Research is currently underway to develop a quantum internet, which could revolutionise certain fields. The technology is still in its early stages, with scientists focusing on fundamental questions such as the possibility of connecting systems and disseminating quantum states globally. The potential applications of this technology could be revolutionary, with many yet to be conceived. Quantum physicist Prof. Andreas Reiserer from the Technical University of Munich talks about the challenges of the Quantum Internet.
Nanjing University scientists have successfully demonstrated the storage and retrieval of entangled photons using 167Er3+ ions.
The researchers write in Nature Communications that the work is another step toward the development of a global quantum internet.
The team also points toward the technological challenges that need to be sorted out before the achievement of a quantum internet.
Image: Nanjing University/Nature Communications: Quantum storage of entangled photons at telecom wavelengths in a crystal
In a quantum communication technology advance, scientists at Nanjing University have successfully demonstrated the storage and retrieval of entangled photons using 167Er3+ ions, a step that could bring the world closer to realizing a global quantum internet.
Quantum networks would offer unprecedented levels of security and computational power, according to the researchers.
The study, published in Nature Communications, reports the use of 167Er3+ ions embedded in a crystal to store entangled photons—essential elements in quantum computing and secure communications—for 1.936 microseconds, a duration more than 387 times longer than previous attempts. This work was achieved by leveraging the naturally narrow linewidth of entangled photons and the long storage time offered by the ions.
“First, we show the storage of entangled photons in 167Er3+: Y2SiO5, a quantum memory at telecom wavelength, which is a promising candidate for realizing an efficient, long storage time and broadband quantum memory,” the research team states, underscoring the potential of this approach in enhancing quantum memory systems.
The success of this experiment hinges on two key advancements. The first is the storage of entangled photons at telecom wavelengths, compatible with current fiber networks, in a solid-state device. The second is the integration of quantum memory with an entangled photon-pair source on a photonic chip, which is not only CMOS compatible but also suitable for scalable fabrication.
Security and Power
If a practical quantum internet could be achieved, communications would take a leap forward in security and computational power, the researchers report.
“The quantum internet—in synergy with the internet that we use today—promises an enabling platform for next-generation information processing, including exponentially speed-up distributed computation, secure communication, and high-precision metrology,” the researchers write.
More Work Needed
However, the team acknowledges that there is more work to do. They suggest that to enhance storage efficiency, future work could refine the atomic-frequency comb (AFC) parameters and employ more sophisticated initialization protocols that take advantage of the ions’ hyperfine structure. Moreover, integrating nanostructures could boost light-matter interactions, further extending the potential of 167Er3+ ions in quantum memory applications.
The study also points out that the complex level structure of 167Er3+ ions, while presenting challenges in optical pumping and coherent control pulse sequences, may also open new avenues for quantum engineering of photon-atom interactions.
Despite the technical complexities, the research represents a leap forward in quantum memory technology. The team is optimistic that with further experimental enhancements, 167Er3+ ions combined with integrated quantum photonics could become a robust platform for high-performance quantum memory systems. And that could pave the way for large-scale quantum networks.
The research team included: Ming-Hao Jiang, Wenyi Xue, Qian He, Yu-Yang An, Xiaodong Zheng, Wen-Jie Xu, Yu-Bo Xie, Yanqing Lu, Shining Zhu and Xiao-Song Ma.
Microsoft and Photonic Inc. have announced a strategic collaboration to advance quantum networking and computing. The partnership will combine Photonic's spin-photon architecture, which supports quantum communication over standard telecom wavelengths, with Microsoft's Azure infrastructure. The aim is to integrate quantum networking capabilities into everyday operating environments. Jason Zander, Executive Vice President of Strategic Missions and Technologies at Microsoft, and Dr. Stephanie Simmons, founder and Chief Quantum Officer of Photonic, highlighted the potential of the collaboration to accelerate scientific discovery and innovation in quantum computing. The partnership will focus on three stages of quantum networking, including the development of a reliable quantum repeater.
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BTQ Technologies Inc., a global quantum technology company, has announced the addition of Dr. Peter Rohde, a renowned theoretical quantum computer scientist and Quantum Internet Expert, to its technical team. Dr. Rohde, an Honorary Senior Lecturer at Macquarie University and Associate Investigator at the ARC Centre of Excellence for Engineered Quantum Systems, is known for his expertise in optical quantum computing, quantum networking, and the economics of quantum technology. He will join Prof. Gavin Brennen, BTQ's Head of Quantum Research, in Sydney to drive research and expand BTQ's technical team in Australia.
