Due to its superior maturity in large-scale nanofabrication, silicon is the flagship material from both the microelectronics and integrated photonics industries. As a logical consequence, this semiconductor is one of the most desirable platforms to develop new technologies based on the control of physical systems obeying not to classical but to quantum mechanics laws. These systems, commonly called quantum bits or qubits, can be used as quantum information carriers. Up to recently, qubits in silicon detactable and controllable at individual scale were split into two types. On one hand, single electrons trapped in the silicon crystal using either metal electrodes or impurities can locally store quantum information for long time. However, they are lacking an optical interface required for long-distance communications. On the other hand, particles of light called photons, can be generated inside silicon with laser using optical non-linear processes. But unfortunately, they are not coupled to memory qubits to locally store information.
Lately, a new type of individual quantum systems has been detected in silicon: fluorescent point defects. These systems, also called color centers, can be excited by lasers and in response emit fluorescent light, like artificial atoms trapped in the silicon crystal. They can be detected at single-defect scale using advanced microscopy technics at cryogenic temperatures, typically bellow -240°C. These color centers have the benefit of emitting single photons in the telecom band, i.e. in the range of light that can propagate over the greatest distances in optical fibers used for the Internet. Furthermore, some fluorescent defects do possess an additional quantum degree of freedom associated with a non-zero spin state that can encode quantum information. As a consequence, optically-active spin defects could combine a spin memory qubit interfaced with telecom single photons.
The goal of the SILEQS project is to explore the quantum properties of these single color centers recently detected in silicon. A first objective relates to the control of their luminescence in order to have the defects generating photons one after the other with identical properties. A second one concerns the control of their spin states, down to the single-defect level. Like other quantum systems, particular attention will be given to the impact of their environment on the defects' quantum properties.
