Ultra-stable laser driver paves the way to commercial quantum sensors

In recent years, engineers at Microchip Technology’s Caldicot site in South Wales have been developing quantum sensors.

Such sensors use the fundamental properties of atoms to detect subtle changes in the surrounding environment. Atomic magnetometers and gyroscopes could offer extremely high sensitivity and accuracy, with applications from detecting hidden corrosion or buried infrastructure to navigation without GPS.

The challenge

Such systems use a tiny laser called a VCSEL to control the energy state of atoms inside a sealed chamber, putting them into a known, sensitive state. Once in this controlled state, changes in a magnetic field or rotation alter their atomic behaviour, which can be measured to reveal information about directional changes or the makeup of the surrounding environment.

To reliably control the atoms’ energy state, the laser must emit light at the right wavelength to interact with the atoms’ energy levels, with extremely high requirements on stability.

Microchip had developed an integrated electronics system that powers and controls this VCSEL laser. To deliver the precise laser wavelength, its R&D team sought to stabilise the input current and temperature, both of which impact the wavelength. 

But they needed to know for sure that the emitted wavelength met the required stability levels for these quantum technologies before they could continue with product development. “This was work we simply couldn’t do on our own,” says Tracy Wotherspoon, Design Development Lead at Microchip Technology Caldicot Ltd. “We understand the electronics, but we don’t have this level of laser light measurement capability in-house.”

The solution

Through a Measurement for Quantum (M4Q) project, Microchip worked with NPL to validate its laser system. Microchip supplied several versions of its laser electronics, representing different combinations of hardware design and control firmware. 

NPL tested various combinations of hardware and firmware using optical techniques that measure how the laser interacts with atoms. By passing laser light through a cell containing caesium atoms, the team could observe how small variations in current or temperature affected the laser’s behaviour – providing a sensitive test of performance.

This allowed the team to compare different design options side-by-side. It identified which combinations delivered the best stability, and validated that the optimal combination did indeed meet Microchip’s high stability requirements. 

The impact

The project provided Microchip with an independent validation that its laser driver performance is suitable for use in quantum systems.

It also gave the team a deeper understanding of the system, helping inform future development, including which firmware version to focus on, and identifying an improved voltage regulator that has led to a big improvement in laser stability. 

“NPL’s independent testing and validation provided us with confidence in our product, and greatly reduced our technical risk as we move forward with the development of high-quality quantum sensors,” says Wotherspoon. 

Whilst this is just one piece of the puzzle, the work represents a key step forward for Microchip in developing commercially viable atomic magnetometers and gyroscopes, as well as chip-scale atomic clocks. These frontier technologies have huge potential for navigation and sensing in aerospace, defence, infrastructure monitoring, and security. Quantum is a fast-evolving industry, and this could represent a big commercial opportunity, with some analyses suggesting quantum sensors could be a $1.2bn market by 2032.

Beyond the technical outcomes, the collaboration is proving valuable for the reputation of the Caldicot quantum team both within Microchip Technology, and beyond. That, in turn, is strengthening the Welsh site’s position as a centre of expertise in quantum-enabled electronics, and supporting the UK’s strategic ambitions in quantum technologies.