Recently, the research team led by Academician Guo Guangcan, including Sun Fangwen's group and the group of Zou Chongwen from the National Synchrotron Radiation Laboratory/School of Nuclear Science and Technology, collaborated to achieve optically controlled local insulator-metal phase transition in vanadium dioxide (VO2) thin films. This enabled the reconfigurable shaping of micro-nano current pathways and demonstrated its application in solid-state spin quantum control. Zhang Shaochun, CTO of Guosheng Quantum, was deeply involved in this work. The results were published on August 29 under the title "Reconfigurable photothermal doping filament for selective spin manipulation and addressing" in the Proceedings of the National Academy of Sciences (PNAS).

Figure 1 Schematic diagram of the experimental setup

The control and detection of micro-nano scale currents are important means to achieve information and energy transmission. This is a core technology in current integrated electronics and information science and is widely studied and applied in frontier fundamental fields such as quantum science. With increasing demands for information processing, micro-nano electronic devices based on traditional semiconductor processes are becoming more complex and power-consuming. Reconfigurable electronic devices offer a new solution for the development of next-generation information technology. Unlike traditional single-function electronic devices, they can dynamically change their functional characteristics according to task requirements, with the potential to achieve more functions without increasing the number or structural complexity of integrated electronic devices.

Sun Fangwen's group and Zou Chongwen's group have long conducted interdisciplinary cooperation, carrying out research on the development of reconfigurable quantum devices and quantum sensing applications. They used strongly correlated vanadium oxide materials to fabricate brain-like neuron structures and achieved quantum imaging of VO2 artificial neuron devices based on diamond color center spin sensing (Sci.Adv.9, eadg9376(2023)).

Figure 2 Schematic diagram of writing the optically controlled current pathway

In this work, researchers proposed a "photothermal doping" technique. By scanning a focused light beam and utilizing its photothermal effect, they triggered a transient insulator-metal phase transition in the VO2 thin film, forming a localized "photothermal doping" micro-region (similar to semiconductor ion implantation doping). This enabled reconfigurable writing of arbitrarily shaped current pathways at the micron scale. This method maps optical field control information onto the spatial distribution of current pathways, showing flexible real-time control over parameters such as current position, direction, and width, achieving arbitrary curved current shapes like an "S" shape. The researchers used this reconfigurable circuit device for DC and microwave signal transmission. The current generated localized electromagnetic signals to pump the diamond color center spin quantum system, realizing coherent quantum state control such as Rabi oscillations and Ramsey fringes. Further, by arbitrarily controlling the current shape combined with the magnetic field gradient generated by the current, selective control of solid-state spin arrays at different spatial positions was achieved, demonstrating spatial addressing capability.

Figure 3 Sample structure and schematic of the "photothermal doping" micro-region

Reconfigurable electronic devices based on optically controlled currents greatly enhance the flexibility of micro-nano scale current control. Subsequently, researchers will further improve optical field control capabilities, enhance the reliability of reconfigurable current pathway control, and increase current conduction capacity to achieve chip-scale arbitrarily reconfigurable currents. Utilizing the on-site repeat editing capability of optically controlled circuits, multifunctional, highly flexible, and efficient integrated chips can be realized, playing an important role in artificial intelligence, next-generation information technology, and other fields, providing support for scalable quantum control and detection devices.

Figure 4 Selective microwave control of diamond color center arrays using reconfigurable optically controlled currents

The first author of this paper is Liu Zhiwei, a PhD student at the Quantum Network Anhui Provincial Key Laboratory. The corresponding authors are Associate Researcher Chen Xiangdong, Researcher Zou Chongwen, and Professor Sun Fangwen. Academician Guo Guangcan also participated in this research. This work was supported by the 2030 Major Project for Science and Technology Innovation, the Youth Team Project in the field of basic research supported by the Chinese Academy of Sciences, the National Natural Science Foundation, Anhui Province Key R&D Program, and other projects.

Zhang Shaochun, CTO of Guosheng Quantum, stated: "The 'photothermal doping' technology achieves dynamic reconfiguration of current pathways through optical field control, enabling real-time adjustment of the spatial distribution of electromagnetic signals. This allows precise selection and manipulation of NV color centers without frequent hardware modifications, breaking the limitations of fixed traditional micro-nano circuit structures. It is expected to accelerate the practical application of quantum technology in intelligent sensing, integrated chips, and other fields."

Paper link: https://www.pnas.org/doi/abs/10.1073/pnas.2507587122