While few details accompanied last weeks official announcement of U.S. plans for a nation-wide quantum internet, many of the priorities and milestones had been worked out during a February workshop and are now available in subsequent reports. The Department of Energy is leading the effort which is part of the U.S. Quantum Initiative passed in 2019.

The race to harness quantum information science whether through computing, communications, or sensing has become a global competition. In many ways quantum communications is the furthest along in development and its promise of near absolute security is extremely alluring. DOEs 17 National Laboratories are intended to serve as the backbone of the U.S. quantum internet effort.

As noted in the official announcement, Crucial steps toward building such an internet are already underway in the Chicago region, which has become one of the leading global hubs for quantum research. In February of this year, scientists from DOEs Argonne National Laboratory in Lemont, Illinois, and the University of Chicagoentangled photons across a 52-milequantumloop in the Chicago suburbs, successfully establishing one of the longest land-based quantum networks in the nation. That network will soon be connected to DOEs Fermilab in Batavia, Illinois, establishing a three-node, 80-mile testbed.

Turning early prototypes into a scaled-up nationwide effort involves tackling many technical challenges. One thorny problem, for example, is development of robust repeater technology, which among other things requires reliable quantum memory technology and prevention of signal loss. Interestingly, satellites may play a role as a bridge according to the report:

A quantum Internet will not exist in isolation apart from the current classical digital networks. Quantum information largely is encoded in photons and transmitted over optical fiber infrastructure that is used widely by todays classical networks. Thus, at a fundamental level, both are supported by optical fiber that implements lightwave channels. Unlike digital information encoded and transmitted over current fiber networks, quantum information cannot be amplified with traditional mechanisms as the states will be modified if measured.

While quantum networks are expected to use the optical fiber infrastructure, it could be that special fibers may enable broader deployment of this technology. At least in the near term, satellite-based entanglement bridges could be used to directly connect transcontinental and transatlantic Q-LANs. Preliminary estimates indicate that entangled pairs could be shared at rates exceeding 106 in a single pass of a Medium Earth Orbit (MEO) satellite. Such a capability may be a crucial intermediate step, while efficient robust repeaters are developed (as some estimates predict more than 100 repeaters would be needed to establish a transatlantic link).

The report from the workshop spells out four priorities along with five milestones. (The event was chaired by Kerstin Kleese van Dam, Brookhaven National Laboratory; Inder Monga, Energy Sciences Network; Nicholas Peters, Oak Ridge National Laboratory; and Thomas Schenkel, Lawrence Berkeley National Laboratory).

Here are the four priorities identified in the report:

Some of the test cases being discussed are fascinating such as one across Long Island, NY:

For example, there would be considerable value in expanding on the current results gleaned from the Brookhaven LabSBUESnet collaboration, which in April 2019 achieved the longest distance entanglement distribution experiment in the United States by covering approximately 20 km. Integral to the testbed are room-temperature quantum network prototypes, developed by SBUs Quantum Information Technology (QIT) laboratory, that connect several quantum memories and qubit sources. The combination of these important results allowed the BrookhavenSBU ESnet team to design and implement a quantum network prototype that connects several locations at Brookhaven Lab and SBU.

By using quantum memories to enhance the swapping of the polarization entanglement of flying photon pairs, the implementation aims to distribute entanglement over long distances without detrimental losses. The team has established a quantum network on Long Island, N.Y., using ESnets and Crown Castle fiber infrastructure, which encompasses approximately 120-km fiber length connecting Brookhaven Lab, SBU, and Center of Excellence in Wireless and Information Technology (CEWIT) at SBU campus locations.

As a next step, the team plans to connect this existing quantum network with the Manhattan Landing (MAN- LAN) in New York City, a high-performance exchange point where several major networks converge. This work would set the stage for a nationwide quantum-protected information exchange network. Figure 3:3 depicts the planned network configuration.

Here are milestones called out in the report:

A fifth broad milestone the Cross-cutting milestone: Build a Multi-institutional Ecosystem emphasizes the importance of federal agency cooperation and coordination and names DOE, NSF, NIST, DoD, NSA, and NASA as key players. While pursuing these alliances, critical opportunities for new directions and spin-off applications should be encouraged by robust cooperation with quantum communication startups and large optical communications companies. Early adopters can deliver valuable design metrics.

Its a clearly ambitious agenda. Stay tuned.

Link to announcement, https://www.hpcwire.com/off-the-wire/doe-unveils-blueprint-for-the-quantum-internet-in-event-at-university-of-chicago/

Link to slide deck, https://science.osti.gov/-/media/ascr/ascac/pdf/meetings/202004/Quantum_Internet_Blueprint_Update.pdf?la=en&hash=8C076C1BEB7CA49A3920B1A3C15AA531B48BDD72

Link to full report, https://www.energy.gov/sites/prod/files/2020/07/f76/QuantumWkshpRpt20FINAL_Nav_0.pdf

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What's Needed to Deliver the Nationwide Quantum Internet Blueprint - HPCwire