Quantum light gives a 20-fold boost to ultrafast laser processes

May 30, 2026 report Quantum light gives a 20-fold boost to ultrafast laser processes Sam Jarman Author Gaby Clark Scientific Editor Robert Egan Associate Editor Nonlinear interactions between light and matter are at the heart of some of the most powerful tools in modern optics, but pushing these processes to their limits has long been hampered by a fundamental constraint: the stronger you make the laser, the more likely it is to destroy whatever it illuminates. Through new experiments detailed in Nature, Jian Wu and colleagues at East China Normal University in Shanghai have found a way around this problem, by exploiting the quantum nature of light itself. The laser damage threshold Most optical processes are linear: if an atom is illuminated by a laser, it will absorb one photon at a time, producing a response that scales straightforwardly with the light's intensity. In contrast, nonlinear processes require several photons to arrive at an atom essentially simultaneously, producing effects including the simultaneous absorption of multiple photons, and the re-emission of light at several times the frequency of the original laser. Compared with linear processes, these effects scale far more steeply with the light's intensity, making them especially useful for physicists. However, this often requires the use of very intense laser pulses, which can damage or even destroy the materials they interact with. So far, this has placed a ceiling on how far the approach can be pushed. Boosting energy To address this problem, Wu's team turned to a form of quantum light known as a bright squeezed vacuum (BSV). Unlike ordinary laser light, where photons arrive at a predictable rate, a BSV state is characterized by extreme swings in the number of photons arriving at any given instant. These fluctuations mean that even at modest average power, a BSV pulse can deliver enormous bursts of photons: enough to drive nonlinear processes that would normally require a far more intense laser. To test this concept, the researchers used a key nonlinear process called tunneling ionization, where an intense light field distorts the electric environment around a sodium atom so severely that an electron can effectively punch straight through the barrier holding it in place. When they measured the energies and momentum of the liberated electrons, the researchers found that a BSV pulse carrying just 300 nanojoules of energy on average produced the same nonlinear effect as a conventional laser pulse—a more than 20-fold enhancement, achieved with no increase in average power. The team also showed that they could dial the pulse's intensity up or down at will, without changing its energy at all. Unlocking attosecond physics The results open up a new way of controlling strong-field processes by fine-tuning the quantum character of the light source. This could prove significant for attosecond science, involving pulses of light lasting just billionths of a billionth of a second. Until now, this field has relied almost entirely on classical laser sources—but by bringing quantum optical tools into this domain, the team's results could point toward a future where extreme light–matter interactions can be driven and controlled with far greater precision, and with far less risk of collateral damage, than has previously been possible. Written for you by our author Sam Jarman, edited by Gaby Clark, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you. Publication details Zhejun Jiang et al, Nonlinear atomic tunnelling boosted by bright squeezed vacuum, Nature (2026). DOI: 10.1038/s41586-026-10485-9 Journal information: Nature Key concepts Atomic & molecular processes in external fieldsOptics & lasersQuantum correlations, foundations & formalismPhotoelectron techniques© 2026 Science X Network