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Quantum Networks Town Hall andDomestic Cooperation WorkshopFebruary 27-28, 2025The SUNY Global Center Message

WELCOMEA message from the NQVL SCY-QNet team:Dear colleagues,Five years ago in 2020, the Quantum Network community met inSUNY Global to prepare the first document regarding a vision todevelop a Quantum Internet in the United States.This week, we will meet to celebrate the achievements of ourcommunity in building this vision across many efforts across thenation. We will also look forward to envisioning what is coming in thenear future and what is needed to interconnect our different efforts. We look forward to a successful meeting and fruitful discussions.Kind regards,Eden Figueroa (on behalf of the SCY-QNet team and the QNDCcommittee)

In this SCY-QNet Town Hall, we will explore how to coordinate a federatedquantum network infrastructure and establish mechanisms to enablemembers to use the SCY-QNet virtual laboratory. Our SCY-QNet TownHall meeting seeks community input to foster open scientific dialogue, tocollect baseline data to aid in the development of a diverse workforcedevelopment plan, and to ensure the broad participation of the entireQISE community. As part of this gathering, we will host the first QuantumNetworking Domestic Cooperation (QNDC) meeting on the second day ofthe Town Hall.The outcomes of this event will be: 1. Addressing the specific requirements of functional quantum networks 2. Refining the science questions regarding building quantum repeaters 3. Identifying enabling quantum communication and network technologies, risks, and gaps 4. Identifying critical partnerships and dependencies to carry on the construction of SCY-QNetPURPOSE

Welcome and Opening RemarksNina MaungSenior Associate Vice President forResearch Development and PartnershipsStony Brook UniversityShadi Shahedipour-SandvikSenior Vice Chancellor for Research,Innovation and Economic DevelopmentState University of New York Kevin GardnerVice President for Research and InnovationStony Brook UniversityChang Kee JungSUNY Distinguished Professor Chair, Department of Physics and AstronomyStony Brook University

Invited Speakers

Jian-Wei Pan University of Science and Technology of ChinaBased on state-of-the-art fiber technology and rich fiber resources, we have managedto achieve prevailing quantum communication with realistic devices in real-lifesituation. This constitutes demonstrations by developing decoy state scheme over100km firer, extending its employment in the metropolitan area network, as well asmaintaining Measurement Device Independent QKD (MDI-QKD) over 400km. At themeantime, we are also developing practically useful quantum repeaters that combineentanglement swapping, entanglement purification, efficient and long-lived quantummemory for the ultra-long distance quantum communication. Anothercomplementing route is to attain global quantum communication based on satellite.We have spent the past decade in performing systematic ground tests for satellite-based quantum communications. Our efforts finally ensure a successful launch of theMicius satellite. Three major scientific missions have been finished, which includesachieving QKD between satellite and ground station at thousand-kilometer scale,achieving satellite-based entanglement distribution between two ground stationsseparated by a distance of 1200 km, achieving quantum teleportation from ground tosatellite over 1400 km. Future Prospects include building a global quantum communication infrastructurewith satellite and fiber networks, enormous spatial resolution and global precisetiming information sharing networks with applications for the global quantumcommunication network, ultra-precise optical clocks in outer space to detectgravitational wave signal with lower frequency.Dream or Reality? Quantum Communication: The Past, Present and Beyond

Alexander Ling Centre for Quantum Technologies National University of SingaporeIn this session, I will give an overview of Singapore'sresearch and development efforts in building longdistance quantum networks. This will include our plansfor testing entanglement distribution using smallsatellites, and also the community's recent work intesting entanglement distribution across optical fibernetworks.Entanglement Distribution Technologies For a Quantum-Safe Network

Val Zwiller KTH Royal Institute of TechnologyThe ability to detect single photons is crucial for quantum optics as well as for a widenumber of applications. Several technologies have been developed for efficientsingle photon detection in the visible and near infrared. The invention of thesuperconducting nanowire single photon detector in 2001 enabled the developmentof a new class of detectors that can operate close to physical limits. Different aspectswill be discussed including wavelength detection range, time resolution, dark counts,saturation rates and photon number resolution along with various applications suchas Lidar, quantum communication, deep space communication, microscopy and bio-medical measurements. Multipixel single photon detectors based on superconducting nanowires will also bediscussed, including a quantum spectrometer that is based on an array of high-performance single photon By time stamping single photon detection events at theoutput of a spectrometer we generate data that can yield spectra as well as photoncorrelations such as g(2), g(3) to g (n) as well as cross correlations among differentspectral lines, under pulsed excitation, transition lifetimes can also be extracted. Thisinstrument therefore replaces a spectrometer, a streak camera, a Hanbury-BrownTwiss interferometer and operates with far higher signal to noise ratio than is possiblewith existing detectors that are commonly used in the infrared.Detecting Light at the Single Photon Level: Quantum Devices and Applications

