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- Researchers used entangled electrons in helium atoms to supply higher-energy X-rays past the restrict predicted by customary concept, doubtlessly opening a brand new strategy to quantum sensing.
- Two correlated electrons returned to the identical ion concurrently and launched their mixed vitality as a single X-ray photon, an impact noticed for the primary time.
- The tactic might assist detect paired-electron correlations in gases and supplies, with doable purposes in quantum computing and superior nanomaterials.
- Artist’s rendering of an ultraviolet laser pulse (darkish blue waves in foreground) appearing on a helium atom (middle). Two electrons are pulled away and pushed again (pale blue spiral waves hint their return). Once they recombine, they emit gentle at excessive ultraviolet frequencies (violet waves) and X-rays (white). (Tenio Pompmintchev lab / UC San Diego)
PRESS RELEASE — When sure atoms are irradiated with laser gentle, they will produce laser pulses with extraordinarily excessive frequencies within the X-ray vary. Till now, the theoretical mannequin of this impact predicted an higher restrict to the vitality, referred to as the vitality cutoff. Previous this level, hardly any X-rays are produced.
New analysis from the College of California San Diego, TU Wien (Austria) and the College of Salamanca (Spain) succeeds in overcoming this cutoff. Utilizing helium atoms, the researchers reached a a lot greater vitality vary than customary concept predicts, as a result of the atom’s two electrons can launch their vitality collectively as a single X-ray photon.
For this experiment, UC San Diego Assistant Professor of Physics Tenio Popmintchev’s group used intense UV lasers and helium atoms. The primary electron is launched and accelerated, adopted by the second. The 2 electrons will not be unbiased of each other, however are quantum-mechanically correlated and entangled from the second they’re freed till the second they return.
Utilizing UV driving pulses, the group might prepare for each electrons to recombine with the identical ion at precisely the identical immediate, releasing their mixed vitality as one higher-energy X-ray photon. This double-electron recombination is the reverse of a course of by which a single photon ejects two electrons directly — one thing that may occur solely as a result of the electrons are correlated. Right here it has been noticed for the primary time.
Secondary plateaus have additionally been reported by an analogous course of in quantum supplies, elevating the open and testable query of whether or not these options represent a singular fingerprint of strongly correlated dynamics — and thus an all-optical quantum sensor of paired-electron correlations not solely in gases but additionally in condensed matter — studying them out with ultrafast precision.
The reply issues for quantum computing, the place correlation and entanglement between electrons are the assets being engineered, and for the design of superior nanomaterials, whose properties are ruled by the identical interactions.
“For the primary time, we will see two entangled electrons return to the identical ion on the identical immediate and quit their vitality as a single X-ray photon. That offers us an X-ray fingerprint of electron correlation — the physics underlying each quantum computing and, doubtlessly, the design of superior nanomaterials,” mentioned Popmintchev.
The research was revealed August 7, 2026 in Nature Photonics. UC San Diego authors are Siyang Wang, Jieyu Yan, Sirius Track, Aleksander Prodanov, Zhihan Wu and Tenio Popmintchev. Their analysis was funded, partially, by the Alfred P. Sloan Basis (FG-2018-10892) and the European Analysis Council (XSTREAM-716950).
Learn the research in Nature Photonics: “Correlated electrons extend X-ray high-harmonic generation beyond the single-electron limit.”
