Native 780 nm all-fiber laser system for quantum sensing

Khawlah AlYahyaei, Xiushan Zhu, Nasser N. Peyghambarian +1 more

Yingjie Ma, Yutong Wang, Xinxiu Zhou +2 more

We developed a fiber-laser-pumped Ti:sapphire laser system designed for quantum precision measurement applications. By employing a 35 W single-frequency 532 nm fiber laser as the pump source, the system delivered continuous-wave output powers of 4.12 W at 770.108 nm (D 1 line, K), 4.72 W at 780.244 nm (D 2 line, Rb), and 5.29 W at 794.982 nm (D 1 line, Rb), thereby fulfilling the requirements for optical pumping and probing of alkali atoms. To enhance frequency stability, saturated absorption spectroscopy was used to lock the laser frequency, resulting in frequency drifts below 1 MHz over two hours. Furthermore, since low-frequency intensity noise (DC-100 Hz) critically affects spin-relaxation-free quantum sensing, we carried out a theoretical analysis which identified the pump laser as the dominant noise source. By implementing feedback control to the pump source as well as an external noise suppression, both methods achieved over 30 dB of intensity noise suppression within the DC-4kHz frequency range. In addition, improved beam pointing stability further reduced noise below 3 Hz. These results collectively demonstrate the system’s strong potential for quantum sensing applications.

Andrei Fedotov, Iuliia Zalesskaia, Petteri Uusimaa

박경득, 이동진, Heedeuk Shin

Yaochen Zhu, Qihui Liu, Xiao Peng +8 more

In this report, we propose a quantum sensing architecture for high-voltage (HV) grid current measurement based on an integrated diamond quantum sensor (DQS). The DQS is installed in the HV line for non-invasive busbar current measurement. An optical fiber composite insulator (OFCI) is employed to deliver 532 nm laser for diamond excitation, 860 nm laser to energize sensing system and 830 nm light for communication between equipment on high-voltage and low-voltage side. The OFCI ensures robust insulation performance while facilitating high-precision, long-distance current measurements. Dual-channel microwave (MW) configuration implemented in the board-level measurement system tracks two resonant frequencies along the nitrogen-vacancy (NV) axis, effectively suppressing temperature drift. This quantum sensing scheme achieves a measurement range of up to 5000 A with an accuracy of 0.15%. This configuration presents a novel approach and reliable system for the practical application of quantum sensors in HV grid monitoring.

Matteo Marchesini, Michelangelo Dondi, Leonardo Rossi +3 more

In this proceeding we present the design and characterization of a relatively simple, compact, and cost-effective laser system for quantum technologies. It operates at 780 nm to work with Rubidium (Rb) atoms, and apart from the frequency locking setup it is entirely based on fiber components. This improves reliability and makes it less complex and more versatile with respect to a free-space system. We also describe our experimental setup, aimed at demonstrating the possibility of confining atoms in hollow-core photonic-crystal fibers (HCPCF), while still being able to keep atoms cold and performing quantum sensing measurements. We finally present our characterization of the system. The measured features (rms relative amplitude noise of 3·10-4at 1 s; linewidths well below 1 MHz; pressure in the vacuum chamber lower9mbar) indeed make our system a suitable candidate for applications in quantum sensors and atom interferometers, which are briefly discussed.