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Quantum-Secure Ballots Demonstrated in the Lab

Quantum bits (qubits) enable these conditions. The quantum voting protocol involves creating a quantum state of many quantum-entangled qubits known as a Greenberger-Horne-Zeilinger (GHZ) state, with one qubit for each voter. The state can be prepared so that each qubit measurement randomly produces 0 or 1, but the entanglement guarantees that the total number of 1s is either even or odd. These states can be prepared using, for example, photons as qubits, with 0 and 1 corresponding to distinct polarization states.

Such a protocol was proposed in 2022 by quantum information theorist Federico Centrone of the Barcelona Institute of Science and Technology in Spain and his co-workers [3]. Implementing it requires that the voters be able to verify that they have been given a true GHZ state and not some other state that subverts the protocol. Such verifications can be carried out, but each qubit can only be used once—either for voting or for verification. So extra sets of GHZ states must be produced for multiple rounds of verification.

Two research teams have now demonstrated the fundamental features of the protocol using photons as qubits, although several practical challenges remain before it can be used in a real election. Joey Marcellino, a PhD student at the University of Geneva, and his co-workers randomly assign each round as either a verification or a voting round [1]. Meanwhile, Laurent-Puig and his colleagues (including Centrone) simply chose to postpone the verification aspect of the protocol for future work [2].

Laser spectroscopy helps reveal hidden nuclear properties in fermium

For the first time, researchers have determined the shape of the actinide nucleus of fermium-255 and measured its structure with high precision and resolution.

This breakthrough, published in Physical Review Letters, supports modern theoretical models and opens new possibilities for understanding the behavior of the heaviest atomic nuclei.

Studying the shapes of atomic nuclei provides essential insights into their internal structure. In very heavy nuclides, nuclear shape is closely linked to their stability against spontaneous fission and is therefore a key factor in the search for longer-lived superheavy elements. Spontaneous fission arises from the strong repulsion between the many protons in heavy nuclei and ultimately limits the existence of elements beyond uranium (element 92).

Tiny floating magnet detects ultrafaint magnetic fields at room temperature

Measuring faint magnetic fields is useful in a number of areas, including mapping brain activity, monitoring hearts and probing fundamental physics. Typically, picking up such weak signals requires expensive or bulky equipment, such as liquid-helium cooling tanks or specially shielded rooms that block out Earth’s magnetic field.

In a paper published in the journal Science, researchers report creating a miniature floating magnet that detects these faint signals at room temperature.

To build their magnetometer, the team suspended a tiny permanent magnetic disk, smaller than a grain of rice, inside a glass vacuum chamber, where it levitated in midair. An overhead stack of magnets pulled the disk upward against gravity, while a graphite plate beneath it provided a repulsive force to help stabilize it.

Boron layers could set a superconductivity record, theoretical study predicts

Scientists in China predict that stacking two microscopic layers of boron could set a new record for superconductivity. Superconductors are materials that conduct electricity with zero resistance. Traditional types need temperatures close to absolute zero to work, requiring complex and expensive cooling equipment.

However, in this new research published in the journal Physical Review Letters, the team predicted a single-element superconductor that works at a much less extreme temperature. If replicated in the real world, it could mean much lower cooling costs and a major step toward improving the efficiency of power grids and technologies like medical MRI scanners and maglev trains.

Currently, the best-known elemental superconductor, scandium, reaches 36 Kelvin (K) (−237°C [-395°F]) only at about 260 gigapascals of pressure. In the new study, scientists predict a threshold of 68 K (−205°C [-337°F]) for the stacked boron layers.

Physicists watch a material’s electrons assemble, and reassemble, into coexisting phases

A tall glass of ice water isn’t just a thirst quencher; it’s also an everyday example of coexisting phases. Water can exist simultaneously in both liquid and solid phases. As it turns out, this phase duality can also exist in more exotic quantum materials, in ways that are far more complicated to tease apart.

A new study by MIT physicists sheds light on how two different phases of electron behavior can emerge and coexist in the same quantum material.

Their results, reported in the journal Nature Physics, can help explain how some materials host superconductivity, magnetism and other electronic phases. Untangling such phases and understanding how they emerge will help engineers control electronic behavior and design high-performance quantum devices.

XENONnT detector narrows the hunt for dark matter

Using a detector filled with nearly 9 metric tons of liquid xenon, researchers have delivered some of the most sensitive dark matter results ever recorded. In the latest analysis from the XENON collaboration, working at the Gran Sasso National Laboratory in Italy, researchers carried out a “blind” test to avoid bias in measurements of the XENONnT detector, pushing the experiment’s sensitivity to unprecedented levels.

Their results have been published in Physical Review Letters and could now tighten the net around several of the leading candidates for the true nature of dark matter.

Galactic spins carry fingerprints of the primordial universe

The origin of spin in spiral and elliptical galaxies has posed a long-standing puzzle for astronomers. One idea, known as tidal torque theory, proposes that galaxies’ spins are an imprinted record of the early universe, imparted by gravity long before galaxies first formed and still detectable in galaxies today.

Through new research published in Nature Astronomy, a team led by Ming-Jie Sheng at Xiamen University has put that idea to its toughest test yet.

Crossing into a mirror world: Particles turn to wisps of fog, and the magnetic monopole paradox dissolves

In Goethe’s ballad “Erlkönig,” immortalized in Schubert’s fevered 1815 setting, a dying boy riding through the night sees a spectral king beckoning from the darkness. His father calms him: “Mein Sohn, es ist ein Nebelstreif”—my son, it is only a wisp of fog. In the poem, the father’s reassurance proves tragically wrong. In the quantum world, however, his words acquire an uncanny new meaning.

For four decades, physicists have been haunted by their own apparition: a particle that scatters off a magnetic monopole and seems to vanish from the theory entirely, its outgoing state missing from the books. A team of physicists from Ghent University, the University of Cambridge and the University of Oxford now shows, in a paper published in Nature Physics, where such particles go.

Throwing quantum wave packets at a so-called “duality defect”—an interface stitching together two quantum worlds that are secretly descriptions of the same physics—they find that the particle is never reflected: it always passes through, with 100% probability, and reemerges as precisely what the father promised. A wisp of fog: faint, smeared out, trailing an invisible thread of quantum mist back to the mirror’s edge.

New ‘shape-shifting’ architecture brings versatility to photonic quantum computing

Using light to process quantum information is one of the most promising approaches to building future quantum computers. Light particles, known as photons, are excellent carriers of quantum information, but their lack of natural interactions has created a major challenge for researchers seeking to build systems capable of performing a full range of computations.

Now, researchers from Imperial’s Department of Physics and external collaborators have developed a new architecture, called Clavina, that overcomes this longstanding limitation.

Published in Nature Photonics, the study demonstrates a programmable platform that combines both linear and nonlinear quantum operations within a single system, expanding the capabilities of quantum computers that use light.

Just 50°C decides whether an ultrathin magnetic film stays flat or falls apart

Magnetic storage technologies, which store information in the direction of magnetization, play an essential role in modern data storage. Hard disk drives (HDDs) are widely used for long-term storage, while nonvolatile magnetic random-access memory (MRAM) is emerging as a promising alternative to flash memory.

These devices rely on epitaxial ultrathin magnetic alloy films in which two atomic species are arranged in alternating layers along a single crystallographic direction. This structure creates a large magnetocrystalline anisotropy energy (MAE), making the magnetic state more stable and preventing stored bits from accidentally flipping.

The more perfectly ordered the atomic arrangement—measured by the degree of L10 ordering—the greater the MAE and thermal stability of each magnetic bit.

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