Quantum error correction codes protect quantum information from decoherence and quantum noise, and are therefore crucial to the development of quantum computing and the creation of more reliable and complex quantum algorithms. One example is the five-qubit error correction code, five being the minimum number of qubits required to fix single-qubit errors. These contain five physical qubits (a basic off/on unit of quantum information made using trapped ions, superconducting circuits, or quantum dots) to correct one logical qubit (a collection of physical qubits arranged in such a way as to correct errors). Yet imperfections in the hardware can still lead to quantum errors.

A method of testing quantum error correction codes is self-testing. Self-testing is a powerful tool for verifying quantum properties using only input-output statistics, treating quantum devices as black boxes. It has evolved from bipartite systems consisting of two quantum subsystems, to multipartite entanglement, where entanglement is among three or more subsystems, and now to genuinely entangled subspaces, where every state is fully entangled across all subsystems. Genuinely entangled subspaces offer stronger, guaranteed entanglement than general multipartite states, making them more reliable for quantum computing and error correction.

In this research, self-testing techniques are used to certify genuinely entangled logical subspaces within the five-qubit code on photonic and superconducting platforms. This is achieved by preparing informationally complete logical states that span the entire logical space, meaning the set is rich enough to fully characterize the behaviour of the system. They deliberately introduce basic quantum errors by simulating Pauli errors on the physical qubit, which mimics real-world noise. Finally, they use mathematical tests known as Bell inequalities, adapted to the framework used in quantum error correction, to check whether the system evolves in the initial logical subspaces after the errors are introduced.

Extractability measures tell you how close the tested quantum system is to the ideal target state, with 1 being a perfect match. The certification is supported by extractability measures of at least 0.828 ± 0.006 and 0.621 ± 0.007 for the photonic and superconducting systems, respectively. The photonic platform achieved a high extractability score, meaning the logical subspace was very close to the ideal one. The superconducting platform had a lower score but still showed meaningful entanglement. These scores show that the self-testing method works in practice and confirm strong entanglement in the five-qubit code on both platforms.

This research contributes to the advancement of quantum technologies by providing robust methods for verifying and characterizing complex quantum structures, which is essential for the development of reliable and scalable quantum systems. It also demonstrates that device-independent certification can extend beyond quantum states and measurements to more general quantum structures.

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Quantum error correction for beginners by Simon J Devitt, William J Munro and Kae Nemoto (2013)

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For almost a century, physicists have tried to understand why and how materials become magnetic. From refrigerator magnets to magnetic memories, the microscopic origins of magnetism remain a surprisingly subtle puzzle — especially in materials where electrons behave both like individual particles and like a collective sea.

In most transition-metal compounds, magnetism comes from the dance between localized and mobile electrons. Some electrons stay near their home atoms and form tiny magnetic moments (spins), while others roam freely through the crystal. The interaction between these two types of electrons produces “double-exchange” ferromagnetism — the mechanism that gives rise to the rich magnetic behaviour of materials such as manganites, famous for their colossal magnetoresistance (a dramatic change in electrical resistance under a magnetic field). Traditionally, scientists modelled this behaviour by treating the localized spins as classical arrows — big and well-defined, like compass needles. This approximation works well enough for explaining basic ferromagnetism, but experiments over the last few decades have revealed strange features that defy the classical picture. In particular, neutron scattering studies of manganites showed that the collective spin excitations, called magnons, do not behave as expected. Their energy spectrum “softens” (the waves slow down) and their sharp signals blur into fuzzy continua — a sign that the magnons are losing their coherence. Until now, these effects were usually blamed on vibrations of the atomic lattice (phonons) or on complex interactions between charge, spin, and orbital motion.