Jürgen Eschner Saarland UniversityWe report on the characterization and operation of a 14-km long telecom fiber link forquantum communication. The dark fiber extends across the town of Saarbrücken,Germany, connecting our labs at the University (UdS) with a server room at theTechnical University (htw). It has underground and overground sections and ~ 9 dBattenuation, including one lossy splice. We stabilize its polarization with > 99%process fidelity up to 60 s. For implementing quantum communication protocols, weemploy a 40Ca+ single-ion quantum memory, an SPDC-based ion-resonant entangledphoton-pair source, and quantum frequency conversion from the ionic wavelength of854 nm to the telecom C-band. We demonstrate quantum communication protocolscomprising (i) the distribution of photonic entanglement via the fiber link, (ii) thegeneration of distant ion-photon entanglement via quantum state-preservingheralded absorption of one photon of an entangled pair and transmission of thepartner photon to the htw, and (iii) quantum state teleportation from a memory qubit,encoded in the ion’s spin state, onto a 1550-nm photonic qubit at the htw [1]. In alaboratory experiment we also realize building blocks of a quantum repeater based ontwo co-trapped 40Ca+ ions that are entangled with their emitted photons. By aMølmer-Sørensen quantum gate on the ions, we swap entanglement ontoasynchronously generated photons [2]. By a Bell measurement on two photons,employing their Hong-Ou-Mandel interference, we swap entanglement onto the twoemitting ions. [1] S. Kucera et al., npj Quantum Information 10, 88 (2024) [2] M. Bergerhoff et al., Phys. Rev. A 110, 032603 (2024)Quantum Communication Protocols Over a 14-km Urban Fiber Link

Klaus Jöns Paderborn UniversityEurope is making significant strides in realizing quantum networkinfrastructure, transitioning from local testbeds to a coordinated, cross-border initiative. Germany has started more than a decade ago to invest in aplatform-agnostic approach to quantum repeaters, funding multipletechnological pathways, including semiconductor-based quantum dots as oneof the brightest quantum light sources. I will highlight some of the remarkableachievements based on quantum dots and discuss the feasibility of on-demand generation of entangled photon pairs for quantum repeatersarchitectures that integrate external quantum memories. Additionally,Germany has invested in local testbeds, such as the one in Paderborn, while anew EU-wide initiative will co-funding nationwide testbed deployments thatutilize heralded memory-memory entanglement over telecom fiber. A criticalenabler of this progress is Germany’s Deutsche Telekom dark fiber network,already providing connectivity between major cities for quantumcommunication applications. These developments position Europe as a globalleader in quantum networks and highlight the potential for internationalcollaboration and knowledge exchange, fostering a global ecosystem forquantum networks. Photo by Besim Mazhiqi, Paderborn UniversityAdvancing Quantum Networks in Germany and Europe:From Local Testbeds to a Continental Infrastructure

Don Towsley University of Massachusetts AmherstQuantum information processing is at the threshold of having significant impact ontechnology and society in the form of providing unbreakable security, ultra-high-precision distributed sensing, and polynomial/exponential speed-ups in computing.Many of these applications are enabled by high rate distributed shared entanglementbetween pairs and groups of users. A critical missing component that preventscrossing this threshold is a distributed infrastructure in the form of a world-wide“Quantum Internet”. This motivates the study of quantum networks, namely, toidentify the right architecture and how should it operate, e.g., dynamic fair allocationof resources. Moreover, the architecture and network operation must account foroperation in harsh, noisy environments. Two quantum network architectures have been proposed and widely studied. Theseare the two-way and one-way architectures, aka 1-st generation and 3-rd generation.The service provided by a two-way network is to generate and distribute quantumentanglement to pairs or groups of users whereas a one-way network allows for directtransfer of quantum information from one user to another. In this talk we will presentand make a comparison between both architectures. Finding the two-wayarchitecture superior, we will then present a “connectionless” version that allows usto easily adapt classical network and transport protocols to a quantum network. Wewill provide several examples of this and conclude with several open researchquestions.Quantum Networks: Recent Advances and Challenges

Paul Kwiat University of Illinois Urbana-ChampaignJust as our classical communication networks rely onfree-space channels in addition to optical fiber links, it islikely that eventual quantum networks will require bothwired (fibers) and wireless (free-space) connectivity. HereI’ll discuss some of the potential of such hybrid networks,as well as the challenges, and our current efforts toaddress the latter and realize the former.The Promise and Peril of Wireless Quantum Communications

