Monday, March 24, 2025

The University of Osaka and research partners launch open-source quantum computer OS

All-in-one OS developed in Japan is fully customizable from set-up through operation and is available via GitHub

Osaka University

Fig. 1 — image:
Overview of OQTOPUS
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Credit: OQTOPUS Team

Osaka, Kawasaki and Tokyo, Japan – The University of Osaka, Fujitsu Limited, Systems Engineering Consultants Co., LTD. (SEC), and TIS Inc. (TIS) today announced the launch of an open-source operating system (OS) for quantum computers on GitHub, in what is one of the largest open-source initiatives of its kind globally. The Open Quantum Toolchain for Operators and Users (OQTOPUS) OS can be customized to meet individual user needs and is expected to help make practical quantum computing a reality.

Until now, universities and companies seeking to make their quantum computers accessible via the cloud have had to independently develop extensive software to enable cloud-based operation. By offering this open-source OS —covering everything from setup to operation—the research partners have lowered the barrier to deploying quantum computers in the cloud.

Additionally, quantum computing cloud service offered by The University of Osaka has begun integrating OQTOPUS into its operations and Fujitsu Limited will make it available for research partners using its quantum computers in the second half of 2025.

Moving forward, the research team will drive the advancement of quantum computing through the continuous expansion of OQTOPUS’s capabilities and the development of a thriving global community. Dr. Keisuke Fujii at the Center for Quantum Information and Quantum Biology (QIQB) of The University of Osaka mentions, “this will facilitate the standardization of various quantum software and systems while driving the creation of innovative quantum applications."

Relativistic Heavy Ion Collider (RHIC) enters 25th and final run

Collisions of gold ions and other experiments will complete the RHIC science program and provide crucial insights for the future Electron-Ion Collider (EIC)

DOE/Brookhaven National Laboratory

RHIC tunnel — image:
Superconducting magnets inside the tunnel of the Relativistic Heavy Ion Collider (RHIC), a U.S. Department of Energy Office of Science user facility for nuclear research at Brookhaven National Laboratory. The collider is entering its 25th and final run before being transformed into a new facility, an Electron-Ion Collider.
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Credit: Kevin Coughlin/Brookhaven National Laboratory

UPTON, N.Y. — Silver is the traditional gift for 25th wedding anniversaries, but gold continues to be the element of choice for scientists conducting research at the Relativistic Heavy Ion Collider (RHIC). Today, this U.S. Department of Energy (DOE) Office of Science user facility for nuclear physics research at DOE’s Brookhaven National Laboratory entered its 25th and final year of operations, smashing together the nuclei of gold atoms traveling close to the speed of light.

RHIC first smashed gold ions in the summer of 2000. This year, RHIC physicists will complete data collection for one of the collider’s central goals: to create and study a unique form of matter known as a quark-gluon plasma, or QGP. This soup of the innermost building blocks of protons and neutrons last existed in nature some 14 billion years ago, just after the dawn of our universe, before those more familiar nuclear building blocks ever formed. By melting the boundaries of individual protons and neutrons, RHIC’s collisions set the quarks and gluons free, reliably recreating the primordial plasma so scientists can explore its inner workings.

In Run 25, scientists will use all the accelerator, detector, and data-capturing capabilities physicists have developed at RHIC over the past 25 years to probe the QGP with unprecedented precision.

“The evolution of RHIC has been nothing short of extraordinary,” said Jin Huang, a Brookhaven Lab physicist who was recently elected as co-spokesperson for RHIC’s newest detector, sPHENIX. “From its groundbreaking discoveries in creating and characterizing the quark-gluon plasma to its role in nurturing talent across the globe, RHIC has not only expanded the frontiers of nuclear science but also cultivated a deep, collaborative spirit among researchers. As we enter this final run, we carry forward the legacy of relentless inquiry, innovation, and mentorship that has defined RHIC’s journey.”

The highest priority for Run 25 will be gold-gold collisions at 200 billion electron volts (GeV). Those are expected to continue until at least early June, with a break from collisions in July and August to avoid operations in the challenging heat and humidity of summer. In mid-June, an advisory committee will assess how close the team is to meeting gold-gold data goals and discuss options for running additional types of collisions depending on available funding.

Interspersed with collisions, accelerator physicists plan to conduct accelerator physics experiments, or APEX studies, in 15-hour stints every two weeks to explore ways of improving accelerator performance. In the past, these studies have contributed substantially to dramatic improvements in RHIC’s collision rates, its ability to keep beams polarized, and other characteristics responsible for its remarkable success. APEX studies have also tested accelerator concepts crucial to the Electron-Ion Collider (EIC), America’s next collider, which will be built by reusing components of RHIC and adding new electron accelerator equipment.

“The APEX program has improved RHIC operations and upgrades, and in Run 25 it will play a crucial role in the design and future operation of the EIC,” said Haixin Huang, the Brookhaven Lab accelerator physicist who’s been leading this effort.

