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Dark optical cavity alters superconductivity

An international team of researchers has shown that superconductivity can be modified by coupling a superconductor to a dark electromagnetic cavity. The research opens the door to the control of a material’s properties by modifying its electromagnetic environment.

Electronic structure defines many material properties – and this means that some properties can be changed by applying electromagnetic fields. The destruction of superconductivity by a magnetic field and the use of electric fields to control currents in semiconductors are two familiar examples.

There is growing interest in how electronic properties could be controlled by placing a material in a dark electromagnetic cavity that resonates with an electronic transition in that material. In this scenario, an external field is not applied to the material. Rather, interactions occur via quantum vacuum fluctuations within the cavity.

Holy Grail

“The Holy Grail of cavity materials research is to alter the properties of complex materials by engineering the electromagnetic environment,” explains the team – which includes Itai Keren, Tatiana Webb and Dmitri Basov at Columbia University in the US.

They created an optical cavity from a small slab of hexagonal boron nitride. This was interfaced with a slab of κ-ET, which is an organic low-temperature superconductor. The cavity was designed to resonate with an infrared transition in κ-ET involving the vibrational stretching of carbon–carbon bonds.

Hexagonal boron nitride was chosen because it is a hyperbolic van der Waals material. Van der Waals materials are stacks of atomically-thin layers. Atoms are strongly bound within each layer, but the layers are only weakly bound to each other by the van der Waals force. The gaps between layers can act as waveguides, confining light that bounces back and forth within the slab. As a result the slab behaves like an optical cavity with an isofrequency surface is a hyperboloid in momentum space. Such a cavity supports a large number of modes and vacuum fluctuations, which enhances interactions with the superconductor.

Superfluid suppression

The researchers found that the presence of the cavity caused a strong suppression of superfluid density in κ-ET (a superconductor can be thought of as a superfluid of charged particles). The team mapped the superfluid density using magnetic force microscopy. This involved placing a tiny magnetic tip near to the surface of the superconductor. The magnetic field of the tip cannot penetrate into the superconductor (the Meissner effect) and this results in a force on the tip that is related to the superfluid density. They found that the density dropped by as much as 50% near the cavity interface.

The team also investigated the optical properties of the cavity using scattering-type scanning near-field optical microscope (s-SNOM). This involves firing tightly-focused laser light at an atomic force microscope (AFM) tip that is tapping on the surface of the cavity. The scattered light is processed to reveal the near-field component of light from just the region of the cavity below the tip .

The tapping tip creates phonon polaritons in the cavity, which are particle-like excitations that couple lattice vibrations to light. Analysing the near-field light across the cavity confirmed that the carbon stretching mode of κ-ET is coupled to the cavity. Calculations done by the team suggest that cavity coupling reduces the amplitude of the stretching mode vibrations.

Physicists know that superconductivity can arise as a result of interactions between electrons and phonons (lattice vibrations), So, it is possible that the reduction in superfluid density is related to the suppression of stretching-mode vibrations. However, κ-ET is an unconventional superconductor, which means that physicists do not understand the mechanism that causes superconductivity in the material. Further experiments could therefore shed light on the mysteries of unconventional superconductors.

“We are confident that our experiments will prompt further theoretical pursuits,” the team tells Physics World. The researchers also believe that practical applications could be possible. “Our work shows a new path towards the manipulation of superconducting properties.”

The research is described in Nature.

The post Dark optical cavity alters superconductivity appeared first on Physics World.

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Chernobyl at 40: physics, politics and the nuclear debate today

On 26 April 2026, it will be 40 years since the explosion at Unit 4 of the Chernobyl Nuclear Power Plant – the worst nuclear accident the world has known. In the early hours of 26 April 1986, a badly designed reactor, operated under intense pressure during a safety test, ran out of control. A powerful explosion and prolonged fire followed, releasing radioactive material across Ukraine, Belarus, Russia, with smaller quantities spewing across Europe.