Eden Figueroa Stony Brook UniversityThe Quantum Internet (QI) concept was proposed in the late 2000s,inspired by advancements in network technologies and light-matterquantum interfaces. It is based on interconnecting quantum nodes,including quantum memories (QM) and entanglement sources, todistribute quantum entanglement between quantum network (QN)nodes.In this talk, we will discuss the Stony Brook – Columbia -Yale quantumnetwork (SCY-QNet), aimed at creating a 10-node, 350 km long quantuminternet prototype connecting advanced quantum processing unitsusing quantum repeaters. We will present first experimental results ofthis collaboration, including the connection of room temperaturequantum memories operating at telecom wavelengths and thedistribution of polarization entanglement across 140 km, using the real-world quantum network connecting Stony Brook University, BrookhavenNational Laboratory and the Commack Data Center.Building the Quantum Internet: The SCY-QNet Collaboration

Brian SmithUniversity of OregonIn this talk I will describe the basis for the ASPEN-Net,which is focused on phase-stabilized optical links andsingle-photon path entanglement distribution. Thistype of quantum network architecture is well suitedto quantum-enhanced long baseline interferometry(QVLBI) as an application. I will highlight our recentprogress towards realization of QVLBI and futureplans with ASPEN-Net.ASPEN-Net - Attosecond Synchronized PhotonicEntanglement Network

Ebrahim KarimiUniversity of OttawaOver the past decade, the University of Ottawa team has studied the useof structured photons—electromagnetic fields with spatially varyingspatiotemporal properties, including polarisation, orbital angularmomentum, radial, and temporal states—for free-space, underwater, andfibre-based communication channels. These structured photons enableaccess to high-dimensional Hilbert spaces, significantly enhancing channelcapacity and resilience to noise. Furthermore, they provide access to novelcommunication protocols that go beyond traditional qubit-basedtechniques.In my talk, I will provide an overview of our recent advancements,including developing novel protocols. I will focus on the challengesintroduced by atmospheric turbulence in free-space channels and ourstrategies for mitigating its effects. Specifically, I will discuss how datacollected from our 5.4 km free-space channel was utilised to train a neuralnetwork to predict turbulence-induced distortions and how adaptiveoptics can be employed to restore quantum states, ensuring therobustness of high-dimensional quantum communication.High-Dimensional Quantum Communication Channels and Their Challenges

Joseph Lukens Purdue UniversityThe seemingly endless success of the classical internetprovides an attractive template for scaling up quantuminformation processing systems. Yet the technologicalchallenges associated with establishing entanglement over thedistances, bandwidths, and reliability now routine in theclassical internet place many roadblocks in front of this vision.In this talk, I will overview the origins and status of deployedquantum networking, emphasizing domestic accomplishmentsand opportunities. Incorporating case studies in flex-gridquantum networks and suggesting community milestones bywhich to gauge future research, I will argue that—far from apipe dream—the groundwork for the quantum informationsuperhighway is already being laid.Paving the Quantum Information Superhighway: Progress, Roadblocks, and Opportunities

Sebastian WillColumbia UniversityAtomic tweezer arrays are one of the fastest growing quantumcomputing platforms. In our group we realize atomic tweezerarrays of ultracold strontium atoms, which feature internalstates with long coherence time and enable high fidelityRydberg gates. In this talk, I will discuss our recent advances inrealizing large atomic Sr arrays via holographic metasurfaces[1], enabling arrays with >1000 atomic qubits and facilitatingphotonic integration. We work on coupling these arrays withfiber Fabry-Perot cavities, fabricated in a new foundry at BNL.Such cavity coupled arrays will be ideally suited to establishremote entanglement at high rates and realize a quantumnetwork of atomic quantum devices. [1] A. Holman, Y. Xu, X. Sun, J. Wu, M. Wang, B. Soe, N. Yu, and S. Will,arXiv:2411.05321 (2024)SCY-QNET: Building Quantum-Compatible Quantum Processing Units

Erhan SaglamyurekLawrence Berkeley National LaboratoryThe QUANT-NET project, supported by DOE, aims to build aquantum network testbed in the Berkeley area in collaborationwith Lawrence Berkeley National Lab, University of California,Berkeley (UCB), and Caltech. In this talk, we will introduce thecore technologies of QUANT-NET and present our progresstowards realization of an elementary network of quantumprocessing units that include trapped ions and color-centers insilicon. QUANT-NET: A Distributed Quantum Computing Testbed in the Berkeley Area

Chaohan CuiUniversity of MarylandThe NSF-funded Gen-4 ERC Center for QuantumNetworks (CQN) is now in its 5th year, awaiting renewalfor the next five years. CQN supports a broad spectrumof research with three testbeds: the fast-developingBoston testbed, the young Tucson Testbed, and therecently planned Maryland Testbed. In this talk, I willbriefly summarize the architecture and mission of alltestbeds, recent experimental and theoretical progress,and predicted milestones for the future.NSF Center for Quantum Networks: Now and Next

