequency. With this apparatus, we demonstrate a single electron injection into a quantum dot.Index Terms-Single-electron injection device (SEID), cryogenic circuits, position-based charge qubit, quantum computer, quantum point contact (QPC), quantum operation cell, quantum dot (QD), fully depleted silicon-on-insulator (FD-SOI).

A Fully Integrated DAC for CMOS Position-Based Charge Qubits with Single-Electron Detector Loopback Testing

“…Fig. 1 presents an overview of the CMOS position-based charge qubit structure containing an array of QDs [9], [11], [12], with schematics of nearby interfacing circuitry: reset, control, singleelectron injector, and detector. It is part of a quantum processor implemented in 22-nm FDSOI CMOS and operating at cryogenic temperature of 3.4 K, whose earlier version was presented in [10].…”

“…Our proposed quantum processor unit (QPU) uses on-chip interface circuitry to electrostatically set the quantum states of position-based charge qubits in accordance with a given quantum algorithm [9]- [12]. These proposed quantum states are controlled by adjusting potential barriers between quantum dots (QDs) to establish, via tunneling and entanglement, the intended functions of quantum gates.…”

“…This demands high-speed voltage pulses with fine amplitude and width resolution, complexity of which grows with the QD array (QDA) structure size. In contrast with the spin-based qubit interfaces that require wide bandwidth circuitry operating at microwaves [4], the charge-based qubits can be electrostatically interfaced with baseband pulses [10], [12]. Furthermore, although the charge qubits are known to suffer from the relatively short decoherence time (50 ns to 1 µs), the ultra-high transition frequency f T in advanced CMOS can help to fit over a thousand quantum gate operations within the useful decoherence duration [9].…”

“…As a solution, we exploit the nearby single-electron detector in a test loopback configuration. A concurrent letter [12] covers some theoretical aspects of the implemented QDA structure and primarily focuses on injecting single electrons into the QDs. This CDAC is one of the key blocks used for that purpose.…”

Towards the Co-Simulation of Charge Qubits: A Methodology Grounding on an Equivalent Circuit Representation

“…In this paper, we have chosen an example of a quantum dot array recently implemented in a CMOS technology together with their interface electronics [22], [35]. We propose and discuss in detail a modeling methodology particularly focused on the side of the problem that may be appealing to readers with background in circuit design.…”