A Soyuz spacecraft delivered two Russian cosmonauts and one American astronaut to the International Space Station Nov. 27 for an eight-month stay.
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ESA member states are contributing more than 22 billion euros for the next three years, very close to its overall goal but with some programs faring better than others.
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An effect first observed decades ago by Nobel laureate Arthur Ashkin has been used to fine tune the electrical charge on objects held in optical tweezers. Developed by an international team led by Scott Waitukaitis of the Institute of Science and Technology Austria, the new technique could improve our understanding of aerosols and clouds.
Optical tweezers use focused laser beams to trap and manipulate small objects about 100 nm to 1 micron in size. Their precision and versatility have made them a staple across fields from quantum optics to biochemistry.
Ashkin shared the 2018 Nobel prize for inventing optical tweezers and in the 1970s he noticed that trapped objects can be electrically charged by the laser light. “However, his paper didn’t get much attention, and the observation has essentially gone ignored,” explains Waitukaitis.
Waitukaitis’ team rediscovered the effect while using optical tweezers to study how charges build up in the ice crystals accumulating inside clouds. In their experiment, micron-sized silica spheres stood in for the ice, but Ashkin’s charging effect got in their way.
“Our goal has always been to study charged particles in air in the context of atmospheric physics – in lightning initiation or aerosols, for example,” Waitukaitis recalls. “We never intended for the laser to charge the particle, and at first we were a bit bummed out that it did so.”
Their next thought was that they had discovered a new and potentially useful phenomenon. “Out of due diligence we of course did a deep dive into the literature to be sure that no one had seen it, and that’s when we found the old paper from Ashkin, “ says Waitukaitis.
In 1976, Ashkin described how optically trapped objects become charged through a nonlinear process whereby electrons absorb two photons simultaneously. These electrons can acquire enough energy to escape the object, leaving it with a positive charge.
Yet beyond this insight, Ashkin “wasn’t able to make much sense of the effect,” Waitukaitis explains. “I have the feeling he found it an interesting curiosity and then moved on.”
To study the effect in more detail, the team modified their optical tweezers setup so its two copper lens holders doubled as electrodes, allowing them to apply an electric field along the axis of the confining, opposite-facing laser beams. If the silica sphere became charged, this field would cause it to shake, scattering a portion of the laser light back towards each lens.
The researchers picked off this portion of the scattered light using a beam splitter, then diverted it to a photodiode, allowing them to track the sphere’s position. Finally, they converted the measured amplitude of the shaking particle into a real-time charge measurement. This allowed them to track the relationship between the sphere’s charge and the laser’s tuneable intensity.
Their measurements confirmed Ashkin’s 1976 hypothesis that electrons on optically-trapped objects undergo two-photon absorption, allowing them to escape. Waitukaitis and colleagues improved on this model and showed how the charge on a trapped object can be controlled precisely by simply adjusting the laser’s intensity.
As for the team’s original research goal, the effect has actually been very useful for studying the behaviour of charged aerosols.
“We can get [an object] so charged that it shoots off little ‘microdischarges’ from its surface due to breakdown of the air around it, involving just a few or tens of electron charges at a time,” Waitukaitis says. “This is going to be really cool for studying electrostatic phenomena in the context of particles in the atmosphere.“
The study is described in Physical Review Letters.
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Earlier this autumn I had the pleasure of visiting the Perimeter Institute for Theoretical Physics in Waterloo Canada – where I interviewed four physicists about their research. This is the second of those conversations to appear on the podcast – and it is with Bianca Dittrich, whose research focuses on quantum gravity.
Albert Einstein’s general theory of relativity does a great job at explaining gravity but it is thought to be incomplete because it is incompatible with quantum mechanics. This is an important shortcoming because quantum mechanics is widely considered to be one of science’s most successful theories.
Developing a theory of quantum gravity is a crucial goal in physics, but it is proving to be extremely difficult. In this episode, Dittrich explains some of the challenges and talks about ways forward – including her current research on spin foams. We also chat about the intersection of quantum gravity and condensed matter physics; and the difficulties of testing theories against observational data.
IOP Publishing’s new Progress In Series: Research Highlights website offers quick, accessible summaries of top papers from leading journals like Reports on Progress in Physics and Progress in Energy. Whether you’re short on time or just want the essentials, these highlights help you expand your knowledge of leading topics.
