A new photonic chip could be a significant step toward enabling photonic quantum information processors. It can generate and measure quantum states of light in ways previously only possible with large and costly laboratory equipment.
The chip is built with lithium niobate, a salt whose crystals have numerous applications in optics. On one side of the chip, it generates squeezed states of light and measures them on the other. To put it simply, a squeezed state of light is light that has been made less noisy at the quantum level. Squeezed states of light have recently been used to improve the sensitivity of LIGO, the observatory that detects gravitational waves using laser beams. The same less-noisy state of light is required when processing data with light-based quantum devices.
The quality of the quantum states obtained exceeds the requirements for quantum information processing, which was previously the domain of large experimental setups. The study is a significant step toward generating and measuring the quantum states of light in an integrated photonic circuit.
The technology paves the way for the eventual development of terahertz clock-rate quantum optical processors. In comparison, the electronic processor in a MacBook Pro is thousands of times faster. The technology may find practical applications in communications, sensing, and quantum computing in the next five years.