In this episode of Physics World Stories, host Andrew Glester speaks with Jim Smith, an environmental physicist at the University of Portsmouth. Smith began his academic life studying astrophysics, but always had an interest in environmental issues. His PhD in applied mathematics at Liverpool focused on modelling how radioactive material from Chernobyl was transported through the atmosphere and deposited as far away as the Lake District in north-western England.

Smith recounts his visits to the abandoned Chernobyl plant and the 1000-square-mile exclusion zone, now home to roaming wolves and other thriving wildlife. He wants a rational debate about the relative risks, arguing that the accident’s social and economic consequences have significantly outweighed the long-term impacts of radiation itself.

The discussion ranges from the politics of nuclear energy and the hierarchical culture of the Soviet system, to lessons later applied during the Fukushima accident. Smith makes the case for nuclear power as a vital complement to renewables.

He also shares the story behind the Chernobyl Spirit Company – a social enterprise he has launched with Ukrainian colleagues, producing safe, high-quality spirits to support Ukrainian communities. Listen to find out whether Andrew Glester dared to try one.

The post Chernobyl at 40: physics, politics and the nuclear debate today appeared first on Physics World.

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Virgin Media O2 launches Europe’s first Starlink direct-to-smartphone service

British mobile operator Virgin Media O2 said it started offering satellite-to-smartphone connectivity in the United Kingdom Feb. 26, marking the first commercial deployment of Starlink’s Direct-to-Cell service in Europe.

The post Virgin Media O2 launches Europe’s first Starlink direct-to-smartphone service appeared first on SpaceNews.

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Airbus and Leonardo report increased space revenues for 2025

Marco Brancati

MILAN – Two of Europe’s largest primes, Airbus and Leonardo, reported increased revenues in their respective space businesses from last year. The results, which were announced earlier this week in separate earnings reports, come as the two companies are in discussions with Thales on a joint venture named Project Bromo. Neither discussed the topic on […]

The post Airbus and Leonardo report increased space revenues for 2025 appeared first on SpaceNews.

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LHCb upgrade: CERN collaboration responds to UK funding cut

Later this year, CERN’s Large Hadron Collider (LHC) and its huge experiments will shutdown for the High Luminosity upgrade. When complete in 2030, the particle-collision rate in the LHC will be increased by a factor of 10 and the experiments will be upgraded so that they can better capture and analyse the results of these collisions. This will allow physicists to study particle interactions at unprecedented precision and could even reveal new physics beyond the Standard Model.

Earlier this year, however, the UK government announced that it will no longer fund the upgrade of the LHCb experiment on the LHC, which is run by a collaboration of more than 1700 physicists worldwide. The UK had promised to contribute about £50 million to the upgrade – which is a significant chunk of the overall cost.

In this episode of the Physics World Weekly podcast I am in conversation with the particle physicist Tim Gershon, who is based at the UK’s University of Warwick. Gershon is spokesperson-elect for the LHCb collaboration and is playing a leading role in the upgrade.

Gershon explains that UK participation and leadership has been crucial for the success of LHCb and cautions that the future of the experiment and the future of UK particle physics have been imperilled by the funding cut.

We also chat about recent discoveries made by LHCb and look forward to what new physics the experiment could find after the upgrade.

The post LHCb upgrade: CERN collaboration responds to UK funding cut appeared first on Physics World.

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CesiumAstro acquires Vidrovr to embed AI in communications systems

SAN FRANCISCO – CesiumAstro announced the acquisition Feb. 26 of Vidrovr, a startup that specializes in artificial intelligence for multimodal signals analysis. Terms of the transaction, which closed in late 2025, were not disclosed. CesiumAstro acquired Vidrovr to accelerate its campaign to embed AI in space telecommunications and intelligence, surveillance and reconnaissance infrastructure, enabling radio-frequency […]

The post CesiumAstro acquires Vidrovr to embed AI in communications systems appeared first on SpaceNews.

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