Erin SheridanAir Force Research LaboratoryThe quantum information sciences branch at AFRL aims toadvance photonic, trapped ion and superconducting qubittechnologies and to construct a heterogeneous quantumnetwork to connect them. Quantum transduction betweenmicrowave and optical frequencies is necessary for theintegration of superconducting qubits into large-scalequantum networks. In this talk, we will detail our experimentsdemonstrating microwave-to-optical transduction at 10 milli-Kelvin. Finally, we will discuss our team’s efforts to construct aheterogeneous quantum network testbed connecting differentqubit species, and the goals we have for that network.Heterogeneous Quantum Networks at AFRL

Krister ShalmNational Institute of Standards and TechnologyThe Boulder quantum networking test bed is focused onbuilding a scalable all-optical quantum repeater usingtechnologies that exist today. This partnership between NIST,the University of Colorado, at the ASPEN-Net team aims todemonstrate high-rate and high-quality entanglementdistribution that can operate with a quantum advantage. Inthis talk I will discuss our efforts to build quantum-compatiblephase-stabilization technologies, new photon sources suitablefor use in a path-entangled network, and our development ofdevice-independent quantum communication protocols thatcan be run on this network.The Boulder Path Towards All-Optical Quantum Networks

Mehdi NamaziQunnect, Inc.In this talk I will briefly go over GothamQ and the workQunnect has been doing in New York City To enable theinfrastructure for large scale quantum networks. Ourunique hardware allows us and our partners to useentanglement in a robust, 24/7 fashion, towardsapplications in quantum repeating, distributed quantumsensing, and computing. I will also discuss our latestresults on the testbed and talk about the upcomingprojects. GothamQ: Entangling New York City

Hybrid quantum-classical networks are poised to revolutionize securecommunication, quantum computing, and quantum sensing by enablingquantum entanglement-based services within a memory-assistedquantum repeater framework. To support these capabilities, aheterogeneous network architecture will be necessary, incorporatingboth fiber-optic and free-space links. This talk will explore the criticaltechnologies and strategies required to realize long-distance, distributedquantum information processing, detailing the challenges andadvancements needed to achieve this ambitious vision. Julian Martinez-RinconBrookhaven National Laboratory Enabling Technologies for Long-Distance Quantum Networking Quantum Network Testbeds in the US and Possible Gaps Quantum networking has experienced rapid growth in recent years,particularly in the United States, with an increasing number of testbedshighlighting its potential. In this discussion, I will explore the keyopportunities presented by these user facilities and identify criticalneeds that could enhance collaboration across the academic,government, and industry sectors

Ya-Shian Li-BaboudNational Institute of Standards and TechnologyQuantum networking protocols relying on interference and precisetime-of-flight measurements require high-precision clocksynchronization. The talk will cover the design, implementation,and characterization of two optical two-way time transfermethods in a metropolitan-scale quantum networking researchtestbed. Measurement methods are described to understand thesources of environmental fluctuations on clock synchronizationtowards the development of in-situ compensation methods. Pathdelay gradients, chromatic dispersion, polarization drift, andoptical power variations can contribute to clock synchronizationerrors. Research on solutions to advance quantum network-compatible optical two-way time transfer that addressesresilience, scalability, robustness, security and the ability to co-propagate timing signals in the quantum channel will be essentialfor enabling experimental research in developing practicalquantum networking protocols.DC-QNet Synchronization Infrastructure

Jordan ThomasNorthwestern University A long-standing goal towards large-scale quantum networks hasbeen to propagate quantum and classical communicationsthrough a single fiber, both enabling quantum networks to scalewithin the classically populated fiber infrastructure and forimplementing applications over real-world deployed fibers (eg.,quantum node clock synchronization). However, the challenges ofintegrating next-generation quantum applications with classicalsignals is under investigated. We discuss recent progress ondemonstrating advanced quantum operations like multi-channelentanglement distribution and the quantum teleportation ofsingle or entangled qubits in fibers carrying modern high-rate(>Tbps) and high power (>20 dBm) classical network traffic.Coexistence of Advanced Quantum and Classical OpticalCommunications in the Same Fiber Infrastructure

Thomas GerritsNational Institute of Standards and Technology As Quantum Networks (QN) and their applications areemerging, the need for QN metrics is also emerging. Thispresentation will cover an overview of QNs metricsthroughout the QN stack and should spark a discussionon the most pressing and long-term needs Metrics, Terms and Definitions

Dinner on 2/27 will be held at Cellini at 7:30 PM65 E 54th St, New York, NY 10022Cellini

On behalf of the SCY-QNet team and theQNDC committee, thank you for attending.Special thanks to: Guodong Cui Sonali Gera Susan RussoThe Office of Proposal Development at Stony Brook Universityfor their support and coordination of this event.