Terahertz microscope reveals the motion of superconducting electrons

Amazing stuff!

"... Now, MIT physicists have used terahertz light to reveal inherent, quantum vibrations in a superconducting material, which have not been observable until now. ...

In a paper appearing today in the journal Nature, the scientists report that they have developed a new terahertz microscope that compresses terahertz light down to microscopic dimensions. This pinpoint of terahertz light can resolve quantum details in materials that were previously inaccessible. ..."

From the abstract:

"The superconducting gap defines the fundamental energy scale for the emergence of dissipationless transport and collective phenomena in a superconductor.

In layered high-temperature cuprate superconductors, in which the Cooper pairs are confined to weakly coupled two-dimensional (2D) copper–oxygen (CuO2) planes, terahertz (THz) spectroscopy at subgap millielectronvolt (meV) energies has provided crucial insights into the collective superfluid response perpendicular to the superconducting layers. However, within the CuO2 planes, the collective superfluid response manifests as plasmonic charge oscillations at energies far exceeding the superconducting gap, obscured by strong dissipation.

Here we present spectroscopic evidence of a below-gap, 2D superfluid plasmon in few-layer Bi2Sr2CaCu2O8+x and spatially resolve its deeply subdiffractive THz electrodynamics. By placing the superconductor in the near field of a spintronic THz emitter, we reveal this distinct resonance—absent in bulk samples and observed only in the superconducting phase—and determine its plasmonic nature by mapping the geometric anisotropy and dispersion. Crucially, these measurements offer a direct view of the momentum-dependent and frequency-dependent superconducting transition in two dimensions."

Terahertz microscope reveals the motion of superconducting electrons | MIT News | Massachusetts Institute of Technology "For the first time, the new scope allowed physicists to observe terahertz “jiggles” in a superconducting fluid."

Imaging a terahertz superfluid plasmon in a two-dimensional superconductor (no public access)

Imaging a terahertz superfluid plasmon in a two-dimensional superconductor (appears to be a preprint, open access)

Terahertz Radar: A New Era in Auto Safety under any weather conditions, night and day

To have more than one kind of sensor on a car and not to relay on a single kind of sensor is probably a good idea! Unfortunately, this complicates things.

"... conditions that render nearly all of today’s car-mounted sensors useless: fog and bright early-morning sunshine. Radar can’t see small objects well, lidar is limited by fog, and cameras are blinded by glare. Carey and his cofounders decided to create a sensor that could have done the job—a terahertz imager. ...

But thanks to some intense engineering and improvements in silicon transistor frequency, beaming terahertz radiation over hundreds of meters is now possible. Teradar, the Boston-based startup Carey cofounded, has managed to make a sensor that can meet the auto industry’s 300-meter distance requirements. ..."

Terahertz Radar: A New Era in Auto Safety - IEEE Spectrum "Startup Teradar’s tech combines lidar’s precision with radar’s simplicity"

Teradar company

Teradar’s system can steer beams of terahertz radiation with no moving parts.