For the first time light mimics a a Nobel Prize quantum effect

Nothing in the press release says anything about how big these quantised steps are, let alone what determines the size of the steps. The original paper

The University of Montreal may have discovered something interesting, but they've done a totally hopeless job of telling the world what it might be good for.

I downloaded the paper:

It is interesting, so much happening in the quantum world. We need simplicity, a mechanism, I stay with EM radiation is a state of the Le Sage particles.. (Ducks))

You'd be right at home on sci.physics.relativity because there are people there who are even more pig-ignorant than you are.

Jan Panteltje snipped-for-privacy@comet.invalid wrote or quoted:

The researchers are studying how light behaves in a special kind of optical material where its movement mimics that of electrons in a topological solid - systems that have unusual, robust properties.

They want to measure a number called the Chern number, which indi- cates how the light waves wrap around in this system, much like how a globe's surface wraps around itself.

To do that, they shine a focused laser beam into the material and look at how the light shifts sideways when they apply an electric field.

This sideways motion is similar to how electric charges drift in the Hall effect. However, other ordinary effects can cause similar side- ways shifts, which would confuse the measurement.

To fix this, they cleverly alternate ("modulate") the artificial field in time and repeat the experiment for systems where the topological property (the Chern number's sign) is reversed. Because only the gen- uine topological part depends on that sign, by comparing the two cas- es they cancel all the unwanted background effects. Their simulations and measurements confirm that this approach lets them isolate the true topological signal.

For readers with some background in mathematics and physics:

The experiment measures the photonic analogue of the anomalous Hall current to extract the Chern number of a photonic band. The idea stems from theoretical work linking the Berry curvature to a trans- verse shift in the light's intensity profile when a synthetic elec- tric field (a gradient of on-site potential) is applied in a driven- dissipative lattice.

In practice, they measure the transverse displacement δr_x induced by a force E_y , integrating the resulting Berry curvature across the Brillouin zone by scanning over laser ω_L. However, the observed sig- nal also contains non-Berry terms - linked to the quantum metric and ordinary band dispersion - that obscure the topological contribution. While these average to zero theoretically, in real experiments they can be large and unstable, introducing noise.

To suppress these terms, the researchers introduce temporal modula- tion of the potential (making the synthetic field oscillate), which removes all field-independent (DC) contributions after demodulation. Then, by subtracting measurements from systems with opposite topolog- ical phases (ϕ_h=±π/2), they eliminate all residual non-Berry terms since only the Berry curvature changes sign. Simulations confirm that this double-cancellation (temporal modulation + topological phase re- versal) effectively isolates the Berry curvature's contribution, en- abling accurate extraction of the quantized Chern number in a photon- ic platform.

I think that electrons have a specific mass and charge. Same for protons. Basic question. Have the mass and charge of the electron and proton been clearly and coherently derived from the photoelectric effect? Could any of you provide links to web pages that show how this is calculated in as simple a manner as possible?

That's a more comprehensible explanation of what is going on, but still leaves me wondering what it might be good for.

snipped-for-privacy@zedat.fu-berlin.de (Stefan Ram) wrote or quoted:

This was cross-posted to sci.electronics.design; so especially for the readers of sci.electronics.design, let me add that this reminds me of something electronic, the lock-in amplifier!

It would be cool if it could produce an optical modulator or deflector.

Lithium niobate isn't the ideal stuff. Mach–Zehnders are inherently tricky, the small difference between big numbers problem.

Optical PLZTs keep being the stuff of the future, but they are hard to drive.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics