As quantum computers threaten traditional encryption, researchers are developing quantum networks to enable ultra-secure communication.
Scientists at Leibniz University Hannover have pioneered a new method using light frequencies to enhance quantum key distribution. This breakthrough reduces complexity, cuts costs, and paves the way for scalable, tap-proof quantum internet infrastructure.
Physicists have performed a groundbreaking simulation they say sheds new light on an elusive phenomenon that could determine the ultimate fate of the Universe.
Pioneering research in quantum field theory around 50 years ago proposed that the universe may be trapped in a false vacuum – meaning it appears stable but in fact could be on the verge of transitioning to an even more stable, true vacuum state. While this process could trigger a catastrophic change in the Universe’s structure, experts agree that predicting the timeline is challenging, but it is likely to occur over an astronomically long period, potentially spanning millions of years.
In an international collaboration between three research institutions, the team report gaining valuable insights into false vacuum decay – a process linked to the origins of the cosmos and the behaviour of particles at the smallest scales. The collaboration was led by Professor Zlatko Papic, from the University of Leeds, and Dr Jaka Vodeb, from the Jülich Supercomputing Centre (JSC) at Forschungszentrum Jülich, Germany.
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Imagine a world where thoughts aren’t confined to the brain, but instantly shared across a vast network of neurons, transcending the limits of space and time. This isn’t science fiction, but a possibility hinted at by one of the most puzzling aspects of quantum physics: entanglement.
Quantum entanglement, famously dubbed spooky action at a distance by Einstein, describes a phenomenon where two or more particles become intrinsically linked. They share a quantum state, no matter how far apart they are. Change one entangled particle, and its partner instantly reacts, even across vast distances.
This property, which troubled Einstein, has been repeatedly confirmed through experiments, notably by physicist John Clauser and his colleagues, who received the 2022 Nobel Prize in Physics for their groundbreaking work on quantum entanglement.
To address this challenge, the researchers propose two alternative QV tests that sidestep classical simulation entirely. Their primary modification involves using parity-preserving quantum gates — gates that maintain the parity (even or odd sum) of qubits throughout the computation. This allows the heavy output subspace to be known in advance, eliminating the need for classical verification.
The first approach, the parity-preserving benchmark, modifies the structure of the quantum circuits while keeping the number of two-qubit interactions the same. The researchers argue that this change has minimal impact on experimental implementation but significantly reduces computational costs.
“Since the interaction part is unaffected, the number of fundamental two-qubit gates, 3 in case of CNOTs, remains unchanged,” they write in the paper.
Our entire reality could – in theory – be built on a bed of sand, teetering on the brink of collapse. If so, a new device developed by a collaboration of physicists in Europe might give us some idea of how it all ends.
Using a process known as quantum annealing, the researchers have provided a proof-of-concept method to study the dynamics of a terrifying kind of reality-decay that would pull at the threads of physics, causing them to unravel.
Were such an event to occur somewhere in the cosmos, the quantum laws that lend structure to matter would be rewritten at the speed of light, spelling an end to all reality as we know it.
A research team from the University of Science and Technology of China has demonstrated the ability to electrically manipulate the spin filling sequence in a bilayer graphene (BLG) quantum dot (QD). This achievement, published in Physical Review Letters, showcases the potential to control the spin degree of freedom in BLG, a material with promising applications in quantum computing and advanced electronics.
BLG has drawn extensive attention in recent years due to its unique properties. When an out-of-plane electric field is applied, it can generate a tunable band gap. Moreover, the trigonal warping effect, caused by the skew interlayer coupling, gives rise to additional minivalley degeneracy, greatly influencing the behavior of charge carriers. Quantum dot devices, which can precisely control the number of charge carriers, have become a crucial tool for studying these phenomena at the single-particle level.
The research team delved into the intricate dynamics of electron shell structures within bilayer graphene quantum dot, focusing on how these structures can be manipulated through the trigonal warping effect, a unique feature of bilayer graphene. They employed a highly tunable quantum dot device, which provided the means to control the electron filling sequence. They began by applying a small perpendicular electric field, observing that the s-shell filled with four electrons, two with spin-up and two with spin-down, each from opposite valleys.
From high-speed communication to quantum computing and sensing, the detection, transmission, and manipulation of light (photons) have transformed modern electronics. Central to these systems are photon detectors, which detect and measure photons.
One notable type is the superconducting nanowire single-photon detector (SNSPD). SNSPDs utilize ultra-thin superconducting wires that quickly transition from a superconducting state to a resistive state when a photon strikes, allowing for ultra-fast detection.
The wires in these detectors are arranged in a Peano arced-fractal pattern, which remains consistent across various scales. This unique design enables the detector to detect photons regardless of their direction or polarization (the orientation of the photon’s electric field). Due to these advantages, arced-fractal SNSPDs (AF SNSPDs) are crucial in applications such as light detection and ranging, quantum computing, and quantum communication.
What if time is not as fixed as we thought? Imagine that instead of flowing in one direction—from past to future—time could flow forward or backwards due to processes taking place at the quantum level. This is the thought-provoking discovery made by researchers at the University of Surrey, as a new study reveals that opposing arrows of time can theoretically emerge from certain quantum systems.
For centuries, scientists have puzzled over the arrow of time—the idea that time flows irreversibly from past to future. While this seems obvious in our experienced reality, the underlying laws of physics do not inherently favor a single direction. Whether time moves forward or backwards, the equations remain the same.
Dr. Andrea Rocco, Associate Professor in Physics and Mathematical Biology at the University of Surrey and lead author of the study, said, One way to explain this is when you look at a process like spilled milk spreading across a table, it’s clear that time is moving forward. But if you were to play that in reverse, like a movie, you’d immediately know something was wrong—it would be hard to believe milk could just gather back into a glass.