Improved Interface for a Quantum InternetA quantum network requires efficient interfaces over which information can be transferred from matter to light and back.
Building a Quantum Internet requires the development of innovative quantum-enabling networking architectures that integrate advanced communication systems with long-distance quantum communication hardware. Here, we present the implementation of a quantum-enabled internet prototype using a novel physics-centric stack-based quantum network paradigm to govern the dynamics of multiple light-matter Hamiltonians across distant nodes. We demonstrate this concept using a deployed large-scale intercity quantum network connecting laboratories at Stony Brook University and the Brookhaven National Laboratory. This network facilitates a fundamental long-distance quantum network service -that of high-visibility Hong-Ou-Mandel interference of telecom quantum states generated in two independent, telecom-compatible quantum light-matter interfaces separated by a distance of 158 km.
A coherent interface between optical photons and long-lived matter qubits can form the basis for a broad range of quantum technologies. I will describe the realization of such an interface using inversion-symmetric color-centers integrated into diamond nanophotonic devices at millikelvin temperatures. The resulting high-cooperativity spin-photon interface can be fabricated en-masse and exhibits a unique combination of long coherence times, high-fidelity control, strong light-matter interactions, and efficient photon out-coupling, establishing it as a leading platform for the construction of a large-scale quantum internet.
In quantum information technology, it is necessary to develop a light-matter quantum interface that transfers and stores quantum information. As a bandwidth of quantum entangled photon pairs used for quantum information increases, a quantum interface with broad bandwidth will be required. The combination of quantum dot (QD) ensemble and photon echo (PE) method is one of promising methods for broadband quantum interface. Since the bandwidth of the quantum interface using this method is limited only by the inhomogeneous width of the QDs, it is possible to implement a quantum interface with the bandwidth of 10 THz at telecommunication wavelength. However, in the PE method, the spatial inhomogeneousity of the laser intensity and the inhomogeneousity of the resonance frequency of the QDs result in the uniform quantum control of excitons in QDs. As a result, the regeneration efficiency of the PE light is significantly deteriorated. To solve this problem, it is effective to introduce a quantum control method using chirped pulses (Adaptive Rapid Passages; ARPs) which is robust to inhomogeneousities. In this study, we demonstrate that the regeneration efficiency of PE in inhomogeneous QDs can be improved by ARPs using femtosecond pulses. By performing numerical simulation and optical experiments, it was found that the regeneration efficiency improves as the chirp amount and the pulse area increase, and saturates at a certain condition.