肖志成教师主页

基本信息 Research interests: Non-Hermitian Physics, Nonreciprocity, Topological Physics, Magnetless Circulators, PT-symmetry. Courses Taught: Circuit Analysis, Digital circuit analysis and design Email: zhichengxiao@hnu.edu.cn Address:  A211, College of Physics and Microelectronics, Hunan University, Changsha 410082, China

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教育背景

教育背景 2015-2021年，德州大学奥斯汀分校，电子工程博士，导师 Prof. Andrea Alù（UT Austin, Ph.D. in Electrical and Computer Engineering） 2012-2014年，戴顿大学，光电子硕士, 导师 Profs. Partha Banerjee, Joseph Haus (University of Dayton, M.S. in Electro-Optics) 2009-2012年，湖南大学，信息与通信工程硕士（Hunan University, M.Eng. in Electrical Engineering） 2005-2009年， 湖南大学，应用物理学 （Hunan Univeresity, B.S. in Applied Physics）

工作履历

工作履历 2015-2021年， 德州大学奥斯汀分校，助教和助研 2020.09-2020.12 Skyworks Solutions, 实习研究员 2012-2013年，戴顿大学，助教

研究领域

学术成果 博士论文-Doctoral DissertationWave Transport in parity-time symmetric, time-varying, and quasi-periodic systems科研论文-Journal Papers[14] J. Liu, Q. Yang, S. Chen, Z. Xiao, S. Wen, and H. Luo, Intrinsic Optical Spatial Differentiation Enabled Quantum Dark-Field Microscopy, Phys. Rev. Lett., 128, 193601 (2022). By solving the Maxwell's equations in Fourier space, we find that the cross-polarized component of the dipole scattering field can be written as the second-order spatial differentiation of the copolarized component. This differential operation can be regarded as intrinsic which naturally arises as consequence of the transversality of electromagnetic fields. By introducing the intrinsic spatial differentiation into heralded single-photon microscopy imaging technique, it makes the structure of pure-phase object clearly visible at low photon level, avoiding any biophysical damages to living cells. Based on the polarization entanglement, the switch between dark-field imaging and bright-field imaging is remotely controlled in the heralding arm. This research enriches both fields of optical analog computing and quantum microscopy, opening a promising route toward a nondestructive imaging of living biological systems.[13] Z. Xiao and Andrea Alù, Tailoring exceptional points in a hybrid PT-symmetric and anti-PT-symmetric scattering system, Nanophotonics, 10, 3723 (2021). (Invited paper)Fano resonances feature an asymmetric line-shape with controllable linewidth, stemming from the interplay between bright and dark resonances. They provide efficient opportunities to shape the scattering lineshape, but they usually lack flexibility and tunability and are hindered by loss in passive systems. Here, we explore a hybrid parity-time (PT) and anti-parity-time (APT) symmetric system supporting unitary scattering features with highly tunable Fano resonances. The PT-APT-symmetric system can be envisioned in nanophotonic and microwave circuit implementations, allowing for real-time control of the scattering lineshape and its underlying singularities. Our study shows the opportunities enabled by non-Hermitian platforms to control scattering lineshapes for a plethora of photonic, electronic, and quantum systems, with potential for high-resolution imaging, switching, sensing, and multiplexing.[12] X. Ni, Z. Xiao, A. B. Khanikaev, A. Alù, Robust multiplexing with topolectrical higher-order Chern insulators, Phys. Rev. Applied., 13, 064031 (2020).We explore an implementation of a higher-order Chern insulator in a topolectrical circuit as a platform to implement robust signal multiplexing. By utilizing basic circuit layouts that realize the required complex hopping between neighboring lattice sites, we demonstrate different topological phases in a three-dimensional topolectrical circuit, including a Wannier-based Chern insulator and a crystalline topological phase. The topological chiral hinge states supported by the circuit are nonreciprocal and avoid propagation to the hinge opposite the excitation. Such an unusual response can be explained in terms of a synthetic gauge field of the circuit lattice, enabling multiplexing inherently robust to defects.[11] Z. Xiao, D. L. Sounas, A. Nagulu, M. Tymchenko, T. Dinc, H. Krishnaswamy, and A. Alù, Role of Synchronization in magnetless nonreciprocal devices based on commutated transmission lines, Phys. Rev. Appl. 13, 064033 (2020).Commutated transmission lines have been recently explored as an interesting way to break Lorentz reciprocity, avoiding any resonant structure, and enabling broad bandwidths with giant isolation combined with lenient requirements on the modulation frequency. The scheme relies on precise synchronization among different switches connected through transmission lines, offering in principle infinite bandwidth. Here, we investigate the effects of realistic switching parameters and synchronization on the device performance, providing interesting physical insights on the operation of these devices. Our research shows that the nonreciprocal response of these systems experiences a linear regression of insertion loss and isolation with respect to the timing error among switches. Remarkably, impedance matching and nonreciprocal phase shifts are immune from synchronization issues, and reasonable levels of synchronization errors still guarantee low insertion loss and good isolation. Our study also provides practical guidelines to envision nonreciprocal devices based on commutated modulation of conductivity, opening interesting opportunities for several fields of technology, including wireless communications, quantum technologies, and photonic circuits.