Researchers are developing the world’s smallest quantum light detector on a silicon chip

Researchers from the University of Bristol have made a major breakthrough in scaling up quantum technology by integrating the world’s smallest quantum light detector on a silicon chip. The paper, “A Bi-CMOS electronic photonic integrated circuit quantum light detector,” was published in Scientific progress.

A pivotal moment in unlocking the information age was when scientists and engineers were able to miniaturize transistors on inexpensive microchips for the first time in the 1960s.

Now, for the first time, academics from the University of Bristol have demonstrated the integration of a quantum light detector – smaller than a human hair – onto a silicon chip, bringing us one step closer to the era of quantum technologies that use light.

Making high-quality electronics and photonics at scale is fundamental to realizing the next generation of advanced information technologies. Figuring out how to create quantum technologies in existing commercial facilities is an ongoing international effort tackled by university research and companies around the world.

Being able to create high-performance quantum hardware at scale could be critical for quantum computing due to the sheer volume of components expected to build even a single machine.

In pursuit of this goal, researchers at the University of Bristol have demonstrated a type of quantum light detector implemented on a chip with a circuit spanning 80 micrometers by 220 micrometers.

Crucially, the small size means the quantum light detector can be fast, which is essential for unlocking high-speed quantum communications and enabling fast operation of optical quantum computers.

The use of established and commercially accessible manufacturing techniques increases the prospects for early integration into other technologies such as sensing and communications.

“These types of detectors are called homodyne detectors and they are popping up everywhere in quantum optics applications,” explains Professor Jonathan Matthews, who led the research and is director of the Quantum Engineering Technology Labs.

“They work at room temperature, and you can use them for quantum communications, in incredibly sensitive sensors – like state-of-the-art gravitational wave detectors – and there are designs of quantum computers that would use these detectors.”

In 2021, the Bristol team showed how coupling a photonics chip to a separate electronics chip can increase the speed of quantum light detectors. Now with a single electronic-photonic integrated chip, the team has been able to increase speed by another factor of 10 while reducing the footprint. by a factor of 50.

Although these detectors are fast and small, they are also sensitive.

“The key to measuring quantum light is sensitivity to quantum noise,” explains author Dr. Giacomo Ferranti from.

‘Quantum mechanics is responsible for a minimal fundamental noise level in all optical systems. The behavior of this noise reveals information about what kind of quantum light is traveling in the system, it can determine how sensitive an optical sensor can be, and it can determine how sensitive an optical sensor can be. can be used to mathematically reconstruct quantum states. In our study, it was important to show that making the detector smaller and faster did not block its sensitivity for measuring quantum states.”

The authors note that there is even more exciting research to be done on integrating other disruptive quantum technology hardware down to the chip scale. The new detector should improve efficiency and further work needs to be done to test the detector in many different applications.

Professor Matthews added: “We built the detector in a commercially accessible foundry to make its applications more accessible. While we are incredibly excited about the implications of a range of quantum technologies, it is critical that we as a community continue to tackle the challenge of scalable quantum technology manufacturing.

“Without demonstrating truly scalable quantum hardware manufacturing, the impact and benefits of quantum technology will be delayed and limited.”