A new theoretical study challenges that assumption. By going fully quantum mechanical — treating every localized spin not as a classical arrow but as a true quantum object that can fluctuate, entangle, and superpose — the researchers have reproduced these puzzling experimental observations without invoking phonons at all. Using two powerful model systems (a quantum version of the Kondo lattice and a two-orbital Hubbard model), the team simulated how electrons and spins interact when no semiclassical approximations are allowed. The results reveal a subtle quantum landscape. Instead of a single type of electron excitation, the system hosts two. One behaves like a spinless fermion — a charge carrier stripped of its magnetic identity. The other forms a broad, “incoherent” band of excitations arising from local quantum triplets. These incoherent states sit close to the Fermi level and act as a noisy background — a Stoner-like continuum — that the magnons can scatter off. The result: magnons lose their coherence and energy in just the way experiments observe.

Perhaps most surprisingly, this mechanism doesn’t rely on the crystal lattice at all. It’s an intrinsic consequence of the quantum nature of the spins themselves. Larger localized spins, such as those in classical manganites, tend to suppress the effect — explaining why decoherence is weaker in some materials than others. Consequently, the implications reach beyond manganites. Similar quantum interplay may occur in iron-based superconductors, ruthenates, and heavy-fermion systems where magnetism and superconductivity coexist. Even in materials without permanent local moments, strong electronic correlations can generate the same kind of quantum magnetism.

In short, this work uncovers a purely electronic route to complex magnetic dynamics — showing that the quantum personality of the electron alone can mimic effects once thought to require lattice distortions. By uniting electronic structure and spin excitations under a single, fully quantum description, it moves us one step closer to understanding how magnetism truly works in the most intricate materials.

Do you want to learn more about this topic?

Nanoscale electrodynamics of strongly correlated quantum materials by Mengkun Liu, Aaron J Sternbach and D N Basov (2017)

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House of Lords committee urges government to stem exodus of science and technology companies

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The White House said Nov. 4 it is renominating Jared Isaacman to be NASA administrator, the latest twist in an unprecedented saga over the agency’s leadership.

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Telesat is preparing to deploy a couple of Lightspeed pathfinders in December 2026, with 96 satellites for an initial global broadband service from LEO set to launch the following year to offset mounting geostationary business declines.

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An Ariane 6 successfully launched a radar imaging satellite Nov. 4 after European agencies chose to use a larger rocket to ensure an earlier launch.

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Scientists fear merger of Department of Energy advisory committees that gave them their voices at agency

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A 14th-century teenager died from the Black Death in Edinburgh. Learn how researchers discovered the pathogen in his teeth, and how this may be the first scientific evidence of the plague in the city.

London — Warsaw Increasing tensions with Russia have prompted defense spending boosts throughout Europe that will benefit fledgling smallsat launcher companies across the continent.  But Europe is still years away from meeting its own space access needs, analysts said.  The progress of European smallsat launcher developers has been slower than promised, with companies facing technical […]

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SES has turned to Japan’s flagship operator for extra satellite bandwidth to keep up with soaring connectivity demand from passengers flying across Asia, even after significantly expanding its own fleet by buying Intelsat.

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Chemical analysis could help predict locations of other ancient sites with impeccable fossils

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Learn how chemists were studying a known antibiotic when they discovered a molecule 100 times more potent at defeating drug-resistant superbugs.

Sovereign Control and Precision Intelligence Set to Lead Global Priorities Paris, France [October, 2025] – Novaspace’s 18th edition of the Earth Observation Data and Services Market report signals a decisive […]

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From the first satellite in orbit, to the first human in space, to the first steps on the moon, the United States government has always framed space exploration as a race. As U.S.-China space competition intensifies, so too does our American instinct to reach the next first. The Earth-moon Lagrange points may be next. In […]

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Intuitive Machines, a lunar lander company, announced Nov. 4 it is buying Lanteris Space Systems, a satellite builder formerly known as Maxar.

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Learn about the closest black hole from Earth, Gaia BH1. This recently discovered black hole is dormant, but it’s only 1,600 light-years away.

