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Category: quantum physics – Page 48

Quantum key distribution enables secure communication via hybrid and mobile channels

As part of the QuNET project, researchers have demonstrated how quantum key distribution works reliably via hybrid and mobile channels. The results are milestones for sovereign, quantum-secured communication in Germany and have been published in the New Journal of Physics.

Quantum communication is considered a crucial technology for long-term data security and thus also for technological sovereignty in Germany and Europe. At its core is the distribution of secure cryptographic keys based on quantum physical processes—quantum key distribution (QKD).

QKD will not only be important for highly secure communication in government agencies, the military, and businesses, but will also help protect the data we use in our daily lives.

Defining work and heat in quantum systems: Laser light coherence offers a consistent approach

Researchers at the University of Basel have developed a new approach to applying thermodynamics to microscopic quantum systems.

In 1798, the officer and physicist Benjamin Thompson (a.k.a. Count Rumford) observed the drilling of cannon barrels in Munich and concluded that heat is not a substance but can be created in unlimited amounts by mechanical friction.

Rumford determined the amount of heat generated by immersing the cannon barrels in water and measuring how long it took the water to reach boiling. Based on such experiments, thermodynamics was developed in the 19th century. Initially, it was at the service of the Industrial Revolution and explained, physically, for instance, how heat can be efficiently converted into useful work in steam engines.

Innovation in Homeland Security Lives Between Sectors

#homelandsecurity #innovation

Having been involved in the creation of the Department of Homeland Security’s Science & Technology Directorate, and with decades of experience working at the intersection of government, industry, and academia, I have come to a simple but important observation: innovation in homeland security doesn’t happen in one area. Instead, it thrives where mission, research, and engineering come together.

Convergence is the catalyst. Cyber defense, autonomous systems, identity management, quantum computing, and photonics are all examples of technological advancements that didn’t develop in isolation. Their progress was the result of different sectors working together on shared goals, risk management, and practical use. Homeland security enterprise is constituted by a multi-sectoral nature: government sets mission needs, industry creates scalable solutions, and academia provides the necessary research. Real innovation happens when these areas come together.

Statistical data highlights the significance of this alignment. Research on cyber-behavior, for instance, demonstrates that organizational culture, national context, and employee backgrounds significantly impact risk outcomes. Practically speaking, this implies that secure systems cannot be developed in isolation. The human and institutional context is as crucial as technical advancements.

Rules that Reality Plays By — Dr. Stephen Wolfram, DemystifySci #343

Stephen Wolfram is a physicist, mathematician, and programmer who believes he has discovered the computational rules that organize the universe at the finest grain. These rules are not physical rules like the equations of state or Maxwell’s equations. According to Wolfram, these are rules that govern how the universe evolves and operates at a level at least one step down below the reality that we inhabit. His computational principles are inspired by the results observed in cellular automata systems, which show that it’s possible to take a very simple system, with very simple rules, and end up at complex patterns that often look organic and always look far more intricate than the black and white squares that the game started with. He believes that the hyperspace relationships that emerge when he applies a computational rule over and over again represent the nature of the universe — and that the relationships that emerge contain everything from the seed of human experience to the equations for relativity, evolution, and black holes. We sit down with him for a conversation about the platonic endeavor that he has undertaken, where to draw the line between lived experience and the computational universe, the limits of physics, and the value of purpose and the source of consciousness.

MAKE HISTORY WITH US THIS SUMMER:
https://demystifysci.com/demysticon-2025

PATREON
/ demystifysci.

PARADIGM DRIFT
https://demystifysci.com/paradigm-drift-show.

Material solutions to quantum spookiness: https://www.youtube.com/@MaterialAtomics.

00:00 Go!

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Quantum photonic chip integrates light-emitting molecules with single-mode waveguides

Photonic quantum processors, devices that can process information leveraging quantum mechanical effects and particles of light (photons), have shown promise for numerous applications, ranging from computations and communications to the simulation of complex quantum systems.

To be deployed in real-world settings, however, these photonic chips should reliably integrate many deterministic and indistinguishable single-photon sources on a single chip.

So far, achieving this has proved highly challenging. Most such photonic quantum chips developed so far utilize solid-state single-photon emitters that are limited by so-called spectral diffusion (i.e., the random “wandering” of their emission frequency).

Light is born from the vacuum: laser modeling confirms a quantum physics prediction

Physicists from Oxford and Lisbon have run a full 3D, time-resolved simulation showing that empty space can act like a nonlinear medium. Their model finds that three intense laser pulses make photons rebound and forge a fourth beam, echoing a long-standing prediction from quantum electrodynamics.

Classical physics treats vacuum as an absence. Quantum theory disagrees. The vacuum teems with flickering pairs of virtual electrons and positrons that borrow energy briefly and vanish. Strong electromagnetic fields can polarize those pairs. That tiny response turns “nothing” into a medium with a faint optical nonlinearity.

When three high-power laser pulses cross at the right angles and frequencies, quantum electrodynamics (QED) predicts four-wave mixing in vacuum. The combined fields nudge virtual pairs, which then mediate photon‑photon scattering. A new, phase‑matched beam should appear with a frequency and direction dictated by the input pulses.

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