Fig. 2: QNodeOS architecture.
From: An operating system for executing applications on quantum network nodes
a, QNodeOS consists of a classical network processing unit (CNPU) and a quantum network processing unit (QNPU) (classical system). QNodeOS controls a QDevice (quantum hardware and low-level classical control). b, Schematic of our implementation of QNodeOS on a two-node setup in which both QDevices control a single qubit in a diamond NV centre. The CNPU is implemented on a general-purpose PC and the QNPU on an embedded system, connected by means of Gigabit Ethernet (blue). The QNPU connects to its QDevice by means of a serial peripheral interface (SPI) (pink). The two QNPUs (brown) and the two CNPUs (green) connect to each other by means of Gigabit Ethernet. The setup is based on ref. 38 with two QDevices (including AWGs and microcontroller units (MCUs); QDevices communicating over a classical digital input/output (DIO) interface) and a heralding station composed of a balanced 50:50 beam splitter (whose output ports are connected to superconducting nanowire single-photon detectors (SNSPDs) through optical fibres (red)), a time tagger (TT) and a complex programmable logic device (CPLD) that heralds the entanglement generation between QDevices and sends a classical message to the MCU.
