Ultra-fast quantum light detector paves the way for better quantum computers

Researchers have developed a tiny device that paves the way for better quantum computers and quantum communications, making them significantly faster than the current state of the art.

Bristol researchers have developed a tiny device that paves the way for better quantum computers and quantum communications, making them significantly faster than the current state of the art.

Researchers from Bristol UniversityQuantum Engineering Technology Labs (QET Labs) and the Université Côte d’Azur have designed a new miniaturized light detector to measure quantum characteristics of light in greater detail than ever before. The device, made up of two silicon chips working together, was used to measure the unique properties of quantum light “compressed” at record speeds.

Harnessing the unique properties of quantum physics promises new avenues to surpass the current state of the art in computing, communication, and measurement. Silicon photonics – where light is used as an information carrier in silicon microchips – is an exciting path to these next generation technologies.

“Pressed light is a very useful quantum effect. It can be used in quantum communications and quantum computers and has already been used by the LIGO and the Virgo gravitational wave observatories to enhance their sensitivity, helping to detect exotic astronomical events such as black hole mergers. So improving the means of measuring it can have a big impact, ”said Joel Tasker, co-lead author.

Measuring compressed light requires detectors designed for ultra-low electronic noise, in order to detect low quantum characteristics of light. But these detectors have so far been limited in the speed of the signals that can be measured – around a thousand million cycles per second.

“This has a direct impact on the processing speed of emerging information technologies such as optical computers and communications with very low light levels. The higher the bandwidth of your detector, the faster you can perform calculations and transmit information, ”said Jonathan Frazer, co-lead author.

The integrated detector has so far been clocked an order of magnitude faster than the previous state of the art, and the team is working to refine the technology to go even faster.

The footprint of the detector is less than a square millimeter – this small size enables the high speed performance of the detector. The detector is built from silicon microelectronics and a silicon photonic chip.

Around the world, researchers have explored how to integrate quantum photonics on a chip to demonstrate evolutionary fabrication.

“A lot of the focus has been on the quantum part, but now we have started to integrate the interface between quantum photonics and electrical reading. This is necessary for the whole quantum architecture to function efficiently. For homodyne detection, the chip-wide approach results in a device with a small footprint for mass production and, most importantly, improves performance, ”said Professor Jonathan Matthews, who led the project. .

Reference: “Silicon photonics interfaced with integrated electronics for the 9 GHz measurement of compressed light” by Tasker, J. et al., November 9, 2020, Photonics of nature.
DOI: 10.1038 / s41566-020-00715-5

Support for this work includes the Matthews European Research Council seed grant ERC-2018-STG 803665 “Photonics for Engineered Quantum Enhanced Measurement”, which aims to improve on-chip quantum detection capabilities and the Research Council in engineering and physical sciences which funded the scholarship of principal authors Joel Tasker and Jonathan Frazer. All sources of funding are described in the entire document.

The University of Bristol’s Quantum Engineering Technology Labs (QET Labs) was launched in April 2015 and encompasses the activity of more than 100 academics, staff and students. It brings together the broader quantum activity and related activities in Bristol to maximize the opportunities for new scientific discoveries that underpin the development of engineering and technology.

The EPSRC-funded Bristol Quantum Engineering Center for Doctoral Education provides an exceptional training and development experience for those who wish to pursue a career in the emerging quantum technology industry or academia. It supports the understanding of sound fundamental scientific principles and their practical application to real-world challenges.