STAR goals for Run 25

RHIC’s STAR detector has been operational since RHIC’s beginning, with many upgrades culminating in 2022. Since then, its goals have been steady, including capturing as much data as possible from 200 GeV gold-gold collisions.

“From Runs 23 and 24, we collected 8 billion high-quality gold-gold collision events, and we aim to collect an additional 10 billion events this year,” said Brookhaven Lab physicist Lijuan Ruan, a co-spokesperson for the STAR experiment. “Additionally, we plan to leverage our detector’s ‘triggers’ — sensors that analyze characteristics from collisions in real time — to acquire a substantial number of events enriched with high-energy particles,” she said.

“With STAR’s improved ability to track particles emerging from collisions in the forward direction along the beamline — and record data at much higher rates than in RHIC’s early days — we hope to provide multiple measurements that will enable physicists to analyze them simultaneously instead of one variable at a time,” said Frank Geurts, a physicist at Rice University who is the other co-spokesperson for STAR. Using this “multimodal” approach and combining data from RHIC’s final three runs will help physicists explore global properties of the QGP, such as its temperature and ability to flow like a nearly friction-free “perfect” liquid.

sPHENIX aims for Run 25

For Run 25, the sPHENIX detector, which began operations in 2023, will be using all its capabilities for the first time to study the QGP produced in gold-gold collisions, with the goal of capturing data from 50 billion collision events.

“This new data set will allow sPHENIX scientists to study the QGP with remarkable accuracy using unique signals,” said sPHENIX co-spokesperson Megan Connors, a physicist at Georgia State University. “By combining these RHIC measurements with high-energy experiments at Europe’s Large Hadron Collider — which generates a QGP at higher temperatures — we’ll be able to refine our understanding of how this exotic matter behaves as its temperature changes.”

sPHENIX deploys precision particle tracking and the first “barrel hadronic calorimeter” at RHIC. These components identify different types of particles produced in collisions and measure the energy of particles emerging all around the point of collision. The data allow physicists to fully reconstruct “jets” of energetic particles emitted in each event — and study particles containing quarks that are heavier than those inside ordinary protons and neutrons.

“While events involving these heavy quarks are quite rare, the sPHENIX detector has been specifically designed to capture and identify a massive number of these events,” said co-spokesperson Jin Huang.

Since these heavy particles and jets are produced in the earliest stages of the collision and traverse the QGP as it evolves, they can both serve as probes for understanding the plasma’s properties. For example, a depletion, or “quenching,” of high energy jets has been a key signature of QGP formation since RHIC’s early days, with the understanding that jets “lose” energy through interactions with the QGP.

“Now we are diving deeper into studying these modifications in detail and testing the theoretical descriptions of energy loss in the QGP,” Connors said.

APEX studies for Run 25

The accelerator physics experiments proposed for Run 25 are entirely focused on understanding and mitigating challenges in the design of the EIC.

“Because this is the last year of RHIC operations, our goal is to make good use of available APEX beam time to answer critical questions related to the EIC design,” said Haixin Huang, the program leader and chair of the steering committee that decides which experiments to conduct.

Some of these APEX studies call for use of gold ion beams while others require accelerated protons. The highest priority experiments include studies to keep ion beams “flat” as they circulate through the collider and cross at an angle inside a detector — both of which will be essential to maximizing collision rates at the EIC. There will also be studies to understand how beams interact with one another with the aim of reducing effects such as intrabeam scattering, which can cause beams to expand and reduce collision rates.

“With a minimal amount of time — isolated 15-hour blocks every other week during the RHIC operational period — it’s essential that these experiments are well-planned so we can collect the data we need quickly and then get the machine ready for the next physics collisions,” Huang said.

Path forward

In addition to advancing scientists’ understanding of the hot nuclear matter generated in gold-gold collisions at RHIC, the data collected by, experience gained at, and technological advances incorporated into RHIC’s detectors are also helping to pave the way for future experiments at the EIC.

“From RHIC to EIC, scientists are mapping the transition of nuclear matter from a hot, dense state, generated in gold-gold collisions, and then planning to use electrons — the smallest projectiles — to probe cold nuclear matter at the EIC,” sPHENIX co-spokesperson Jin Huang noted.

Cold nuclear matter is the starting point for fully understanding what happens in RHIC collisions — what nuclei are made of before the ions collide. It’s also what makes up the visible matter of our world today — everything made of atoms, from planks of wood to planets, stars, and people. So, the research at the two facilities, though separated in time, will be highly complementary.

On the detector technology side, the sPHENIX hadronic calorimeter is slated for reuse in ePIC, the detector planned for the EIC. Cutting-edge monolithic active pixel sensors, first used in STAR and advanced further for sPHENIX, will be upgraded again for the EIC. And sPHENIX’s pioneering streaming readout data acquisition system, which has improved the precision of certain measurements by orders of magnitude, serves as a foundational model for the EIC data aqusition design.

