Progress achieved in the field of microelectronics during the past half-century has essentially relied on silicon (Si) technology development. Following several decades of research and the introduction of novel materials (e.g. high-? dielectrics and metal gate) in order to meet requirements in terms of performance and power consumption, CMOS technological platforms remain Si-based to this day.

Over the course of the last few years, it was shown that silicon and silicon-germanium alloys (SiGe) could be suitable material candidates for studying new generations of quantum electronics devices. By analogy with classical electronics, the quantum bit (qubit) is the fundamental building block for quantum computing1. As opposed to conventional computing for which a bit can only carry one among two possible logic states (0 or 1), the qubit is a superposition of the |0> and |1> eigenstates, thus considerably increasing the information processing capability. Various physical systems are currently being studied in order to create qubits. A promising approach, based on silicon technology, consists in encoding quantum information within the spin state of strongly confined electrons (an electron under a magnetic field naturally forms a two-state quantum system derived from the two opposite spin directions, parallel and anti-parallel to the field). The spin presents the advantage of a relatively low coupling to electromagnetic noise, hence enabling long-lived quantum coherence. Achieving control over coupling between the qubits themselves remains one of the major challenges in fabricating a quantum computer. To this end, the versatility in circuit design and fabrication inherited from the microelectronics industry is a major asset.

The proposed PhD project will firstly consist in carrying out a state-of-the-art review of design and integration schemes currently implemented for fabricating spin qubits, in order to reach a thorough understanding of their operation, advantages and limitations. Building on the basis of a solid grasp of the physical mechanisms at stake in such structures, novel integration schemes aiming at improving their characteristics will be investigated. To this purpose, the student will fully benefit from the silicon technological platform at CEA-LETI, and from the maturity of technological processes used nowadays in microelectronics. Advanced lithography techniques and reticles used for the fabrication of “SETs” (Single Electron Transistors) and “electron pumps” will be leveraged for developing these novel devices.

This position is open until it is filled.

Department: Département Composants Silicium (LETI)
Laboratory: Laboratoire Composants Logiques
Start Date: 01-09-2015
ECA Code: SL-DRT-15-0096
Contact: sylvain.barraud<στο>cea.fr