Fundamental quantum physics and quantum sensing
Research Topic 1: Theory and methology for quantum enhanced sensing
The field of quantum sensing with unprecedented applications in basic science and technology has emerged as a compelling frontier for quantum technologies. Importantly, quantum enhanced sensing can achieve the celebrated Heisenberg limit of measurement precision by exploiting quantum strategies, which acts as a hallmark of scaling improvement over the standard quantum limit that arises from classical uncorrelated measurements. Our group is interested in achieving the advantage of quantum sensing in terms of surpassing the SQL and reaching the Heisenberg limit, by developing novel quantum resources (e.g. quantum criticality, quantum entanglement, quantum chaos etc.) and ultilizing quantum control techinques (e.g. Floquet driving, quantum measurements etc.) to establish ultra-precise measurement methods.
Selected Publications:
lBaiyi Yu, Yaoming Chu, Ralf Betzholz, Shaoliang Zhang, Jianming Cai, Engineering artificial atomic systems of giant electric dipole moment, Physical Review Letters, 132, 073202 (2024).
lYaoming Chu, Shaoliang Zhang, Baiyi Yu, and Jianming Cai, Dynamic framework for criticality-enhanced quantum sensing, Physical Review Letters, 126, 010502 (2021).
lYaoming Chu, Pengcheng Yang, Musang Gong, Min Yu, Baiyi Yu, Martin B. Plenio, Alex Retzker and Jianming Cai, Precise spectroscopy of high-frequency oscillating fields with a single-qubit sensor, Physical Review Applied, 15, 014031 (2021).
lYaoming Chu, Yu Liu, Haibin Liu, and Jianming Cai, Quantum sensing with a single-qubit pseudo-Hermitian system, Physical Review Letters, 124, 020501 (2020).
lPengcheng Yang, Min Yu, Ralf Betzholz, Christian Arenz, Jianming Cai, Complete quantum-state tomography with a local random field, Physical Review Letters, 124, 010405 (2020).
lYu Liu, Jiazhao Tian, Ralf Betzholz, Jianming Cai, Pulsed quantum-state reconstruction of dark systems, Physical Review Letters, 122, 110406 (2019).
Research Topic 2: Bridge fundamental quantum physics and quantum metrology
Quantum sensing can shape our understanding of the world. Investigating the quantum limits of metrology, e.g., in terms of the measurement precision and channel capacity, is possible to yield fundamental insights into its connections to quantum entanglement, geometry, topology, thermodynamics and information theory etc. Furthermore, the quantum Fisher information that is a central quantity of quantum metrology, plays important roles in various fundamental quantum concepts, including macroscopicity, quantum criticality, many-body nonlocality, many-body localization, quantum chaos and so on. We are now working on establishing subtle links between these intriguing concepts and quantum metrology and offering new ways to understand them from the metrological perspective.
Selected Publications:
lMin Yu, Xiangbei Li, Yaoming Chu, Bruno Mera, F Nur Ünal, Pengcheng Yang, Yu Liu, Nathan Goldman, Jianming Cai, Experimental demonstration of topological bounds in quantum metrology, National Science Review, nwae065 (2024).
lYaoming Chu, Xiangbei Li and Jianming Cai, Strong quantum metrological limit from many-body physics, Physical Review Letters, 130,170801(2023).
lYaoming Chu and Jianming Cai, Thermodynamic principle for quantum metrology, Physical Review Letters, 128, 200501 (2022) (Editors' Suggestion).
lMin Yu, Yu Liu, Pengcheng Yang, Musang Gong, Qingyun Cao, Shaoliang Zhang, Haibin Liu, Markus Heyl, Tomoki Ozawa, Nathan Goldman, Jianming Cai, Quantum Fisher information measurement and verification of the quantum Cramér–Rao bound in a solid-state qubit, npj Quantum Information, 8, 56 (2022).
Solid-state quantum control and quantum sensing
The nitrogen-vacancy (NV) center in diamond is a kind of defect center in diamond, which is an isolated single-spin system trapped in diamond. The NV spins exhibits exceeding stability and ultra-long quantum coherence time even at room temperature. The spin states can be fully controlled by microwave radiation and measured by visible laser. These properties make them promising in acting as quantum bits commonly for quantum computing and quantum communication applications. In addition, the spin resonance also shows ultrahigh sensitivities to many other physical parameters, such as magnetic field, electric field, temperature and pressure etc. Our group is interested in studying fundamental physics using NV centers as quantum platform, developing novel quantum sensing protocols such as hybrid sensing to enhance the sensing capabilities, and then applying NV sensing (magnetometry, thermometry) to interdisciplinary research.
