In this episode of Physics World Stories, theoretical physicist, cosmologist and author Paul Davies discusses his latest book, Quantum 2.0: The Past, Present, and Future of Quantum Physics. A Regents Professor at Arizona State University, Davies reflects on how the first quantum revolution transformed our understanding of nature – and what the next one might bring.
He explores how emerging quantum technologies are beginning to merge with artificial intelligence, raising new ethical and philosophical questions. Could quantum AI help tackle climate change or tackle issues like hunger? And how far should we go in outsourcing planetary management to machines that may well prioritize their own survival?
Davies also turns his gaze to the arts, imagining a future where quantum ideas inspire music, theatre and performance. From jazz improvized by quantum algorithms to plays whose endings depend on quantum outcomes, creativity itself could enter a new superposition.
Hosted by Andrew Glester, this episode blends cutting-edge science and imagination in trademark Paul Davies style.
Photodetectors convert light into electrical signals and are essential in technologies ranging from consumer electronics and communications to healthcare. They also play a vital role in scientific research. Researchers are continually working to improve their sensitivity, response speed, spectral range, and design efficiency.
Since the discovery of graphene’s remarkable electrical properties, there has been growing interest in using graphene and other two-dimensional (2D) materials to advance photodetection technologies. When light interacts with these materials, it excites electrons that must travel to a nearby contact electrode to generate an electrical signal. The ease with which this occurs depends on the work functions of the materials involved, specifically, the difference between them, known as the Schottky barrier height. Selecting an optimal combination of 2D material and electrode can minimize this barrier, enhancing the photodetector’s sensitivity and speed. Unfortunately, traditional electrode materials have fixed work functions which are limiting 2D photodetector technology.
PEDOT:PSS is a widely used electrode material in photodetectors due to its low cost, flexibility, and transparency. In this study, the researchers have developed PEDOT:PSS electrodes with tunable work functions ranging from 5.1 to 3.2 eV, making them compatible with a variety of 2D materials and ideal for optimizing device performance in metal-semiconductor-metal architectures. In addition, their thorough investigation demonstrates that the produced photodetectors performed excellently, with a significant forward current flow (rectification ratio ~10⁵), a strong conversion of light to electrical output (responsivity up to 1.8 A/W), and an exceptionally high Ilight/Idark ratio of 10⁸. Furthermore, the detectors were highly sensitive with low noise, had very fast response times (as fast as 3.2 μs), and thanks to the transparency of PEDOT:PSS, showed extended sensitivity into the near-infrared region.
This study demonstrates a tunable, transparent polymer electrode that enhances the performance and versatility of 2D photodetectors, offering a promising path toward flexible, self-powered, and wearable optoelectronic systems, and paving the way for next-generation intelligent interactive technologies.
Quantum Conference Key Agreement (QCKA) is a cryptographic method that allows multiple parties to establish a shared secret key using quantum technology. This key can then be used for secure communication among the parties.
Unlike traditional methods that rely on classical cryptographic techniques, QCKA leverages the principles of quantum mechanics, particularly multipartite entanglement, to ensure security.
A key aspect of QCKA is creating and distributing entangled quantum states among the parties. These entangled states have unique properties that make it impossible for an eavesdropper to intercept the key without being detected.
Researchers measure the efficiency and performance of the key agreement protocol using a metric known as the key rate.
One problem with state-of-the-art QCKA schemes is that this key rate decreases exponentially with the number of users.
Previous solutions to this problem, based on single-photon interference, have come at the cost of requiring global phase locking. This makes them impractical to put in place experimentally.
However, the authors of this new study have been able to circumvent this requirement, by adopting an asynchronous pairing strategy. Put simply, this means that measurements taken by different parties in different places do not need to happen at exactly at the same time.
Their solution effectively removes the need for global phase locking while still maintaining the favourable scaling of the key rate as in other protocols based on single-photon interference.
The new scheme represents an important step towards realising QCKA at long distances by allowing for much more practical experimental configurations.
Schematic representation of quantum group network via circular asynchronous interference (Courtesy: Hua-Lei Yin)
Schools in the US are installing vape-detection tech in bathrooms to thwart student nicotine and cannabis use. A new investigation reveals the impact of using spying to solve a problem.
A U.S. government official warned that a draft European space law could “stifle innovation,” as other countries also assess the potential impacts of the proposed legislation.
European government officials stressed the need to build strong, autonomous space capabilities, even as the continent continues to rely on foreign companies for some launches.
Eutelsat is a step closer to the financing needed to refresh its OneWeb LEO broadband constellation, after the French operator’s board approved plans Nov. 18 to raise nearly $1 billion from anchor shareholders.
Learn how researchers traced chemical evidence of early life in ancient rocks and found signs of photosynthesis nearly a billion years earlier than expected.
Scientists have collected ancient RNA from mammoth samples up to 52,000 years old. Learn how they can use that RNA to indicate what happened to the mammoth as it took its last breaths.
Learn more about how scientists uncovered an unlikely community of arachnids in Europe’s Sulfur Cave and why these spiders usually don’t live together.
