New nanophotonic circuits demonstrate the potential of quantum networks

The Purdue University team in the United States has captured alkali metal atoms (cesium) in integrated photonic circuits, which can serve as transistors for photons (the smallest energy unit of light). These captured atoms demonstrate for the first time the potential of cold atom integrated nanophotonic circuits to construct quantum networks. The research results were published in the latest issue of Physical Review X.

The newly developed technology utilizes laser cooling to capture atoms in integrated nanophotonic circuits. Light propagates through a tiny photon "line" (a waveguide that is 1/200 thinner than a human hair). These atoms are frozen to minus 273.15 degrees Celsius and are essentially in a static state. At such low temperatures, atoms can be captured by a pulling beam aimed at a photonic waveguide and placed at a distance much shorter than the wavelength of light (approximately 300 nanometers). Within this distance, atoms can effectively interact with photons in the photonic waveguide.

Researchers are conducting experiments
Using the most advanced nanomanufacturing instruments, the team designed a photonic waveguide into a circular structure with a diameter of approximately 30 microns, forming a so-called micro ring resonator. Light will circulate within the micro ring resonator and interact with the captured atoms.

This atomic coupled micro ring resonator is like a transistor for photons. People can use these captured atoms to control the flow of light through circuits. If atoms are in the correct state, photons can be transmitted through circuits. If the atom is in another state, photons will be completely blocked. The stronger the interaction between atoms and photons, the more effective the "gate" of passage and obstruction.

The team captured up to 70 atoms, coupling them all to photons and controlling their transmission on an integrated photonic chip, achieving a "collective" high-intensity interaction with light.

This research result can provide photon links for future distributed quantum computing based on neutral atoms. It can also serve as a new experimental platform for studying light matter interactions or ultra cold molecules.

Source: Opticsky