Breakthrough study published in Optica
30.03.2026
Researchers at the Technion – Israel Institute of Technology have, for the first time, measured the temporal duration of individual pulses of an extraordinary form of quantum light known as bright squeezed vacuum (BSV) . The findings were published in Optica , a leading journal in optics and photonics.
The study was led by Dr. Michael Krüger and Ph.D. student Yuval Kern from the Technion Faculty of Physics, Solid State Institute, and Helen Diller Quantum Center. The research was carried out in collaboration with Technion colleagues Prof. Oren Cohen, Prof. Pavel Sidorenko, and Prof. Ido Kaminer, with crucial contributions from Andrei Rasputnyi of the Max Planck Institute for the Science of Light in Erlangen, Germany.
Measuring the Unmeasurable
Bright squeezed vacuum is a unique quantum state of light. Although it is formally considered the “vacuum state” and the electric field of this light is zero on average, it exhibits enormous quantum fluctuations of its electric field due to the squeezing effect. This is in stark contrast to typical light produced by intense lasers, known as coherent-state light, that exhibit only extremely weak quantum fluctuations. However, for BSV, the fluctuations can lead to extremely intense light pulses, containing up to one trillion (10¹²) photons in a single pulse, hence the term bright squeezed vacuum. Until now, no one had measured the temporal duration of single BSV pulses.
Using a new interferometric technique, the Technion team was able to reconstruct the electric field of each individual quantum pulse. They combined the BSV light – which has very large quantum fluctuations – with carefully controlled laser pulses in a beam splitter. When the two light beams overlapped, they produced interference patterns. By recording many of these patterns and analyzing them, the researchers were able to determine the time-dependent electric field shape of every single pulse.
Their measurements revealed that each recorded BSV pulse lasts just around 27 femtoseconds (27 quadrillionths of a second), placing it firmly in the ultrafast regime. The researchers were also able to verify that when averaging over many pulses, the electric field of BSV is indeed close to zero – a tell-tale sign of a vacuum state of light.
A visual illustration of a bright squeezed vacuum—a quantum state of light characterized by an exceptionally high level of noise—as it interferes with a regular laser pulse at a beam splitter. By recording the resulting interference patterns, the real-time characteristics of the laser pulse can be reconstructed.
Image credit: Dr. Michael Krüger, Yuval Kern, Ido Nisim, and Dr. Adi Goldner
A Tool for Extreme Physics
Ultrashort and intense pulses are essential for driving highly nonlinear optical processes and observing electron motion in condensed matter systems on the attosecond time scale (1 one quintillionth of a second). The researchers believe that BSV could become a powerful tool for exploring extreme light–matter interactions. Because of its quantum nature, BSV is expected to interact more gently with materials compared to conventional coherent-state laser light. This property may enable scientists to investigate matter under extreme conditions without causing damage, a key goal for future experiments.
“This is just the beginning,” said Dr. Krüger. “Bright squeezed vacuum opens exciting possibilities for studying ultrafast electron dynamics and pushing the boundaries of nonlinear optics.”
The research marks a significant advance in quantum optics and ultrafast science, further strengthening the Technion’s leadership in fundamental and applied photonics research.
The full paper is available in Optica :
https://opg.optica.org/optica/fulltext.cfm?uri=optica-13-3-395
Optica
Experimental study
Not applicable
Single-shot pulse retrieval of femtosecond bright squeezed vacuum
20-Mar-2026