Chip Circuit for Light Could Be Applied to Quantum Computations

Chip Circuit for Light Could Be Applied to Quantum Computations

The ability to transmit and manipulate the smallest unit of light, the photon, with minimal loss, plays a pivotal role in optical communications as well as designs for quantum computers that would use light rather than electric charges to store and carry information.


Now, researchers at the National Institute of Standards and Technology (NIST) and their colleagues have connected on a single microchip quantum dots — artificial atoms that generate individual photons rapidly and on-demand when illuminated by a laser — with miniature circuits that can guide the light without significant loss of intensity.


Future versions of the new photonic circuits will feature low-loss waveguides—the channels through which the single photons travel--some 3 meters long but tightly coiled to fit on a chip. The long waveguides will allow researchers to more precisely choose the time intervals (Δt) when photons exit different channels to rendezvous at a particular location.


Credit: NIST


To create the ultra-low-loss circuits, the researchers fabricated silicon- nitride waveguides—the channels through which the photons traveled—and buried them in silicon dioxide. The channels were wide but shallow, a geometry that reduced the likelihood that photons would scatter out of the waveguides. Encapsulating the waveguides in silicon dioxide also helped to reduce scattering.


Illustration shows some of the steps in creating the new ultra-low-loss photonic circuit on a chip. A microprobe lifts a gallium arsenide device containing a quantum dot—artificial atoms that generate single photons—from one chip. Then the probe places the quantum-dot device atop a low-loss silver-nitride waveguide built on another chip.


Credit: S. Kelley/NIST


The scientists reported that their prototype circuits has a loss of intensity only one percent that of similar circuits, also using quantum dots, that were fabricated by other teams. ..

Support the originator by clicking the read the rest link below.