Aliro Quantum has secured Accenture Ventures and Leaders Fund funding to advance its quantum networking technology. The investment will boost Aliro's ability to help various sectors design and deploy secure networks based on quantum entanglement.
Researchers from the University of York along with the Quantum Communications Hub and euNetworks Fiber UK successfully executed quantum communication between the UK and Ireland, marking a first in history. The team employed euNetworks' Rockabill subsea cable for the endeavor. Quantum communication offers potential for future security measures for private data by collapsing if interfered. The research boosts the use of Quantum Key Distribution, a promising data encryption technology.
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The popular children's game of telephone is based on a simple premise: The starting player whispers a message into the ear of the next player. That second player then passes along the message to the third person and so on until the message reaches the final recipient, who relays it to the group aloud. Often, what the first person said and the last person heard are laughably different; the information gets garbled along the chain.
Such transmission errors from start to end point are also common in the quantum world. As quantum information bits, or qubits (the analogs of classical bits in traditional digital electronics), make their way over a channel, their quantum states can degrade or be lost entirely. Such decoherence is especially common over longer and longer distances because qubits — whether existing as particles of light (photons), electrons, atoms, or other forms — are inherently fragile, governed by the laws of quantum physics, or the physics of very small objects. At this tiny scale (nanoscale), even slight interactions with their environment can cause qubits to lose their quantum properties and alter the information they store. Like the game of telephone, the original and received messages may not be the same.
"One of the big challenges in quantum networking is how to effectively move these delicate quantum states between multiple quantum systems," says Scott Hamilton, leader of MIT Lincoln Laboratory's Optical and Quantum Communications Technology Group, part of the Communications Systems R&D area. "That's a question we're actively exploring in our group."
As Hamilton explains, today's quantum computing chips contain on the order of 100 qubits. But thousands, if not billions, of qubits are required to make a fully functioning quantum computer, which promises to unlock unprecedented computational power for applications ranging from artificial intelligence and cybersecurity to health care and manufacturing. Interconnecting the chips to make one big computer may provide a viable path forward. On the sensing front, connecting quantum sensors to share quantum information may enable new capabilities and performance gains beyond those of an individual sensor. For example, a shared quantum reference between multiple sensors could be used to more precisely locate radio-frequency emission sources. Space and defense agencies are also interested in interconnecting quantum sensors separated by long ranges for satellite-based position, navigation, and timing systems or atomic clock networks between satellites. For communications, quantum satellites could be used as part of a quantum network architecture connecting local ground-based stations, creating a truly global quantum internet.
However, quantum systems can't be interconnected with existing technology. The communication systems used today to transmit information across a network and connect devices rely on detectors that measure bits and amplifiers that copy bits. These technologies do not work in a quantum network because qubits cannot be measured or copied without destroying the quantum state; qubits exist in a superposition of states between zero and one, as opposed to classical bits, which are in a set state of either zero (off) or one (on). Therefore, researchers have been trying to develop the quantum equivalents of classical amplifiers to overcome transmission and interconnection loss. These equivalents are known as quantum repeaters, and they work similarly in concept to amplifiers, dividing the transmission distance into smaller, more manageable segments to lessen losses.
"Quantum repeaters are a critical technology for quantum networks to successfully send information over lossy links," Hamilton says. "But nobody has made a fully functional quantum repeater yet."
The complexity lies in how quantum repeaters operate. Rather than employing a simple "copy and paste," as classical repeaters do, quantum repeaters work by leveraging a strange quantum phenomenon called entanglement. In quantum entanglement, two particles become strongly connected and correlated across space, no matter the distance between them. If you know the state of one particle in an entangled pair, then you automatically know the state of the other. Entangled qubits can serve as a resource for quantum teleportation, in which quantum information is sent between distant systems without moving actual particles; the information vanishes at one location and reappears at another. Teleportation skips the physical journey along fiber-optic cables and therefore eliminates the associated risk of information loss. Quantum repeaters are what tie everything together: they enable the end-to-end generation of quantum entanglement, and, ultimately, with quantum teleportation, the end-to-end transmission of qubits.
