CE47 - Technologies quantiques

Integrated quantum optics using Site-controlled Quantum Dots and molecules – I-SQUAD

Submission summary

Entanglement between stationary quantum memories and photonic qubits is crucial for future quantum communication networks. Motivated by this potential application, a promising research direction investigating quantum coherent optical manipulation and measurement of individual isolated spin qubits has emerged.
The discrete density of states of semiconductor quantum dots and their easy integration into conventional semiconductor device structures make them ideal for such applications. Coupled quantum dots, where carriers can tunnel coherently between the dots, have even greater potential: as storage units for spin qubits with long coherence times or as quantum gates needed for quantum computation. Self-assembled quantum dots have already demonstrated to be very efficient quantum light sources but their random position presents an obstacle for their integration in quantum photonic circuits and networks.
We propose to develop a new fabrication process for an integrated quantum optics platform based on site-controlled dots integrated in photonic crystal cavities linked by planar one-dimensional waveguide structures and demonstrate on-chip entanglement from remote spin qubits using this platform.
- The first objective of the project is to establish a growth strategy for strained quantum dots molecules (QDM) with unprecedented precision over the dots' position, energy and tunnel coupling rate. This strategy is based on the use of nanohole-patterned substrates to exert control over the migration of adatoms on the growing surface, leading to controllable nanoscale variations in thickness and composition during growth. Ex-situ nanohole patterned substrates will be used to demonstrate a robust, fully scalable process to create arrays of QDM. This a fundamental step in the creation of a quantum network of optically connected coupled quantum dot quantum gates.
- Photon extraction remains the principal challenge in realizing an efficient spin-photon interface. Embedding the emitters in photonic structures to take advantage of cavity quantum electrodynamics effects in a deterministic way will be our second objective. The QDM energy levels will be controlled with locally applied electric fields, perfectly matched to the optical mode of a photonic crystal (PhC) cavity coupled with highly efficient light injector/extractors.
- The goal of the I-SQUAD project is to establish the experimental conditions necessary for the realization of spin-spin entanglement on chip. Two demonstrators will be realized: a full spin control gate (initialization, coherent control and readout) with a QDM hole spin embedded in a PhC cavity and a demonstration of spin-photon entanglement. Together with on-chip two-photon interference from two different QDMs, these demonstrators will represent building blocks for future local quantum networks based on interconnected small-scale quantum information processors.

Project coordinator

Institut des nanosciences de Paris (Laboratoire public)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


Institut des nanosciences de Paris
Centre de Nanosciences et de Nanotechnologies
Institut des nanosciences de Paris
Laboratoire Photonique, Numérique, Nanosciences

Help of the ANR 578,347 euros
Beginning and duration of the scientific project: December 2018 - 48 Months

Useful links