For the first time, there’s a special prize for a research-themed dance generated by an artificial intelligence program

Using a new type of low-power, compact, fluid-based prism to steer the beam in a laser scanning microscope could transform brain imaging and help researchers learn more about neurological conditions such as Alzheimer’s disease.

The “electrowetting prism” utilized was developed by a team led by Juliet Gopinath from the electrical, computer and energy engineering and physics departments at the University of Colorado at Boulder (CU Boulder) and Victor Bright from CU Boulder’s mechanical engineering department, as part of their ongoing collaboration on electrically controllable optical elements for improving microscopy techniques.

“We quickly became interested in biological imaging, and work with a neuroscience group at University of Colorado Denver Anschutz Medical Campus that uses mouse models to study neuroscience,” Gopinath tells Physics World. “Neuroscience is not well understood, as illustrated by the neurodegenerative diseases that don’t have good cures. So a great benefit of this technology is the potential to study, detect and treat neurodegenerative diseases such as Alzheimer’s, Parkinson’s and schizophrenia,” she explains.

The researchers fabricated their patented electrowetting prism using custom deposition and lithography methods. The device consists of two immiscible liquids housed in a 5 mm tall, 4 mm diameter glass tube, with a dielectric layer on the inner wall coating four independent electrodes. When an electric field is produced by applying a potential difference between a pair of electrodes on opposite sides of the tube, it changes the surface tension and therefore the curvature of the meniscus between the two liquids. Light passing through the device is refracted by a different amount depending on the angle of tilt of the meniscus (as well as on the optical properties of the liquids chosen), enabling beams to be steered by changing the voltage on the electrodes.

Beam steering for scanning in imaging and microscopy can be achieved via several means, including mechanically controlled mirrors, glass prisms or acousto-optic deflectors (in which a sound wave is used to diffract the light beam). But, unlike the new electrowetting prisms, these methods consume too much power and are not small or lightweight enough to be used for miniature microscopy of neural activity in the brains of living animals.

In tests detailed in Optics Express, the researchers integrated their electrowetting prism into an existing two-photon laser scanning microscope and successfully imaged individual 5 µm-diameter fluorescent polystyrene beads, as well as large clusters of those beads.

They also used computer simulation to study how the liquid–liquid interface moved, and found that when a sinusoidal voltage is used for actuation, at 25 and 75 Hz, standing wave resonance modes occur at the meniscus – a result closely matched by a subsequent experiment that showed resonances at 24 and 72 Hz. These resonance modes are important for enhancing device performance since they increase the angle through which the meniscus can tilt and thus enable optical beams to be steered through a greater range of angles, which helps minimize distortions when raster scanning in two dimensions.

Bright explains that this research built on previous work in which an electrowetting prism was used in a benchtop microscope to image a mouse brain. He cites seeing the individual neurons as a standout moment that, coupled with the current results, shows their prism is now “proven and ready to go”.

Gopinath and Bright caution that “more work is needed to allow human brain scans, such as limiting voltage requirements, allowing the device to operate at safe voltage levels, and miniaturization of the device to allow faster scan speeds and acquiring images at a much faster rate”. But they add that miniaturization would also make the device useful for endoscopy, robotics, chip-scale atomic clocks and space-based communication between satellites.

The team has already begun investigating two other potential applications: LiDAR (light detection and ranging) systems and optical coherence tomography (OCT). Next, the researchers “hope to integrate the device into a miniaturized microscope to allow imaging of the brain in freely moving animals in natural outside environments,” they say. “We also aim to improve the packaging of our devices so they can be integrated into many other imaging systems.”

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Through missions currently on the books for the Japan Space Agency JAXA, the U.S. Space Force, European Space Agency, UK Space Agency and Eutelsat OneWeb, the Tokyo-based on-orbit servicing company Astroscale aims to demonstrate inspection and proximity operations, rendezvous and docking, debris removal and refueling. When Astroscale was founded in 2013, the business was focused […]

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