Ben Dixon, a researcher in the Optical and Quantum Communications Technology Group, explains how the process works: "First, you need to generate pairs of specific entangled qubits (called Bell states) and transmit them in different directions across the network link to two separate quantum repeaters, which capture and store these qubits. One of the quantum repeaters then does a two-qubit measurement between the transmitted and stored qubit and an arbitrary qubit that we want to send across the link in order to interconnect the remote quantum systems. The measurement results are communicated to the quantum repeater at the other end of the link; the repeater uses these results to turn the stored Bell state qubit into the arbitrary qubit. Lastly, the repeater can send the arbitrary qubit into the quantum system, thereby linking the two remote quantum systems."
To retain the entangled states, the quantum repeater needs a way to store them — in essence, a memory. In 2020, collaborators at Harvard University demonstrated holding a qubit in a single silicon atom (trapped between two empty spaces left behind by removing two carbon atoms) in diamond. This silicon "vacancy" center in diamond is an attractive quantum memory option. Like other individual electrons, the outermost (valence) electron on the silicon atom can point either up or down, similar to a bar magnet with north and south poles. The direction that the electron points is known as its spin, and the two possible spin states, spin up or spin down, are akin to the ones and zeros used by computers to represent, process, and store information. Moreover, silicon's valence electron can be manipulated with visible light to transfer and store a photonic qubit in the electron spin state. The Harvard researchers did exactly this; they patterned an optical waveguide (a structure that guides light in a desired direction) surrounded by a nanophotonic optical cavity to have a photon strongly interact with the silicon atom and impart its quantum state onto that atom. Collaborators at MIT then showed this basic functionality could work with multiple waveguides; they patterned eight waveguides and successfully generated silicon vacancies inside them all.
Lincoln Laboratory has since been applying quantum engineering to create a quantum memory module equipped with additional capabilities to operate as a quantum repeater. This engineering effort includes on-site custom diamond growth (with the Quantum Information and Integrated Nanosystems Group); the development of a scalable silicon-nanophotonics interposer (a chip that merges photonic and electronic functionalities) to control the silicon-vacancy qubit; and integration and packaging of the components into a system that can be cooled to the cryogenic temperatures needed for long-term memory storage. The current system has two memory modules, each capable of holding eight optical qubits.
To test the technologies, the team has been leveraging an optical-fiber test bed leased by the laboratory. This test bed features a 50-kilometer-long telecommunications network fiber currently connecting three nodes: Lincoln Laboratory to MIT campus and MIT campus to Harvard. Local industrial partners can also tap into this fiber as part of the Boston-Area Quantum Network (BARQNET).
"Our goal is to take state-of-the-art research done by our academic partners and transform it into something we can bring outside the lab to test over real channels with real loss," Hamilton says. "All of this infrastructure is critical for doing baseline experiments to get entanglement onto a fiber system and move it between various parties."
Using this test bed, the team, in collaboration with MIT and Harvard researchers, became the first in the world to demonstrate a quantum interaction with a nanophotonic quantum memory across a deployed telecommunications fiber. With the quantum repeater located at Harvard, they sent photons encoded with quantum states from the laboratory, across the fiber, and interfaced them with the silicon-vacancy quantum memory that captured and stored the transmitted quantum states. They measured the electron on the silicon atom to determine how well the quantum states were transferred to the silicon atom's spin-up or spin-down position.
"We looked at our test bed performance for the relevant quantum repeater metrics of distance, efficiency (loss error), fidelity, and scalability and found that we achieved best or near-best for all these metrics, compared to other leading efforts around the world," Dixon says. "Our distance is longer than anybody else has shown; our efficiency is decent, and we think we can further improve it by optimizing some of our test bed components; the read-out qubit from memory matches the qubit we sent with 87.5 percent fidelity; and diamond has an inherent lithographic patterning scalability in which you can imagine putting thousands of qubits onto one small chip."
The Lincoln Laboratory team is now focusing on combining multiple quantum memories at each node and incorporating additional nodes into the quantum network test bed. Such advances will enable the team to explore quantum networking protocols at a system level. They also look forward to materials science investigations that their Harvard and MIT collaborators are pursuing. These investigations may identify other types of atoms in diamond capable of operating at slightly warmer temperatures for more practical operation.
The nanophotonic quantum memory module was recognized with a 2023 R&D 100 Award.
A packaged prototype quantum repeater module (center), mounted on a gold-plated copper assembly and connected to printed circuit boards (green), features eight optical memories that store qubits in a silicon atom in diamond.
