Nanoscale Mirror With Only 2000 Atoms

Nanoscale Mirror With Only 2000 Atoms
An array of about 2000 cold atoms trapped in the vicinity of a nanoscale fiber enables to realize an efficient mirror for the guided light. Credit: Laboratoire Kastler Brossel – N.V. Corzo

Mirrors are the easiest way to manipulate light propagation. ProfessorJulien Lauret and his team at Pierre and Marie Curie University in Paris have developed a new efficient mirror. Generally, a mirror consists of a very large number of atoms. But, this novel mirror is composed of only 2,000 atoms.

Scientists engineer the position of cold atoms captured around a nanoscale fiber. By doing this, scientists have fulfilled the necessary requirement of Bragg reflection. (Bragg reflection is a well-known physical effect first discover by William Lawrence Bragg and his father William Henry Bragg in crystalline solids. It gives the angles for coherent and incoherent scattering from a crystal lattice.

In the current experiment, each captured atom contributes a small reflectance and the engineered position allows the constructive interference of multiple reflections.

Neil Corzo said, “Previous demonstrations in free space require tens of millions of atoms to get the same reflectance. But, now only 2000 atoms captured in the vicinity of the fiber. This is due to the strong atom-photon coupling and the atom position control that we can now achieve in our system.”

The main component nanoscale fiber has a diameter of only 400nm. A large fraction of the light travels outside the fiber in a transient field. It heavily focuses on the 1-cm nanofiber length. By using this strong transversal confinement, cold caesium atoms was captured around the fiber in well-defined chains. By implementing whole-fibered dipole trap, it is possible to capture atoms.

Scientists then used well-chosen pairs of beams to produce two chains of trapping potentials around the fiber. But, only one atom can occupy each site. They then choose the correct colours of the trap beams. After that, scientists calculate the distance between atoms in the chains. Through this, they get closer to half the resonant wavelength of the caesium atoms.

This setting represents an essential step in the arriving field of waveguide quantum electrodynamics. According to scientists, it has applications in quantum networks, quantum nonlinear optics, and quantum simulation. It will also allow for novel quantum network capabilities and many-body effects arising from long-range interactions between multiple spins, a daunting prospect in free space.