As someone deeply involved in the space sector, I’ve seen firsthand how low Earth orbit (LEO) is becoming increasingly congested. Satellite operators, space agencies and aerospace companies are all facing a growing threat from orbital debris. With more than 10,000 active satellites already in orbit and millions of smaller fragments accumulating, the risk of collision […]
Coherent crystalline interfaces Atomic-resolution image of a superconducting germanium:gallium (Ge:Ga) trilayer with alternating Ge:Ga and silicon layers demonstrating precise control of atomic interfaces. (Courtesy: Salva Salmani-Rezaie)
The ability to induce superconductivity in materials that are inherently semiconducting has been a longstanding research goal. Improving the conductivity of semiconductor materials could help develop quantum technologies with a high speed and energy efficiency, including superconducting quantum bits (qubits) and cryogenic CMOS control circuitry. However, this task has proved challenging in traditional semiconductors – such as silicon or germanium – as it is difficult to maintain the optimal superconductive atomic structure.
In a new study, published in Nature Nanotechnology, researchers have used molecular beam epitaxy (MBE) to grow gallium-hyperdoped germanium films that retain their superconductivity. When asked about the motivation for this latest work, Peter Jacobson from the University of Queensland tells Physics World about his collaboration with Javad Shabani from New York University.
“I had been working on superconducting circuits when I met Javad and discovered the new materials their team was making,” he explains. “We are all trying to understand how to control materials and tune interfaces in ways that could improve quantum devices.”
Germanium: from semiconductor to superconductor
Germanium is a group IV element, so its properties bridge those of both metals and insulators. Superconductivity can be induced in germanium by manipulating its atomic structure to introduce more electrons into the atomic lattice. These extra electrons interact with the germanium lattice to create electron pairs that move without resistance, or in other words, they become superconducting.
Hyperdoping germanium (at concentrations well above the solid solubility limit) with gallium induces a superconducting state. However, this material is traditionally unstable due to the presence of structural defects, dopant clustering and poor thickness control. There have also been many questions raised as to whether these materials are intrinsically superconducting, or whether it is actually gallium clusters and unintended phases that are solely responsible for the superconductivity of gallium-doped germanium.
Considering these issues and looking for a potential new approach, Jacobson notes that X-ray absorption measurements at the Australian Synchrotron were “the first real sign” that Shabani’s team had grown something special. “The gallium signal was exceptionally clean, and early modelling showed that the data lined up almost perfectly with a purely substitutional picture,” he explains. “That was a genuine surprise. Once we confirmed and extended those results, it became clear that we could probe the mechanism of superconductivity in these films without the usual complications from disorder or spurious phases.”
Epitaxial growth improves superconductivity control
In a new approach, Jacobson, Shabani and colleagues used MBE to grow the crystals instead of relying on ion implantation techniques, allowing the germanium to by hyperdoped with gallium. Using MBE forces the gallium atoms to replace germanium atoms within the crystal lattice at levels much higher than previously seen. The process also provided better control over parasitic heating during film growth, allowing the researchers to achieve the structural precision required to understand and control the superconductivity of these germanium:gallium (Ge:Ga) materials, which were found to become superconducting at 3.5 K with a carrier concentration of 4.15 × 1021 holes/cm3. The critical gallium dopant threshold to achieve this was 17.9%.
Using synchrotron-based X-ray absorption, the team found that the gallium dopants were substitutionally incorporated into the germanium lattice and induced a tetragonal distortion to the unit cell. Density functional theory calculations showed that this causes a shift in the Fermi level into the valence band and flattens electronic bands. This suggests that the structural order of gallium in the germanium lattice creates a narrow band that facilitates superconductivity in germanium, and that this superconductivity arises intrinsically in the germanium, rather than being governed by defects and gallium clusters.
The researchers tested trilayer heterostructures – Ge:Ga/Si/Ge:Ga and Ge:Ga/Ge/Ge:Ga – as proof-of-principle designs for vertical Josephson junction device architectures. In the future, they hope to develop these into fully fledged Josephson junction devices.
Commenting on the team’s future plans for this research, Jacobson concludes: “I’m very keen to examine this material with low-temperature scanning tunnelling microscopy (STM) to directly measure the superconducting gap, because STM adds atomic-scale insights that complement our other measurements and will help clarify what sets hyperdoped germanium apart”.
As shown by the recent SpaceNews editorials by Mustafa Bilal and Stirling Forbes, there is currently much talk of a coming lunar “gold rush,” with nations and companies seemingly in a mad scramble to access the moon for its alleged resources. But how realistic is this vision, and could the pursuit of it do more harm […]
It is book week here at Physics World and over the course of three days we are presenting conversations with the authors of three fascinating and fun books about physics. First up is my Physics World colleague Michael Banks, whose book Physics Around the Clock: Adventures in the Science of Everyday Living starts with your morning coffee and ends with a formula for making your evening television viewing more satisfying.
As well as the rich physics of coffee, we chat about strategies for finding the best parking spot and the efficient boarding of aeroplanes. If you have ever wondered why a runner’s ponytail swings from side-to-side when they reach a certain speed – we have the answer for you.
Other daily mysteries that we explore include how a hard steel razor blade can be dulled by cutting relatively soft hairs and why quasiparticles called “jamitons” are helping physicists understand the spontaneous appearance of traffic jams. And a warning for squeamish listeners, we do talk about the amazing virus-spreading capabilities of a flushing toilet.
This episode is supported by the APS Global Physics Summit, which takes place on 15–20 March, 2026, in Denver, Colorado, and online.
Bangalore, November 18, 2025 — Novaspace, the global consulting and market-intelligence firm dedicated to the space sector, announces the opening of its new office in India, marking a strategic milestone […]