Signal loss over fiber means that satellites are required to create the global quantum internet.
TNO and the Institute of Communication and Computer Systems (ICCS), along with a consortium of other European partners, join forces for the “Leap in Advancing of critical Quantum key distribution-space components” project.
The project’s goals are to advance the technical building blocks, make the technology suitable for space and develop the next critical technologies.
PRESS RELEASE — The future global quantum internet is blocked due to signal losses in fiber over distance. Satellites are required so that cities and continents can be connected to eventually be part of the global quantum internet and fully benefit from its promising applications.
To provide for this, TNO and the Institute of Communication and Computer Systems (ICCS) and a consortium of other European partners, join forces in the LaiQa-project (Leap in Advancing of critical Quantum key distribution-space components). This was announced recently in Berlin.
Kees Buijsrogge, Director TNO Space: “By combining TNO’s expertise in the field of quantum, classical networks and free space optics with the expertise or our European partners, we’re confident we can develop the space technology to make it happen.”
Because of their unprecedented computational power, quantum computers will offer new possibilities for innovation. In the coming decades, they are expected to solve some of the biggest challenges humankind is facing in for instance medicine discovery, material design, predictive analysis. To unlock its full potential, it is necessary to connect quantum computers and devices all over the world via a quantum internet using photons as the carriers of quantum information. However, the advent of a global quantum internet is blocked as fiber-based quantum communication is limited to a few hundreds of kilometers due to losses over distance. Therefore the use of satellites offers a promising solution to overcome the limitations over national and continental scales, and eventually enable a worldwide quantum internet.
Quantum Internet From Space
To enable quantum internet from space, the LaiQa project has several objectives. First it will further advance the technical building blocks required to set up a quantum communication. Next to that it’s necessary to make them suitable for use in space and test their integration in the lab and outside, in a long distance free-space-to-fiber setup. Furthermore LaiQa aims to develop the necessary critical technologies. Specifically it focusses on three different photon sources, a quantum memory fit for long distance communication, an advanced fiber-coupling/adaptive optics system to interface satellites and ground stations, and software components to optimize the system architecture.
Quantum Key Distribution
The project will also demonstrate an example of quantum communication, called Quantum Key Distribution (QKD). QKD is considered as a first application of the Quantum Internet and is an ultra-secure way to share encryption keys between distant users. The demo will take place in lab conditions, in a terrestrial free-space optical testbed, and eventually in an in-field demonstration using the Greek Helmos optical ground station. LaiQa will also propose specifications standards on space components for QKD, in order to ease and foster the uptake of further activities in the field.
European Cooperation
Funded by the European Union, the project is expected to start in the beginning of 2024 and run for 3 years. It will be led by the Institute of Communication and Computer Systems (ICCS) from Athens. Besides TNO, other involved partners are qtlabs – Quantum Technology Laboratories GmbH (Austria), qssys – Quantum Space Systems GmbH (Germany), the National Observatory of Athens, Eindhoven University of Technology, the National and Kapodistrian University of Athens, and Thales Alenia Space Italia.
The Quantum Internet Alliance (QIA) has launched its first Quantum Internet Application Challenge, inviting quantum enthusiasts to contribute to the future of quantum internet. The challenge requires participants to develop an innovative application that utilises quantum network functionalities, using QIA's application simulator SquidASM. The main prize includes an internship or research visit to one of QIA's partners in Germany, the Netherlands, or Italy. The challenge is open for registration from 12 September until 23 October 2023. QIA, led by QuTech, a collaboration of Delft University of Technology and TNO, is a consortium of around 40 institutions aiming to build a global Quantum Internet.
The Quantum Internet Alliance launches a challenge to encourage quantum enthusiasts shape the future of the quantum internet.
The Challenge is to come up with an innovative idea for an application that utilizes quantum network functionalities.
Winners of the main challenge will receive an internship or research visit to one of QIA’s prestigious partners.
PRESS RELEASE — The Quantum Internet Alliance (QIA) has announced the launch of its first ever Quantum Internet Application Challenge, an initiative encouraging quantum enthusiasts to take part in shaping the future of the quantum internet.
“The role of the community—from students and enthusiasts to scientists and industry leaders—in our mission of building a global quantum internet is pivotal. And the Quantum Internet Application Challenge is a platform for us to welcome innovative ideas from the community and give an opportunity to co-create a future powered by the quantum internet,” QIA Director Stephanie Wehner noted.
