GRENOBLE, France – Dec. 7, 2015 – CEA-Leti today announced preliminary steps for demonstrating a quantum bit, or qubit, the building block of quantum information, in a process utilizing a silicon-on-insulator (SOI) CMOS platform.
While the leading solid-state-based approach today for treating quantum information uses superconducting qubits, there are several potential alternatives. These include semiconductor spin qubits, historically demonstrated in III-V materials, but with limited “lifetime” due to coupling between the electron spin and the nuclear spins of the III-V elements.
Only in recent years has the prospect of using nuclear spin-free, isotopically purified silicon-28, the most-common isotope, made silicon an especially attractive candidate for hosting electron spin qubits with a long quantum coherence time. The main challenge now is defining an elementary cell compatible with circuit upscaling to hundreds of qubits and more.
Leti and its long-time research partner Inac, a fundamental research division of CEA, are investigating a silicon-on-insulator (SOI) technology for quantum computing with proven scalability, since it was originally developed for CMOS VLSI circuits. In this approach, quantum dots are created beneath the gates of n-type (respectively p-type) field effect transistors, which are designed to operate in the “few-electron” (respectively “few-hole”) regime at cryogenic temperatures (below 0.1 K).
Leti and Inac have developed a process for mastering control of the operation of both types of devices using Leti’s SOI nanowire FET technology. Their teams have demonstrated the co-integration and successful operation of quantum objects with conventional CMOS control electronics (standard ring oscillators) on 300mm SOI substrates.
“This technology has acquired a certain degree of robustness, and we aim at using it with very minor modifications to demonstrate qubits co-integrated with their control electronics,” said Louis Hutin, scientific staff. “This co-integration success represents a critical asset for the eventual design of a quantum computer.”
The teams also are exploring implementation and evaluation of different spin manipulation and read-out schemes. Radio frequency reflectometry has demonstrated the ability to access single charge events and even their associated spin orientation. Other research has studied the possibility of an electrically driven control of the spin orientation by high-frequency gate modulation of a few-hole silicon transistor. This electrical approach is considered to be a highly promising alternative to the more common magnetic-field manipulation, due in part to its faster and more localized action. Moreover, this scheme can be seamlessly integrated in CMOS technology.
Localizing an elementary charge, controlling its spin orientation and reading it out are prerequisites to demonstrating a qubit device, the elementary host of quantum information. Leti and Inac have demonstrated those steps without resorting to disruptive technologies, exotic materials or architectures, paving the way to fabricating quantum bits on an SOI CMOS platform.
An actual qubit demonstration could be on the near horizon. The immediate next steps would be demonstrating a few (n>2) coupled qubits, and developing a strategy for long-range coupling of the qubits.
It is anticipated that the built-in parallelism in the treatment of quantum information will open new perspectives for cryptography, database searching or simulation of quantum processes.
About Leti (France)
As one of three advanced-research institutes within the CEA Technological Research Division, CEA Tech-Leti serves as a bridge between basic research and production of micro- and nanotechnologies that improve the lives of people around the world. It is committed to creating innovation and transferring it to industry. Backed by its portfolio of 2,800 patents, Leti partners with large industrials, SMEs and startups to tailor advanced solutions that strengthen their competitive positions. It has launched 54 startups. Its 8,500m² of new-generation cleanroom space feature 200mm and 300mm wafer processing of micro and nano solutions for applications ranging from space to smart devices. With a staff of more than 1,800, Leti is based in Grenoble, France, and has offices in Silicon Valley, Calif., and Tokyo. Follow us at www.leti.fr and @CEA_Leti.
About Inac (France)
CEA-Inac counts 500 people in 6 laboratories, each a joint research unit with University Joseph Fourier, and some with CNRS and Grenoble Institute of Technology. Inac is a major player in basic research and its research focuses are on (i) nanoscience, namely photonics, spintronics, nanoelectronics, polymer science and nanochemistry; (ii) cryogenic technologies mainly for space and large instruments; (iii) health (DNA damages) & biosensors; and (iv) correlated electron systems (superconductivity). Inac develops strong activities in nano- and material characterization (synchrotron, neutrons, NMR and EPR, TEM, ions…) through internal or shared research centres and with Inac research groups located at ESRF and ILL. Inac manages a 700 m2 clean room for upstream research and fast devices prototyping. Inac has three major commitments: (i) creating frontier science results in basic research (350 publications per year); (ii) creating value by ensuring technologies transfers (through typ. 20 patents per year, start-ups and partnerships in applied research); and (iii) training of first class scientists through PhDs (110 ongoing) and postdocs (50 ongoing).
