QUANT-NET is a three-node quantum network research testbed funded by the U.S. Department of Energy (DOE). The goal is to establish this network between two sites, Lawrence Berkeley National Lab (LBNL) and University of California, Berkeley, connected with an entanglement swapping substrate over optical fiber and managed by a quantum network protocol stack. On top of this entanglement swapping substrate the research team will implement the most basic building blocks of distributed quantum computing and quantum repeater by teleporting a controlled-NOT gate between two far trapped-ion quantum computation nodes. This paper presents QUANT-NET, its design, key technologies, and progress.
QUANT-NET is a three-node quantum network research testbed funded by the U.S. Department of Energy (DOE). The goal is to establish this network between two sites, Lawrence Berkeley National Lab (LBNL) and University of California, Berkeley, connected with an entanglement swapping substrate over optical fiber and managed by a quantum network protocol stack. On top of this entanglement swapping substrate the research team will implement the most basic building blocks of distributed quantum computing and quantum repeater by teleporting a controlled-NOT gate between two far trapped-ion quantum computation nodes. This paper presents QUANT-NET, its design, key technologies, and progress.
The U.S. Department of Energy (DOE) is currently supporting Berkeley Lab (LBNL), UC Berkeley (UCB), Caltech, and the University of Innsbruck in constructing a testbed for quantum networking technologies (QUANT-NET). The goal is to establish this network between two sites, LBNL and UCB, connected with an entanglement swapping substrate over ~5 km optical fiber and managed by a quantum network protocol stack. On top of this entanglement swapping substrate the research team will implement the most basic building blocks of distributed quantum computing and quantum repeaters by teleporting a controlled-NOT gate between two far trapped-ion quantum computation nodes. This paper presents QUANT-NET, its design, key technologies, and preliminary results. The preliminary results are focused on the QUANT-NET testbed infrastructure control, measurement, and characterization, which includes the implementation of a Hong-Ou-Mandel (HOM) interferometer across the fiber links, and the development and deployment of link polarization drift control in the testbed. These implementations are critical to our next stage research activities.
Enabling secure communication, unparalleled computing capabilities, and fundamental nonlocality physics exploration, the development of quantum repeaters is the key quantum information processing technology advance needed for implementing real world quantum networks beyond the laboratory environment. Currently, components exist for intra-laboratory quantum networks but no system exists for connecting distant ( 1 km ) quantum memories in the real world. We present a physics analysis of quantum repeater network designs for intracity optical fiber connections between nodes based on atomic memories and linear optics. Long distances will necessitate the use of (1) two-photon Hong-Ou-Mandel style interference between atomic ensembles for entanglement swapping, and (2) photonic qubit wavelength conversion between atomic emissions and photons at telecommunication wavelengths in fiber. We report on our experimental progress towards implementing A Quantum Network with Atoms and Photons (QNET-AP), a quantum repeater network test-bed, between the US Army Research Laboratory (ARL) and the Joint Quantum Institute (JQI) of the National Institute of Standards and Technology (NIST) and the University of Maryland (UMD).
Quantum network control is a major research area of the QUANT-NET project. We strive to build a quantum network control plane to orchestrate and manage all the physicallayer technologies, and to explore what a quantum network control plane should look like in the future, so as to automate high-rate and high-fidelity entanglement generation, distribution, and storage in an efficient, reliable, and cost-effective way. To these ends, we have designed a two-level control framework for quantum networks. Within such a framework, a two-level scheduler has been implemented to support synchronous time slot scheduling, network-wide non-real-time control, and nodewide real-time control. This two-level control framework and the scheduler are being deployed and evaluated in the QUANTNET testbed. Enabled by this two-level control framework and the scheduler, several basic quantum network operations have been automated in the testbed, which include automated quantum node calibration and on-demand single photon generation. In this paper, we present this two-level control framework, the scheduler, and the automated quantum network operations that have been enabled in the QUANT-NET testbed.
The Internet has revolutionized the way we live. It has enabled applications far beyond what it was originally built for, and it will continue to exceed our expectations for the future. Quantum computers, and the network that will connect them—the Quantum Internet— are likely going to follow the same path. Differently from normal computers, quantum computers can share a property called entanglement, which allows the qubits (quantum bits) to be connected at a much more fundamental level. This property enables a range of new applications that span secure communication to enhanced metrology. Over the past fifteen years, significant progress has been made in connecting rudimentary quantum network nodes via long-distance entanglement. Several quantum platforms have demonstrated entanglement generation between two physically separated qubits. In this thesis we take a significant step forward, both in terms of experimental complexity achieved, and in the abstraction of said complexity for future developments. Moving past two-node experiments required a fundamental redesign of our experimental apparatus, as well as developing the capabilities to control simultaneously the additional node. The first result of this thesis is building a three-node entanglement-based quantum network. We demonstrated distribution of Greenberger-Horne-Zeilinger states over the network, as well as a building block for larger networks: entanglement swapping. Differently from previous multi-node demonstrations, which relied on post-selection, our network is able to perform the entanglement distribution in a heralded fashion: a signal will notify the users that the protocol was successful, and that the state is ready to be used. The second result builds on the first, by adding control over a fifth qubit, improving the quality of the entanglement, and introducing a novel repetitive readout technique, to achieve quantum teleportation of a qubit from the third node to the first—nodes that do not share a direct entanglement channel. The third and final result is the demonstration of entanglement delivery using a quantum network stack. The Internet is built using a plethora of physical platforms: optical fibers, Ethernet cables, Wi-Fi, satellite signals etc. To abstract their functionality, and make applications work regardless of the underlying platform, a layered approach was developed in the 1970s (the Internet protocol). Taking inspiration from classical network stacks, we demonstrate the first two layers of a quantum network stack, the physical layer (where the qubits, lasers and signal generators live), and the link layer, which abstracts the concepts of qubit and entanglement generation such that they can be used by applications at the higher-layers, hiding the complexity of the quantum platform being used.
The realization of quantum networks requires the development of devices and methods unprecedented in conventional networks, and yet they critically depend on the latter for implementing foundational blocks and essential operations. We describe a testbed to support the development and testing of their functionality and performance by providing quantum and conventional data planes and devices, together with a secure conventional control plane. It incorporates a variety of entangled photon sources, qubit technologies, detector technologies, photonic components, and supporting conventional switches and workstations. It implements a novel fiber telescoping scheme that provides suites of connections using fiber spools and inground-aerial fiber loops. We briefly summarize a variety of experiments conducted over this testbed including: (i) flex-grid quantum connection experiments, (ii) quantum state and channel tomography, (iii) utilization of quantum key distribution keys to secure conventional encryption and firewall devices, (iv) comparative study of analytical capacity estimates and entanglement throughput, (v) deployed squeezing coexisting with conventional communications, and (iv) measurement of polarization time variation.
We present the Quantum Communication Testbed NL, a four-node quantum key distribution network deployed in and around Eindhoven, The Netherlands. The main goal of the testbed is to provide an environment for testing quantum safe communications and demonstrating use cases and network applications. We describe the infrastructure stack, including the heterogeneous quantum key distribution equipment, our custom key management system using trusted relay nodes, and network encryptors. We also present monitoring and alerting solutions that integrate classical and quantum infrastructure, along with performance data that demonstrate how the testbed operates under near real-world conditions.