‘Spooky’ quantum-entanglement experiments win physics Nobel

Davide Castelvecchi & Elizabeth Gibney

Nature | October 04, 2022

John Clauser (left), Anton Zeilinger and Alain Aspect have won this year’s Nobel physics prize for their research on quantum entanglement.Credit: J. Clauser (CC BY-SA 4.0), Matthias Röder/dpa/Alamy, The Royal Society (CC BY-SA 3.0)

Three quantum physicists have won the 2022 Nobel Prize in Physics for their experiments with entangled photons, in which particles of light become inextricably linked. Such experiments have laid the foundations for an abundance of quantum technologies, including quantum computers and communications.

Alain Aspect, John Clauser and Anton Zeilinger will each share one-third of the 10-million-kronor (US$915,000) prize.

“I was actually very surprised to get the call,” said Zeilinger, a physicist at the University of Vienna, at the press conference announcing the award. “This prize would not be possible without the work of more than 100 young people over the years.”

Particle’s surprise mass threatens to upend the standard model

Data from an old experiment finds that the mass of the W boson is higher than theory predicts, hinting at future breakthroughs.

Davide Castelvecchi and Elizabeth Gibney

Nature | April 07, 2022

The Tevatron particle collider at Fermilab in Batavia, Illinois, was once the world’s most powerful accelerator.Credit: Granger/Alamy

From its resting place outside Chicago, Illinois, a long-defunct experiment is threatening to throw the field of elementary particles off balance. Physicists have toiled for ten years to squeeze a crucial new measurement out of the experiment’s old data, and the results are now in. The team has found that the W boson — a fundamental particle that carries the weak nuclear force — is significantly heavier than theory predicts.

Physicists make most precise measurement ever of neutron’s lifetime

Davide Castelvecchi

Nature | October 15, 2021

The magnet array for the UCNτ experiment at Los Alamos National Laboratory, where physicists have measured the lifetime of the neutron with the highest ever precision.Credit: Los Alamos National Laboratory

Physicists have measured the lifetime of the neutron more precisely than ever before.

The average time it takes for the subatomic particle to decay is 877.75 seconds, according to an experiment that used magnetic fields to trap ultra-cold neutrons. The results have twice the precision of similar measurements, and are consistent with theoretical calculations. But they do not explain why in an alternative kind of experiment, neutrons last nearly 10 seconds longer.

The latest measurement was presented at a virtual meeting of the American Physical Society on 13 October, and published in Physical Review Letters¹.

The result is “very impressive”, says physicist Shannon Hoogerheide, who measures neutron lifetimes using a competing technique at the US National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland.

New type of dark energy could solve Universe expansion mystery

Davide Castelvecchi

Nature | September 17, 2021

Data from the Atacama Cosmology Telescope suggest the existence of two types of dark energy at the very start of the Universe.Credit: Giulio Ercolani/Alamy

Cosmologists have found signs that a second type of dark energy — the ubiquitous but enigmatic substance that is pushing the current Universe’s expansion to accelerate — might have existed in the first 300,000 years after the Big Bang.

Two separate studies — both posted on the arXiv preprint server in the past week^1,2 — have detected a tentative first trace of this ‘early dark energy’ in data collected between 2013 and 2016 by the Atacama Cosmology Telescope (ACT) in Chile. If the findings are confirmed, they could help to solve a long-standing conundrum surrounding data about the early Universe, which seem to be incompatible with the rate of cosmic expansion measured today. But the data are preliminary and don’t show definitively whether this form of dark energy really existed.

Is the standard model broken? Physicists cheer major muon result

PHYSICS

Davide Castelvecchi

Nature | April 07, 2021

The storage-ring magnet used for the g – 2 experiment at Fermilab. Credit: Reidar Hahn/Fermilab

Muons keep on misbehaving. An experiment in the United States has confirmed an earlier finding that the particles — massive, unstable cousins of the electron — are more magnetic than researchers originally expected. If the results hold up, they could ultimately force major changes in theoretical physics and reveal the existence of completely new fundamental particles.

Long-awaited muon physics experiment nears moment of truth

PHYSICS

Davide Castelvecchi

Nature | March 30, 2021

The storage-ring magnet used for the g – 2 experiment at Fermilab. Credit: Reidar Hahn/Fermilab

After a two-decade wait that included a long struggle for funding and a move halfway across a continent, a rebooted experiment on the muon — a particle similar to the electron but heavier and unstable — is about to unveil its results. Physicists have high hopes that its latest measurement of the muon’s magnetism, scheduled to be released on 7 April, will uphold earlier findings that could lead to the discovery of new particles.

The 10 Greatest Predictions in Physics

PHYSICS

physicsworld | January 19, 2021

Faces behind the theories Top row: Isaac Newton, Siméon-Denis Poisson, James Clerk Maxwell, Albert Einstein, Maria Goeppert Mayer, Julian Schwinger. Bottom row: Fred Hoyle, Chen-Ning Yang and Tsung-Dao Lee, Brian Josephson, Vera Rubin, W Kent Ford Jr. (Image sources, top row: Godfrey Kneller (1646–1723); François-Séraphin Delpech (1778–1825); AIP Emilio Segrè Visual Archives, Brittle Books Collection; Ferdinand Schmutzer, 1921; DoE; AIP Emilio Segrè Visual Archives, Physics Today Collection. Bottom row: Martyn Goddard/Shutterstock; NYPL/Science Source/Science Photo Library; CC BY SA Cavendish Laboratory/Kelvin Fagan; The Washington Times/Shutterstock; AIP Emilio Segrè Visual Archives, John Irwin Slide Collection)

Theoretical physicists stare at blackboards, do calculations and make predictions. Experimental physicists build equipment, gather observations and analyse data sets. (At least, that’s how it goes at the best of times.)

The two groups are reliant on each other – experimentalists may be trying to prove a theory is right (or wrong), or perhaps theorists are trying to explain experimental observations. As the British theoretical physicist Arthur Eddington once wryly put it, “Experimentalists will be surprised to learn that we will not accept any evidence that is not confirmed by theory.”

Physicists in China Challenge Google’s ‘Quantum Advantage’

QUANTUM MECHANICS 

Philip Ball

Nature | December 03, 2020

This photonic computer performed in 200 seconds a calculation that on an ordinary supercomputer would take 2.5 billion years to complete.Credit: Hansen Zhong

A team in China claims to have made the first definitive demonstration of ‘quantum advantage’ — exploiting the counter-intuitive workings of quantum mechanics to perform computations that would be prohibitively slow on classical computers.

Physicists Who Unravelled Mysteries of Black Holes Win Nobel Prize

NOBEL PRICE IN PHYSICS

Elizabeth Gibney & Davide Castelvecchi

Nature | October 06, 2020

Roger Penrose, Andrea Ghez and Reinhard Genzel (left to right) received the 2020 Nobel physics prize for their research on black holes.Credit: David Levenson/Getty, Christopher Dibble, ESO/M. Zamani

A mathematical physicist and two astronomers have won the 2020 Nobel Prize in Physics for discoveries relating to the most massive and mysterious objects in the Universe — black holes.

British mathematical physicist Roger Penrose, 89, receives half the prize for theoretical work that showed how Albert Einstein’s general theory of relativity should result in black holes, which have a gravitational pull so strong that even light cannot escape.