Researchers from the University of Tokyo and NTT Corporation have successfully generated strongly nonclassical light using a modular waveguide-based light source. By combining a waveguide Optical Parametric Amplifier (OPA) module created for quantum experiments and a specially designed photon detector, researchers were able to produce light in a superposition of coherent states. The achievement represents a crucial step toward creating faster and more practical optical quantum computers.
Continuous wave squeezed light is used to generate the various quantum states necessary to perform quantum computing. For the best computing performance, the squeezed light source must exhibit very low levels of light loss and be broadband, meaning it includes a wide range of frequencies.
OPAs use nonlinear optical crystals to generate squeezed light, but conventional OPAs don’t generate the quantum light with the properties necessary for faster quantum computing. To overcome this challenge, the researchers developed an OPA based on a waveguide-type device that achieves high efficiency by confining light to a narrow crystal.
By carefully designing the waveguide and manufacturing it with precision processing, they were able to create an OPA device with much smaller propagation loss than conventional devices. It can also be modularized for use in various experiments with quantum technologies.
The OPA device was designed to create squeezed light at telecommunications wavelengths, a wavelength region that tends to exhibit low losses. To complete the system, researchers needed a high-performance photon detector that worked at telecom wavelengths. However, standard photon detectors based on semiconductors don’t meet the performance requirements for this application.
Thus, researchers from University of Tokyo and National Institute of Information and Communications Technology (NICT) developed a detector designed specifically for quantum optics. The new superconducting nanostrip photon detector (SNSPD) uses superconductivity technology to detect photons.
The researchers are now looking at how to combine high-speed measurement techniques with the new waveguide OPA to get closer to their goal of ultrafast optical quantum computing. (Optica)
The study has been published in the journal Optics Express.
