Quantum Computing Closer to Practical

In a development that brings practical quantum computers closer to reality, a team of researchers demonstrated that they could create heralded single photons from a CMOS-compatible silicon chip operating at room temperature in the near-infrared (Appl. Phys. Lett. 100, 261104). The work was done by a collaboration of researchers from the National Institute of Standards and Technology; University of California, San Diego; Politecnico di Milano in Italy; and the IBM Thomas J. Watson Research Center. This paper was one of three finalists in OSA’s Theodore Maiman Student Paper Competition.

Optical quantum computers can theoretically provide radically faster information processing than current technologies, but creating the technology to apply quantum photonics will require that all the necessary devices be integrated and compatible. Pairs of correlated photons are the basis for many quantum computing processes, so the ability to generate these pairs is important. With “heralded” photons, the existence of one photon is announced by the detection of its partner. Heralded pairs of photons could be used in the future to trigger the storage of information in quantum-based computer memories.

The researchers designed the device to enable the nonlinear optical process of four-wave mixing in the silicon waveguide, and to allow a pump beam at 1,549.6 nm to generate photon pairs at 1,529.5 nm and 1,570.5 nm.

The ability to create photons around 1,550 nm eases integration with telecom fiber optics and integrated photonics, while the use of silicon provides a relatively inexpensive substrate material and allows for well-developed fabrication methods.