Auckland and US Researchers Demonstrate Chip-Based Optical Frequency Comb

University of Auckland and United States researchers demonstrated a chip-based optical frequency comb designed to support portable atomic clocks and precision measurement systems, The Quantum Insider reported. Researchers used two lasers positioned an octave apart to generate evenly spaced light frequencies, overcoming stabilization challenges that previously kept the tools restricted to laboratories.

The system performs three core tasks on a single chip: generating precise optical frequencies, producing low-noise millimetre-wave signals, and executing integrated optical clock readout. These capabilities address the control difficulties that historically hindered deployable atomic timekeeping, according to Grégory Moille of the University of Maryland.

Miniaturizing Optical Frequency Combs For Portable Navigation

Optical frequency combs function as light rulers by producing millions of perfectly spaced frequencies of light to measure time, distance, and chemical signals with extreme accuracy. Traditional systems rely on a single laser that cascades outward to cover a wide spectrum, requiring bulky equipment and expensive lab setups. By inverting this approach and starting with two lasers placed an octave apart at opposite ends of the spectrum, the new architecture automatically fills in the intervening frequencies.

The technology stems from work that began in 2021 when Miro Erkintalo, head of the Department of Physics at the University of Auckland and a researcher at the Dodd-Walls Centre for Photonic and Quantum Technologies, used student modeling to predict that two laser beams launched into a chip-scale ring could generate a new frequency comb type. In 2024, that theoretical concept transitioned into a practical lab demonstration as Auckland researchers teamed up with scientists Kartik Srinivasan and Grégory Moille from the US National Institute of Science and Technology and the University of Maryland.

Merging Quantum Computations With Tweezer Clocks

In a parallel development published in the journal Nature, a Caltech team led by Professor of Physics Manuel Endres built a device that merges state-of-the-art atomic clocks with quantum computers to achieve extreme measurement precision. While atomic clocks use quantum mechanics to measure time and quantum computers use it to perform calculations, the Caltech researchers integrated both systems at their interface, as reported by Caltech.

The Caltech team built upon their previous work with tweezer clocks, which use laser tweezers to control arrays of neutral strontium atoms. To maximize precision, the researchers demonstrated that atoms in a tweezer clock array can be entangled, a quantum phenomenon where particles link without direct contact. The study was co-led by graduate students Richard Bing-Shiun Tsai and Xiangkai Sun of Caltech, alongside former Caltech postdoctoral scholar Ran Finkelstein, who is now stationed at Tel Aviv University.

Submitting Provisional Patents For Commercial Deployment

The University of Auckland and United States research team submitted a provisional patent application covering aspects of the chip-based optical frequency comb work. Reducing the size, weight, power, and cost of optical frequency combs aims to move the technology from academic laboratories into consumer applications, including positioning systems independent of GPS satellite signals and underground mineral mapping.

Concurrently, the Caltech research received funding from the Army Research Office, the National Science Foundation via the Institute for Quantum Information and Matter, the Defense Advanced Research Projects Agency, and the U.S. Department of Energy through its Quantum Systems Accelerator. Future work for the Caltech group involves reducing system errors to push atomic clocks closer to theoretical limits of precision for applications such as detecting gravitational waves and probing Albert Einstein’s general theory of relativity.