Let’s talk about a pretty wild leap in ultrafast quantum optics: a quantum light field squeezer that can actually generate and manipulate squeezed light on attosecond timescales. Researchers from the University of Arizona and ICFO led the charge here, pushing squeezed-light science into a zone where you can shape and measure the tiniest flickers of light—one oscillation at a time. It’s hard not to imagine some big shifts for quantum metrology, strong-field physics, and condensed-matter research coming out of this.
Breaking New Ground in Squeezed-Light Generation
Squeezed light is all about shuffling quantum noise between pairs of observables. It’s been a workhorse for precision measurements and quantum tech. But until now, squeezing usually meant narrow bandwidths and slow temporal action.
This new quantum light field squeezer (QLFS) breaks out of that box. It works right on few-cycle laser pulses, which is a game-changer.
The team used degenerate four-wave mixing in a quasi-collinear focusing setup. That move sidestepped the typical phase-matching headaches that limit broadband squeezing. So, they managed to generate intensity- and phase-squeezed states straight from ultrashort pulses at 790 nm. No need for complicated post-processing or optical cavities.
Overcoming Broadband Phase-Matching Limits
This clever geometry lets nonlinear interactions happen efficiently over a huge range of wavelengths. By tweaking the focusing and the angles, the researchers unlocked squeezing across the entire bandwidth of few-cycle pulses.
Most people would’ve called that impossible with standard nonlinear optics, but here we are.
Attosecond-Resolved Quantum Dynamics
One of the coolest results? They could watch squeezing dynamics unfold on attosecond timescales. Ultrafast optical metrology showed that squeezing isn’t just sitting still inside a pulse. It actually changes a lot across each half-cycle of the electric field.
Squeezing levels dropped to their lowest when the field intensity hit zero. That kind of time-dependent behavior points to a seriously nonclassical structure in the light—something you’d totally miss if you just averaged over time.
Measuring Squeezing in Few-Cycle Pulses
For measurements, the team sampled the waveforms of few-cycle pulses using dielectric reflectivity. They looked at intensity-difference statistics across tons of laser shots and compared those to coherent-state references.
That let them piece together effective Wigner representations of the squeezed light.
Quantum Signatures Beyond Classical Light
When they analyzed those reconstructed states, a pretty clear trend popped up: intensity uncertainty followed a similar pattern for each half-cycle. That’s nothing like what you see in classical coherent fields.
To see what this means in practice, the team ran simulations of high-harmonic generation (HHG) with different quantum light states. The results were telling:
Photon Statistics and Harmonic Emission
They crunched some second-order photon-correlation numbers. Time-dependent squeezing left real, measurable fingerprints on both the harmonic spectra and photon statistics.
That means the quantum state of the driving light is directly tied to strong-field emission. Pretty wild, right?
Toward Active Quantum-State Engineering
The QLFS stands out for how much you can tune it. Adjusting pulse delay and phase-matching angle gave the researchers attosecond-scale control over the squeezed quadrature and its uncertainty.
That opens the door to active quantum-state engineering in ways that used to be totally out of reach.
They also showed that quantum light–induced tunneling currents respond to nonclassical intensity-noise stats. This hints at fresh ways to steer strong-field and solid-state effects on sub-femtosecond timescales.
Implications for Ultrafast Quantum Science
This work pushes squeezed-light generation into the ultrafast and attosecond domains.
That shift opens up some intriguing possibilities:
After spending decades in optical science, I can’t help but see this as a huge leap. Now, quantum noise isn’t just a slow, averaged-out thing—it’s a resource we can actually control, evolving right inside each oscillation of light.
Here is the source article for this story: Advances In Ultrafast Optics Unlock Attosecond Control Of Few-Cycle Laser Pulses