Quantum photonic technologies set to be more reliable with new interferometer

A growing number of emerging quantum applications operate using optical technologies. Basically, photons carry information at the speed of light and over long distances, making them good candidates for fast and secure communications and quantum computing. Many of these applications require photos that are identical (indistinguishable). When the photons are not identical, this can lead to errors in the data and quantum technologies become less reliable.

Currently, quantum photon sources are regularly taken offline to be tested and adjusted using an interferometer. This requires comparing photons many times using different configurations, a time-consuming process that requires relatively large devices that can accommodate different physical arrangements.

Real-time analysis of photon indistinguishability that can be performed inside a device while it is operating could improve the accuracy of quantum technologies.

Researchers at TMOS, the ARC Center of Excellence for Transformative Meta-Optical Systems, have designed and demonstrated a new device that uses an ultra-thin metasurface to make all the necessary measurements in a single pass. The work was reported in Optics.

Co-author Jihua Zhang says, “This metasurface-activated multiport interferometer can determine whether the properties of a photon pair are identical in a single shot. There is no need for multiple measurements using phase or time delays because the multiport structure allows the device to run the measurements simultaneously. This enables real-time and accurate characterization.”

A key advantage is that this multiport interferometer is single-element, which not only reduces the size, but also makes it ultrastable when compared to previous multiport interferometers in the free-space optical configuration.

The use of meta-optics further reduces device size, weight and power, as well as manufacturing cost. Flat optics, as meta-optics has become known, is the key to the miniaturization of optical systems, which in turn will lead to the miniaturization of the devices we use every day. it

Co-author Jinyong Ma says, “We created a static, dielectric metasurface grating without any reconfigurable elements. The grating was designed using multi-factor topology optimization, which essentially adjusts the surface pattern to interact with light in a way specific After successful simulations, fabrication, and a single calibration, we were able to successfully characterize the similarity of the photon’s spatial mode, polarization, and spectrum.

Principal investigator Andrey Sukhorukov, who is leading the research from the Australian National University, says: “The success of our experimental evidence suggests that the work can be developed further to also measure the indistinguishability of other photon properties, such as orbital angular momentum. They may support ultracompact and energy-efficient optical elements, which would be particularly suitable for portable and satellite-based free-space quantum photonic technologies.”