image: The long-range non-reciprocal couplings are shown in the top left. The sensing results compared with those based on exceptional point-based sensor are provided in the top right. The corresponding circuit realization for the reconstructed sensor is provided in the bottom left, and the detection of tiny quantities is shown in bottom right.
Credit: ©Science China Press
This study is led by Dr. Xiangdong Zhang (Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements of Ministry of Education, Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems and Beijing Institute of Technology). The theoretical scheme and derivation were conducted by Dr. Tian Chen, and the experiments were performed by Dr. Deyuan Zou. To break through the sensitivity of the existing sensors, many new physical mechanisms were introduced into the design. A popular way to reach the high sensitivity merges the non-Hermitian exception point into the sensor design. But this upper bound of sensitivity is limited by the order of non-Hermitian degeneracy. How to improve the sensitivity beyond the performance of exceptional point-based sensor becomes a challenge task nowadays.
Chen and Zou, led by the lab director Zhang, sought to determine whether the limit of exceptional point based sessor can be overcome. After an intricate reconstruction around the EP, they found the sensitivity limitation of the exceptional point sensor was surpassed due to the introduction of long-range non-reciprocal couplings.
The team designed those coupling strengths to obey a power-law relationship with chain length. Based on such a construction, the sensitivity of this reconstructed system around the sixth exceptional point was improved by three orders compared to the corresponding order exceptional point-based sensor. “This design is rather simple, yet the sensor effect is enough good” Zhang says.
The researchers also fabricated the circuit sensors designed above and experimentally demonstrated the superior sensitivity in the detection of the tiny physical quantities. At first, the tiny value of the capacitor was determined. Based on the reconstructed sensor, the minimum change of 1pF in the capacitor can be accurately measured. Then, by applying this sensor to measure the displacement between two 75*200mm electrode plates, a variation of 0.75mm in the displacement can be determined exactly.
Zhang said, “These experimental results on the electric circuit illustrate the incredible performance in the detection of tiny physical quantities. This new design can be easily extended to chip-implemented circuit sensor. There are three main advantages in the implementation on the chip, the first thing is the easily configurable components in the realization, the second thing is the enormous reduction of the parasitic effect, and the third thing is the increase operating frequency. In this way, considering three main advantages above, our design in this work displays a feasible prospect to implement a novel ultrasensitive sensor on the chip.
Sensors are of fundamental importance and widely used in modern society, such as in industry and environmental monitoring, biomedical sample ingredient analysis, wireless networks and so on. The authors in this work designed and fabricated corresponding integrated circuit sensors to demonstrate the reconstructed scheme. It paves the way for the development of highly sensitive sensors, which have a wide range of applications in various fields.
See the article:
Ultra-sensitivity in reconstructed exceptional systems
https://doi.org/10.1093/nsr/nwae278
Journal
National Science Review