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LONDON – London-headquartered ACME Space has unveiled plans to begin hardware tests of its balloon-launched orbital manufacturing vehicle Hyperion next year and hopes to commence commercial operations in 2027. The Hyperion Orbital Factory Vehicle (OFV) is designed to carry up to 200 kilograms to low Earth orbit (LEO), using a hydrogen-filled balloon to overcome the […]
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HELSINKI — Chinese commercial launch firm Landspace is preparing to attempt the country’s first orbital launch and booster landing this weekend with its Zhuque-3 rocket. Airspace closure notices issued under the Civil Aviation Administration of China (CAAC) indicate a launch attempt from the vicinity of Jiuquan Satellite Launch Center between around 11:00 p.m. Eastern Nov. […]
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ESA and Norway have signed a letter of intent and formed a joint working group to assess the feasibility of a new ESA Arctic Space Centre.
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Qubits – the building blocks of quantum computers – are plagued with a seemingly unsurmountable dilemma. If they’re fast, they aren’t robust. And if they’re robust, they aren’t fast. Both qualities are important, because all potentially useful quantum algorithms rely on being able to perform many manipulations on a qubit before its state decays. But whereas faster qubits are typically realized by strongly coupling them to the external environment, enabling them to interact more strongly with the driving field, robust qubits with long coherence times are typically achieved by isolating them from their environment.
These seemingly contradictory requirements made simultaneously fast and robust qubits an unsolved challenge – until now. In an article published in Nature Communications, a team of physicists led by Dominik Zumbühl from the University of Basel, Switzerland show that it is, in fact, possible to increase both the coherence time and operational speed of a qubit, demonstrating a pathway out of this long-standing impasse.
The key ingredient driving this discovery is something called the direct Rashba spin-orbit interaction. The best-known example of spin-orbit interaction comes from atomic physics. Consider a hydrogen atom, in which a single electron revolves around a single proton in the nucleus. During this orbital motion, the electron interacts with the static electric field generated by the positively charged nucleus. The electron in turn experiences an effective magnetic field that couples to the electron’s intrinsic magnetic moment, or spin. This coupling of the electron’s orbital motion to its spin is called spin-orbit (SO) interaction.
Aided by collaborators at the University of Oxford, UK and TU Eindhoven in the Netherlands, Zumbühl and colleagues chose to replace this simple SO interaction with a far more complex landscape of electrostatic potential generated by a 10-nanometer-thick germanium wire coated with a thin silicon shell. By removing a single electron from this wire, they create states known as holes that can be used as qubits, with quantum information being encoded in the hole’s spin.
Importantly, the underlying crystal structure of the silicon-coated germanium wire constrains these holes to discrete energy levels called bands. “If you were to mathematically model a low-level hole residing in one of these bands using perturbation theory – a commonly applied method in which more remote bands are treated as corrections to the ground state – you would find a term that looks structurally similar to the spin–orbit interaction known from atomic physics,” explains Miguel Carballido, who conducted the work during his PhD at Basel, and is now a senior research associate at the University of New South Wales’ School of Electrical Engineering and Telecommunications in Sydney, Australia.
By encoding the quantum states in these energy levels, the spin-orbit interaction can be used to drive the hole-qubit between its two spin states. What makes this interaction special is that it can be tuned using an external electric field. Thus, by applying a stronger electric field, the interaction can be strengthened – resulting in faster qubit manipulation.
This ability to make a qubit faster by tuning an external parameter isn’t new. The difference is that whereas in other approaches, a stronger interaction also means higher sensitivity to fluctuations in the driving field, the Basel researchers found a way around this problem. As they increase the electric field, the spin-orbit interaction increases up to a certain point. Beyond this point, any further increase in the electric field will cause the hole to remain stuck within a low energy band. This restricts the hole’s ability to interact with other bands to change its spin, causing the SO interaction strength to drop.
By tuning the electric field to this peak, they can therefore operate in a “plateau” region where the SO interaction is the strongest, but the sensitivity to noise is the lowest. This leads to high coherence times (see figure), meaning that the qubit remains in the desired quantum state for longer. By reaching this plateau, where the qubit is both fast and robust, the researchers demonstrate the ability to operate their device in the “compromise-free” regime.
So, is quantum computing now a solved problem? The researchers’ answer is “not yet”, as there are still many challenges to overcome. “A lot of the heavy lifting is being done by the quasi 1D system provided by the nanowire,” remarks Carballido, “but this also limits scalability.” He also notes that the success of the experiment depends on being able to fabricate each qubit device very precisely, and doing this reproducibly remains a challenge.
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Victoria, Canada / Seoul, South Korea – November 27th, 2025 – Pacific Geomatics Limited (PacGeo), a Canadian satellite imagery distributor, today announced a strategic partnership with SI Analytics (SIA), a […]
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ESA wrapped up the first day of a critical ministerial conference sounding upbeat about progress in securing funding for the next three years, despite a few warning signs.
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SmartSky Networks does not plan to seek an injunction to block Gogo’s 5G air-to-ground rollout across the United States, despite prevailing in a patent-infringement lawsuit tied to the technology.
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