“sPHENIX has also been an excellent opportunity for early career scientists to learn how to bring a new experiment to life from building, to commissioning, to operating new detector systems, to data collection, processing, and analysis,” Connors noted. “These skills will be crucial for commissioning and operating new detector systems at the EIC.”

As construction of that new facility begins in earnest at the conclusion of this year’s RHIC run, experimental nuclear physicists will have plenty to keep them busy.

“While our journey of data collection at RHIC will conclude after this run, the journey of discovery into the unknown will undoubtedly continue well into the next decade,” STAR’s Ruan reflected. Co-spokesperson Geurts agreed, saying, “STAR will continue to shine a bright light, guiding our work to better understand the fundamentals of nuclear matter. There is a lot waiting to be uncovered in the vast amounts of data that we will scrutinize in the years to come.”

Connors of sPHENIX further stressed that the journey is far from over, along with the importance of data longevity for nuclear physics:

“The raw data collected is just the beginning of a long process toward scientific discovery. We anticipate many exciting results from sPHENIX in the coming years,” she said. “In addition, all our data will be preserved to maximize the potential for future joint discoveries with the EIC.”

RHIC and the EIC are funded primarily by the DOE Office of Science.

Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov.

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USTC demonstrates successful satellite-enabled quantum key distribution

Chinese Academy of Sciences Headquarters

Schematic diagram of the quantum key distribution experiment between the quantum microsatellite Jinan-1 and ground stations — image:
Schematic diagram of the quantum key distribution experiment between the quantum microsatellite *Jinan-1* and ground stations
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Credit: Image by USTC

Quantum secure communication uses quantum mechanisms to secure classical (non-quantum) communication and is fundamental to national information security and socioeconomic development. One of the primary methods of quantum secure communication is quantum key distribution (QKD), which enables two parties to share an encryption key—typically over an insecure channel—while ensuring that any eavesdropping attempt can be detected. Although fiber-based QKD networks have achieved regional deployment, their long-distance use is limited by signal loss and coverage constraints.

Now, however, Chinese researchers have made a major breakthrough by developing the world's first quantum microsatellite and demonstrating real-time QKD between the satellite and multiple compact, mobile ground stations. In collaboration with researchers from South Africa—and using the satellite as a trusted relay—they demonstrated successful secure key sharing and encrypted communication between Beijing and Stellenbosch—two cities separated by 12,900 km.

The study, published in Nature on March 19, was conducted by PAN Jianwei, PENG Chengzhi, and LIAO Shengkai from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS), in collaboration with researchers from the Jinan Institute of Quantum Technology, the Shanghai Institute of Technical Physics (CAS), the Innovation Academy for Microsatellites (CAS), and Stellenbosch University in South Africa.

Satellite-based systems using free-space channel offer a viable alternative to fiber networks, potentially enabling QKD on a global scale. USTC pioneered this field with the Micius quantum satellite, achieving the world's first demonstration of space-to-ground QKD. This capability was later integrated with the fiber-based Beijing–Shanghai backbone, creating a space–ground quantum secure communication network.

For practical applications, however, compact payloads and portable ground stations are essential for widespread deployment and swift implementation. In particular, small-size payloads can be mounted on satellites of various sizes to form a quantum satellite internet constellation capable of providing global services.

Using these insights, the USTC team led the development of several key technologies, including miniaturized decoy-state QKD light sources, real-time key distillation and encrypted communication, and high-precision tracking. On July 27, 2022, Jinan-1, the world's first quantum microsatellite, was successfully launched. The research teams also developed compact optical ground stations, reducing the weight by two orders of magnitude to approximately 100 kg. This lightweight design allows for rapid deployment in different locations, significantly increasing flexibility and practicality.

Jinan-1 established optical links with multiple optical ground stations—in Jinan, Hefei, Nanshan, Wuhan, Beijing, and Shanghai—as well as with a station in Stellenbosch, South Africa. The satellite transmitted approximately 250 million quantum photons per second. During each satellite pass, the system generated up to 1 Mbits of secure keys. It later demonstrated secure key sharing and encrypted communication between Beijing and Stellenbosch.

This study lays a solid foundation for the deployment of a constellation of quantum microsatellites, provides crucial technical support for large-scale quantum communication networks, and holds promise for the global deployment of the quantum internet.

A Nature reviewer praised it as "a technically impressive accomplishment," marking "considerable progress towards trusted-node constellations for widespread satellite QKD services." The reviewer also noted that "it demonstrates the maturity of satellite QKD technology and represents a milestone for the realization of a satellite constellation for quantum and classical communication."

Journal

Nature

DOI

10.1038/s41586-025-08739-z

Article Title

Microsatellite-based real-time quantum key distribution

Article Publication Date

19-Mar-2025

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