Breakthrough: Tiny Quantum Light Sensor Fits on Silicon Chip

Researchers at the University of Bristol have achieved a significant milestone in quantum technology by developing the world's smallest room temperature quantum light sensor on a silicon chip. The quantum photonic sensor circuit, measuring 80 by 220 micrometres, represents a major advancement in the field of quantum optics.

Professor Jonathan Matthews, the lead researcher and Director of the Quantum Engineering Technology Labs at Bristol, highlighted the versatility of these homodyne detectors in various quantum applications. These sensors can operate at room temperature and have the potential to revolutionize quantum communications, enhance the sensitivity of sensors such as gravitational wave detectors, and even play a crucial role in the development of quantum computers.

The chip's design and characterization were meticulously carried out in-house, with fabrication outsourced to the Leibniz Institute for High Performance Microelectronics (IHP). The use of germanium-based photodiodes and vertically integrated heterojunction bipolar transistors has enabled the sensor to achieve impressive specifications, including a transition frequency of 220 GHz and a breakdown voltage of 1.7 V.

In a groundbreaking development in 2021, the Bristol team demonstrated a significant speed enhancement in quantum light detectors by linking a photonics chip with a separate electronics chip. Now, with the integration of both components into a single chip, the team has further increased the speed by a factor of 10 while reducing the footprint by a factor of 50.

Dr. Giacomo Ferranti, a key researcher on the project, emphasized the importance of sensitivity to quantum noise in measuring quantum light. The team's efforts to make the detector smaller and faster without compromising its sensitivity have paved the way for more accurate measurements of quantum states and enhanced performance in optical sensors.