[10] Z. Xiao, H. Li, T. Kottos and A. Alù, Enhanced sensing and nondegraded thermal noise performance based on PT-symmetric electronic circuits with a sixth-order exceptional point. Phys. Rev. Lett. 123, 213901 (2019).An exceptional point (EP) is a non-Hermitian degeneracy where both eigenvalues and their corresponding eigenvectors coalesce. It was recently proposed and demonstrated that such spectral singularity can be utilized for enhanced sensing. Potential drawbacks of EP sensing include both fundamental resolution limit and noise effects that might mask the hypersensitive resonant splitting. Here, we address these issues by proposing a parity-time (PT )-symmetric sensing circuit bearing a sixth-order EP. By employing capacitive coupling channel as a sensing platform, we achieve an enhanced resonance shift proportional to the fourth-order root of the perturbation strength and maintain a high resolution for weak perturbation. Due to the low-pass feature of our circuit, thermal noise is mitigated down to a level comparable to its Hermitian counterpart, despite the presence of highly noisy gain and loss elements. Our EP sensing scheme offers combined enhanced sensitivity, improved resolution and nondegraded thermal noise performance, showing an exciting prospect for next-generation sensing technologies.[9] Z. Xiao, Y. Radi, S. Tretyakov, and A. Alù, Microwave tunneling and robust information transfer based on parity-time-symmetric absorber-emitter Pairs, Research 2019, 10 (2019).Robust signal transfer in the form of electromagnetic waves is of fundamental importance in modern technology, yet its operation is often challenged by unwanted modifications of the channel connecting transmitter and receiver. Parity-time- (PT-) symmetric systems, combining active and passive elements in a balanced form, provide an interesting route in this context. Here, we demonstrate a PT-symmetric microwave system operating in the extreme case in which the channel is shorted through a small reactance, which acts as a nearly impenetrable obstacle, and it is therefore expected to induce large reflections and poor transmission. After placing a gain element behind the obstacle, and a balanced lossy element in front of it, we observe full restoration of information and overall transparency to an external observer, despite the presence of the obstacle. Our theory, simulations, and experiments unambiguously demonstrate stable and robust wave tunneling and information transfer supported by PT symmetry, opening opportunities for efficient communication through channels with dynamic changes, active filtering, and active metamaterial technology.[8] Y. Yu, G. Michetti, M. Pirro, A. Kord, D. Sounas, Z. Xiao, C. Cassella, A. Alù, M. Rinaldi, Radio frequency magnetfree circulators based on spatialtemporal modulation of surface acoustic wave filters, IEEE Trans. Microw. Theory Techn. 67, 4773 (2019).[7] Y. Yu, G. Michetti, A. Kord, M. Pirro, D. Sounas, Z. Xiao, C. Cassella, A. Alù, M. Rinaldi, Highly-linear magnetfree microelectromechanical circulators, IEEE J. Microelectromechanical Systems 28, 933 (2019). [6] X. Zhou, X. Lin, Z. Xiao, T. Low, A. Alù, B. Zhang, H. Sun, Controlling photonic spin Hall effect via exceptional points, Phys. Rev. B 100, 115429 (2019). [5] A. Nagulu, T. Dinc, Z. Xiao, M. Tymchenko, D. L. Sounas, A. Alù, and H. Krishnaswamy, Nonreciprocal Components Based on Switched Transmission Lines, IEEE Transactions on Microwave Theory and Techniques 66, 4706 (2018).[4] A. Kord, D. L. Sounas, Z. Xiao, A. Alù, Broadband cyclic-symmetric magnetless circulators and theoretical bounds on their bandwidth, IEEE Trans. Microw. Theory Techn. 66, 5472 (2018).[3] M. Tang, X. Zhou, Z. Xiao, H. Luo, S. Wen, Switching the direction of spin accumulation in the spin Hall effect of light by adjusting the optical axis of an unixial crystal, Chin. Phys. B 22, 034101 (2013).[2] X. Zhou, Z. Xiao, H. Luo, S. Wen, Experimental observation of the spin Hall effect of light on a nanometal film via weak measurements, Phys. Rev. A 85, 043809 (2012).[1] Z. Xiao, H. Luo, S. Wen, Goos-Hanchen and Imbert-Fedorov shifts of vortex beams at air-left-handed-material interfaces, Phys. Rev. A 85, 053822 (2012).会议论文-Conference Papers[3]  X. Ni,  Z. Xiao, A. B. Khanikaev, A. Alù, A topological higher-order Chern insulator, 2020 Fourteenth International Congress on Artificial Materials for Novel Wave Phenomena – Metamaterials, 2020(Invited Talk)[2]  Z. Xiao, Y. Ra'di, D. Sounas, A. Alù, Parity-time symmetry and exceptional points in Metamaterials, URSI meeting, San Diego, 2019-7-1(Invited Talk)[1] Z. Xiao, Y. Ra'di, A. Alù, Parity-time symmetric wave tunneling and teleportation using dispersive negative impedance converters, URSI meeting, Colorado, Boulder, 2018-01-05 (Invited Talk)

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