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Category: quantum physics – Page 64

Innsbruck develops new technique to improve multi-photon state generation

Quantum dots – semiconductor nanostructures that can emit single photons on demand – are considered among the most promising sources for photonic quantum computing.

However, every quantum dot is slightly different and may emit a slightly different color, according to a team at the University of Innsbruck, Austria, which has developed a technique to improve multi-photon state generation. The Innsbruck team states that, “the different forms of quantum dot means that, to produce multi-photon states we cannot use multiple quantum dots.”

Usually, researchers use a single quantum dot and multiplex the emission into different spatial and temporal modes, using a fast electro-optic modulator. But a contemporary technological challenge: faster electro-optic modulators are expensive and often require very customized engineering. To add to that, it may not be very efficient, which introduces unwanted losses in the system.

Nature Publishing: https://www.nature.com/articles/s41534-025-01083-0

Security wise: The team’s work combines years of research in quantum optics, semiconductor physics, and photonic engineering to open the door for next-generation quantum computers andunwanted losses in the system.

Communications. Here’s what you need to know. Securities IO: https://www.securities.io/passive-two-photon-quantum-dots-secure-communication

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Researchers Demonstrate QuantumShield-BC Blockchain Framework

Researchers have developed QuantumShield-BC, a blockchain framework designed to resist attacks from quantum computers by integrating post-quantum cryptography (PQC) utilising algorithms such as Dilithium and SPHINCS+, quantum key distribution (QKD), and quantum Byzantine fault tolerance (Q-BFT) leveraging quantum random number generation (QRNG) for unbiased leader selection. The framework was tested on a controlled testbed with up to 100 nodes, demonstrating resistance to simulated quantum attacks and achieving fairness through QRNG-based consensus. An ablation study confirmed the contribution of each quantum component to overall security, although the QKD implementation was simulated and scalability to larger networks requires further investigation.

Microchip Provides Made-to-Order Photons

A 10-µm-wide microchip can generate light with any desired direction, polarization, and intensity, which will be handy for future quantum technologies.

Emerging technologies for quantum computing and cryptography require small components capable of emitting photons whose properties are precisely controlled. Researchers have been developing such components, and now a team has demonstrated a technique that provides control of direction, polarization, and intensity simultaneously [1]. Like previous experiments, the technique uses microscopic structures on a semiconductor surface to convert wave-like surface excitations to light waves. But the new demonstration uses shapes for these structures that allow more precise control over the outgoing light. The team expects the new technique to find wide use in efforts to build quantum technologies in miniature solid-state devices.

Solid-state miniaturization is one of the few realistic routes toward making quantum technologies practical, scalable, and easily manufacturable, says Fei Ding of the University of Southern Denmark. But there are not many good compact photon sources. “The technology really requires a compact and flexible solid-state photon source that gives us full control over how light is emitted—its direction, polarization, and spatial profile,” Ding says. “This is crucial for building scalable quantum and nanophotonic technologies, where single photons are used as the fundamental carriers of information.”

Scientists Discover Strange New Quantum Behavior in Superconducting Material

A research team has provided the first experimental proof that flat electronic bands in a kagome superconductor are active and directly shape electronic and magnetic behaviors.

Researchers from Rice University, working with international partners, have found the first clear evidence of active flat electronic bands within a kagome superconductor. The discovery marks an important step toward creating new strategies for designing quantum materials, including superconductors, topological insulators, and spin-based electronics, which could play a central role in advancing future electronics and computing.

The findings, published on August 14 in Nature Communications.

In our lab we developed a novel nano-thermometer based on a superconducting quantum interference device (tSOT: SQUID on Tip thermometer) with a diameter of less than 50 nanometres that resides at the apex of a sharp pipette

This tool provides scanning cryogenic thermal sensing that is 4 orders of magnitude more sensitive than previous devices allowing the detection of a sub 1 μK temperature difference. Furthermore, it is non-contact and non-invasive and allows thermal imaging of very low intensity, nanoscale energy dissipation down to the fundamental Landauer limit of 40 femtowatts for continuous readout of a single qubit at one gigahertz at 4.2 kelvin.

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