- Researchers use freely propagating electrons to see how light behaves beyond the limitations of wavelength.
- They were able to develop a new holographic method that captures nanoscale objects.
- It can open new doors for quantum computation.
The concept of the hologram was first discovered in 1948, but scientists weren’t able to create holograms until the invention of an appropriate light source, the laser, in 1960. Since then, holography expanded rapidly, both in fields of display and scientific imagery.
Optical holography has now become a popular method for 3D imaging of macroscopic materials and security applications. However, the spatial resolution of this method is limited by the light wavelength (1 micrometer). Thus, it cannot be used for imaging tinier (nanoscale) objects.
Recently, researchers at the Swiss Federal Institute of Technology came up with a technique that helps them observe how light behaves beyond the limitations of wavelength (at nanometric scale). They used a strange photographic media – freely propagating electrons.
Electrons Interact With Light
The direction of light and free electrons is a crucial parameter because unlike conventional photography, it is sensitive to the phase of light. After interacting with light, the electrons exist in superposition states with different energies.
If these electrons interact with another laser pulse, their states change rapidly based on the smallest delay between the two, exhibiting very different energy distribution. Researchers build a map of energy distributions to accurately figure out the position of light at a given moment.
Freely propagating electrons interact with light and change their state | Courtesy of researchers
In fact, they used this physical principle to create a real-time movie of lightwave propagating in the nanostructures at the finest time of space resolution.
A Way For Quantum Computation
In order to isolate the electron-reference and electron-imaging beams in energy, researchers utilized the quantum nature of the electron-light interaction. This enabled them to encrypt data on the electron wave function, using light pulses. It’s possible to map data with ultrafast transmission electron microscopy.
Overall, this new technique has 2 major advantages –
- Imaging electromagnetic fields with nanometer and attosecond precision in space and time.
- It can be applied to quantum computing applications to tune the quantum characteristics of free electrons.
The approach provides the highest spatial resolution than any other existing technique. Until now, technology has been limited to microscopic optical instruments that use freely propagating photons.
This is the first step to integrate and miniaturize light equipment onto integrated circuits. The study also opens up the possibility to better understand how light behaves in photonic computers nanoparticles and atoms.