QIA welcomes the participation of all individuals that are interested in quantum and have pioneering application ideas that harness the potential of quantum networks. While some familiarity with programming in python is needed to take part in the challenge, participants are encouraged to participate regardless of their technical background.
The Main Challenge
The Challenge is to come up with an innovative idea for an application that utilizes quantum network functionalities. The goal is to demonstrate this idea with a prototype by using SquidASM to simulate the quantum functionality. QIA’s application simulator SquidASM is an SDK developed by QIA partner QuTech specifically to simulate quantum networking applications. This toolkit provides a selection of quantum primitives, enabling participants to integrate existing elements or devise advanced protocols.
Eligible entries should present a clear application idea and a refined software prototype. Submissions will be evaluated based on novelty, creativity, technical sophistication, and documentation clarity.
Quantum Network Explorer Application Challenge for beginners
Under this initiative, QIA also offers a beginner’s challenge for those who want to learn the basics of quantum networking, are new to programming in python or have limited time to spend on a challenge.
This beginner’s challenge requires participants to upload their own quantum network application to Quantum Network Explorer (QNE) Community Application Library, a platform co-developed by QIA. This can be as simple as copying as a template an existing application with modified input/output parameters, an implementation of a quantum protocol, or something completely new.
The Prize
The prize for the main challenge offers an internship or research visit to one of the following participating QIA partners:
Quantum Communication and Cryptography group of Anna Pappa / Berlin (Germany)
Quantum Computer Science group of Stephanie Wehner / Delft (The Netherlands)
Quantum Software Lab of Michele Amoretti / Parma (Italy)
QIA will cover travel and accommodation costs of up to 5,000 EUR. Winners for the beginner’s challenge, on the other hand, will receive QNE goodie bags and gift vouchers.
The Quantum Internet Application Challenge is open for registration from 12 September and submissions will be accepted until 23 October 2023. QIA will announce the winners in early-November.
“The Quantum Internet Application Challenge reflects QIA’s commitment to innovation and collaboration. We welcome participants from diverse backgrounds to pitch their expertise and ideas, and be part of our shared mission to shape the quantum landscape,” Wehner concluded.
For more information on the Quantum Internet Application Challenge, click here.
The U.S. Department of Energy (DOE) announced $24 million in funding for quantum network research.
Scientific research infrastructure linked with quantum networks is needed to realize distributed quantum computers.
Projects will be led by Argonne National Laboratory, Oak Ridge National Laboratory and Fermi National Accelerator Laboratory.
Image: Department of Energy’s Office of Science
PRESS RELEASE — The U.S. Department of Energy (DOE) announced $24 million in funding for three collaborative projects in quantum network research.
Scientific research infrastructure linked with quantum networks is needed to realize distributed quantum computers. These quantum computers could simulate complex scientific processes inaccessible to computational platforms of today, integrate quantum sensors that promise measurements of unprecedented precision, and address previously inaccessible scientific questions of importance.
“Advances in quantum networking are enabling effective interconnections among multiple quantum devices,” said Ceren Susut, DOE Acting Associate Director of Science for Advanced Scientific Computing Research. “However, realizing scalable infrastructures for quantum information flows demands advancements in devices, error mitigation techniques, and new quantum network architectures and protocols.”
Projects include:
A collaborative research effort led by Argonne National Laboratory, partnering with the Northwestern University, the University of Chicago, the University of Illinois-Urbana-Champaign, and Fermi National Accelerator Laboratory, following a heterogeneous, full-stack approach in codesigning scalable quantum networks.
A collaborative research effort led by Oak Ridge National Laboratory, partnering with the University of Massachusetts-Amherst, the University of Arizona, and the Arizona State University, developing the architecture and protocols for a performance-integrated scalable quantum internet.
A collaborative research effort led by Fermi National Accelerator Laboratory, partnering with the California Institute of Technology, the University of Illinois-Urbana-Champaign, the Northwestern University, and Argonne National Laboratory, developing hyper-entanglement-based networking and error noise-robust correction techniques for developing advanced quantum networks for science discovery.
Total funding is $24 million for projects lasting up to three years in duration, with $8 million in Fiscal Year 2023 dollars and outyear funding contingent on congressional appropriations. The list of projects and more information can be found on the Advanced Scientific Computing Research program homepage.
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