Research Topic 1: Advanced quantum control and quantum dynamics
Quantum systems demonstrate fascinating features that are absent in classical phenomena. We are exploring novel concepts in quantum physics and quantum dynamics. Collaborating with theoretical teams within our own group and from research groups worldwide, we utilize NV centers as a quantum platform to explore intriguing quantum phases and quantum matters. Additionally, we work on developing flexible quantum control tools to advance the implementation of quantum technologies.
Selected Publications:
lYaoming Chu, Jianming Cai, A local probe for many-body physics. Nature Physics 19, 933–934 (2023).
lMin Yu, Dongxiao Li, Jingcheng Wang, Yaoming Chu, Pengcheng Yang, Musang Gong, Nathan Goldman and Jianming Cai, Experimental estimation of the quantum Fisher information from randomized measurements, Physical Review Research, 3, 043122 (2022).
lMin Yu, Pengcheng Yang, Musang Gong, Qingyun Cao, Qiuyu Lu, Haibin Liu, Shaoliang Zhang, Martin B Plenio, Fedor Jelezko, Tomoki Ozawa, Nathan Goldman, Jianming Cai, Experimental measurement of the quantum geometric tensor using coupled qubits in diamond, National Science Review, 7, 254 (2020).
lZ.-J. Shu, Yu Liu, Qingyun Cao, Pengcheng Yang, Shaoliang Zhang, Martin B. Plenio, Fedor Jelezko, Jianming Cai, Observation of Floquet-Raman transition in a driven solid-state spin system, Phys. Rev. Lett. 121, 210501 (2018).
lJ.-M. Cai, Alex Retzker, Fedor Jelezko, Martin B. Plenio, A large-scale quantum simulator on diamond surface at room temperature, Nature Physics 9, 168-173 (2013).
Research Topic 2: Novel quantum sensing technology
NV centers have been successfully utilized in sensing applications for measuring magnetic fields, temperature, pressure, and electrical fields, among others. Of these, NV centers exhibit the highest sensitivity to magnetic fields. In our research group, we are focused on enhancing the sensitivity of parameters with weak or no spin response, and further improving the sensitivity of magnetic field measurements. To achieve this, we are exploring novel sensing protocols such as hybrid quantum sensing and intricate pulse design. Through hybrid sensing, we have significantly increased the sensitivity of both temperature and pressure measurements.
Selected publications:
lM. Gong, J. Xu, M. Yu, L. Zhang, Q. Li, N. Wang, and J. Cai, Hybrid Diamond Quantum Sensor with Submicrokelvin Resolution under Ambient Conditions, Phys. Rev. Appl. 21, 024053 (2024).
lN. Wang and J. Cai, Hybrid Quantum Sensing in Diamond, Front. Phys. 12, (2024).
lN. Wang et al., Magnetic Criticality Enhanced Hybrid Nanodiamond Thermometer under Ambient Conditions, Phys. Rev. X 8, 1 (2018).
lJ. Cai, F. Jelezko, and M. B. Plenio, Hybrid Sensors Based on Colour Centres in Diamond and Piezoactive Layers, Nat. Commun. 5, 1 (2014).
Research Topic 3: Applications to interdisciplinary research
In addition to the exceptional quantum properties of NV centers, diamond, the host material for NV centers, provides excellent biocompatibility, the highest thermal conductivity among solids, and stability in extreme conditions. These characteristics make NV centers highly promising for a wide range of applications. Our research group is also exploring the application of NV sensing in multidisciplinary studies, including condensed matter physics, biology, and other fields.
Selected publications:
lQ-Y. Cao, P.-C. Yang, M.-S. Gong, M. Yu, A. Retzker, M.B. Plenio, C. Müller, N. Tomek, B. Naydenov, L.P. McGuinness, F. Jelezko, J.-M. Cai, Protecting quantum spin coherence of nanodiamonds in living cells, Phys. Rev. Applied 13, 024021 (2020).
lHaibin Liu, M. B. Plenio, Jianming Cai, Scheme for detection of single-molecule radical pair reaction using spin in diamond, Phys. Rev. Lett. 118, 200402 (2017).
lC. Müller, X. Kong, J.-M. Cai, K. Melentijevic , A. Stacey, M. Markham, D. Twitchen, J. Isoya, S. Pezzagna, J. Meijer, J.-F. Du , M. Plenio, B. Naydenov, L. P. McGuinness F. Jelezko, Nuclear magnetic resonance spectroscopy and imaging with single spin sensitivity. Nature Communications 5, 4703 (2014).
lA. Ermakova, G. Pramanik, J.-M. Cai, G. Algara-Siller, U. Kaiser, T. Weil, Y.-K. Tzeng , H. C. Chang , L. P. McGuinness, M. B. Plenio, B. Naydenov, and F. Jelezko, Detection of a Few Metallo-Protein Molecules Using Color Centers in Nanodiamonds, Nano Lett. 13 (7), 3305-3309 (2013).