Periodic Reporting for period 2 - IQubitNet (Integrated multi-qubit devices for scalable quantum networks)
Reporting period: 2021-10-07 to 2022-10-06
The rules of quantum mechanics enable fundamentally new applications that would be impossible in a world governed by classical physics: quantum computers hold the promise to solve classically intractable problems, quantum communication can achieve unconditionally secure communication, and quantum metrology enables measurements beyond the limits of classical laws. A long-sought goal for extending the reach of quantum technologies across the globe is to realize a quantum network for the distribution of entanglement between multiple distant parties. Groundbreaking demonstrations have been possible thanks to optically active solid-state spin systems, providing the possibility to interconnect long-lived quantum memories, in the form of electron and nuclear spins, via traveling single photons, which are ideal long-distance information carriers. The big challenge today concerns the scaling of proof-of-concept demonstrations into practical applications.
With the project “Integrated multi-qubit devices for scalable quantum networks” we aim at investigating the optical and spin properties of novel color centers in diamond, which could provide performances beyond what offered by established qubit systems, such as higher operating temperatures and faster optical communication rates. Furthermore, we will investigate the use of diamond photonic nanostructures and photonic integrated circuits. By taking advantage of the scalability of modern nanofabrication processes, it will be possible to integrate on a single device a large number of quantum memories, where they can be individually and precisely manipulated by integrated electronics and photonics circuits. The capabilities of these devices will then be tested by implementing quantum networking protocols. A successful project will make diamond-based quantum communication devices compatible with existing information and communication technologies, opening the way for their deployment in real-world applications.
With the project “Integrated multi-qubit devices for scalable quantum networks” we aim at investigating the optical and spin properties of novel color centers in diamond, which could provide performances beyond what offered by established qubit systems, such as higher operating temperatures and faster optical communication rates. Furthermore, we will investigate the use of diamond photonic nanostructures and photonic integrated circuits. By taking advantage of the scalability of modern nanofabrication processes, it will be possible to integrate on a single device a large number of quantum memories, where they can be individually and precisely manipulated by integrated electronics and photonics circuits. The capabilities of these devices will then be tested by implementing quantum networking protocols. A successful project will make diamond-based quantum communication devices compatible with existing information and communication technologies, opening the way for their deployment in real-world applications.
The work completed from the beginning of the project to the end of the outgoing phase has focused on two main objectives: investigating the properties of novel color centers and their performances as optically accessible qubits; testing of hybrid integrated devices embedding a large number of these color centers together with optical and electrical interfaces. The results achieved so far allowed to demonstrate the tin-vacancy (SnV) center in diamond as a promising spin qubit, providing an efficient optical interface together with long spin coherence times. Furthermore, such qubit has been integrated with both a commercial electronic control chip as well as with a custom integrated photonic chip, demonstrating its compatibility with the scalable fabrication techniques needed to realize large-scale qubit systems.
The results of this Action significantly advanced the knowledge on fabrication and control of qubits based on tin-vacancy centers in diamond. These centers now show important advantages over established ones, including optical interfaces more efficient than nitrogen-vacancy centers as well as spin coherence times longer that silicon-vacancy centers in the same conditions. Additionally, the integrated platforms investigated during this Actions enabled to demonstrate the controlled inclusion of diamond color centers on chip, with an increase in number by an order of magnitude compared to previous reports. In the remainder of the project, we expect to demonstrate the operation of such hybrid platform as a highly efficient quantum repeater node. These results will be key in scaling up quantum networking demonstrations based on diamond color centers.