Article
Physics, Multidisciplinary
Xin Yang, Jiawen Li, Yifei Ding, Mengwei Xu, Xue-Feng Zhu, Jie Zhu
Summary: The transient parity-time (PT) symmetry in electronics is demonstrated in this study. By equivalent circuit transformation according to the switching states of electronic systems, the PT symmetry is revealed. Using the phasor method and Laplace transformation, the hidden PT-symmetric Hamiltonian in the switching oscillation is derived, which is characterized by free oscillation modes. The spectral and dynamic properties of the PT electronic structure demonstrate the phase transition and eigenmode orthogonality. Importantly, the observed transient PT symmetry enables optimal switching oscillation suppression induced by exceptional points, showing the significance of PT symmetry in electronic systems with temporary responses. The study paves the way for breakthroughs in PT symmetry theory and has essential applications such as anti-interference in switch-mode electronics.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Stavros Komineas
Summary: A system of interacting spins under the influence of spin-polarized currents is described using a complex functional or a non-Hermitian (NH) Hamiltonian. The dynamics of two exchange-coupled spins on the Bloch sphere are studied, and an exceptional point in the nonlinear system is identified when currents lead to PT symmetry. The nonlinear system exhibits bistable behavior and can show stable oscillating motion or relax to an equilibrium point, similar to synchronized spin-torque oscillators.
Article
Multidisciplinary Sciences
Guoqiang Xu, Xue Zhou, Shuihua Yang, Jing Wu, Cheng-Wei Qiu
Summary: This study presents a method for generating quantized bulk quadrupole moments in fluid heat transport and observing quadrupole topological phases. The experimental results show that both the real- and imaginary-valued bands in thermal systems exhibit hierarchical features of bulk, gapped edge, and in-gap corner states.
NATURE COMMUNICATIONS
(2023)
Article
Optics
Hyun Gyu Song, Minho Choi, Kie Young Woo, Chung Hyun Park, Yong-Hoon Cho
Summary: Researchers demonstrated room-temperature polaritonic parity-time-reversal symmetry by coupling exciton-polariton modes to one another in a six-fold symmetric microcavity with loss modulation. This direct coupling led to a phase transition from unbroken to broken symmetry, revealing the lowest threshold of polariton condensates in non-Hermitian degeneracies despite increasing loss.
Article
Multidisciplinary Sciences
Geng-Li Zhang, Di Liu, Man-Hong Yung
Summary: The study proposes an extendable method to simulate non-Hermitian systems and study exceptional points using quantum circuits. By breaking the parity-time symmetry, the system is inherently PT broken, and a sample circuit is implemented in a quantum programming framework to demonstrate the phase transition at the exceptional point. With the scalable and flexible nature of quantum circuits, the model is capable of simulating large-scale systems with higher-order exceptional points.
SCIENTIFIC REPORTS
(2021)
Article
Optics
Dimitrios Chatzidimitriou, Alexandros Pitilakis, Traianos Yioultsis, Emmanouil E. Kriezis
Summary: The study explores the breaking of reciprocity in non-Hermitian coupled photonic waveguides through saturable absorption and the presence of exceptional points, providing important performance metrics for nonreciprocal operation of such devices with potential for high-speed applications.
Article
Physics, Multidisciplinary
Shruti Dogra, Artem A. Melnikov, Gheorghe Sorin Paraoanu
Summary: By simulating the evolution under non-Hermitian Hamiltonians on a superconducting quantum processor, this study observed the PT-symmetry breaking phase transition at exceptional points, obtained the critical exponent, and demonstrated that this transition is related to a loss of state distinguishability.
COMMUNICATIONS PHYSICS
(2021)
Article
Optics
Kaustubh S. Agarwal, Yogesh N. Joglekar
Summary: The study obtained the PT threshold for a one-dimensional, finite Kitaev chain and identified a rich phase diagram for the threshold, which can be qualitatively understood in relation to the band structure of the Hermitian Kitaev model. The findings include a re-entrant PT-symmetric phase bounded by second-order exceptional point contours for an even chain with zero on-site potential.
Article
Physics, Multidisciplinary
Chao Liang, Yuanjiang Tang, An-Ning Xu, Yong-Chun Liu
Summary: In this study, we experimentally observe EPs and enhance magnetic field sensing in thermal atomic ensembles. We use the rich energy levels of atoms to construct effective decays and propose an optical polarization rotation measurement scheme for detecting resonance peak splitting, which has an advantage over conventional transmission measurement schemes. Additionally, our system allows flexible adjustment of the effective coupling strength and decay rates, enabling tunable EP positions and expanding the measurement range.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Sebae Park, Dongjin Lee, Kyungdeuk Park, Heedeuk Shin, Youngsun Choi, Jae Woong Yoon
Summary: In this study, an optical anti-parity-time (APT) symmetric system was created using a conventional fiber to demonstrate photonic APT-symmetric effects, such as energy-difference conservation and synchronized power oscillation. The results provide a theoretical and experimental framework linking non-Hermitian physics with technologically important nonlinear fiberoptic interactions.
PHYSICAL REVIEW LETTERS
(2021)
Article
Optics
Max Ehrhardt, Matthias Heinrich, Alexander Szameit
Summary: The ability of indistinguishable particles to interfere with one another is a fundamental principle in quantum mechanics. In this study, the researchers experimentally demonstrate the tunability of coincidence statistics for boson pairs, from full suppression to enhancement, by selecting an appropriate observation basis. This finding could have important implications for manipulating multi-particle quantum states and using non-Hermitian settings as functional elements in quantum simulation.
Article
Optics
Hao Ding, Qizhuang Cen, Kun Xu, Ming Li, Yitang Dai
Summary: In recent years, parity-time (PT) symmetry in optoelectronic systems has been widely studied for its potential applications in lasers, sensors, topological networks, and other fields. This paper proposes a time-division multiplexed pulsed optoelectronic oscillator (OEO) to study the dynamics of a PT symmetry system. The experimental results demonstrate that pulsed OEO is an excellent platform to explore the dynamics of PT symmetry and other non-Hermitian Hamiltonian systems.
PHOTONICS RESEARCH
(2022)
Article
Physics, Multidisciplinary
Dongdong Hao, Lin Wang, Xingda Lu, Xuzhen Cao, Suotang Jia, Ying Hu, Yanhong Xiao
Summary: Recent experimental advances in creating dissipative couplings provide a new route for engineering exotic lattice systems and exploring topological dissipation. Using a spatial lattice of atomic spin waves, we experimentally realize a dissipative version of the Su-Schrieffer-Heeger (SSH) model. The dissipative spectrum of the topological lattices shows edge modes within a dissipative gap. This work opens up the possibility of realizing non-Hermitian topological quantum optics through dissipative couplings.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Guo-Qiang Zhang, Zhen Chen, Wei Xiong, Chi-Hang Lam, J. Q. You
Summary: We studied the parity-symmetry-breaking quantum phase transition in a cavity magnonic system driven by a parametric field, which can exhibit a rich phase diagram including parity-symmetric, parity-symmetry-broken, and bistable phases with appropriate parameters. Beyond a critical threshold of drive strength, the system undergoes a first- or second-order nonequilibrium QPT from the parity-symmetric phase with microscopic excitations to the parity-symmetrybroken phase with macroscopic excitations, depending on the system parameters. Our work offers an alternative way to engineer the QPT in a hybrid quantum system containing a spin ensemble in ferri- or ferromagnetic materials with strong exchange interactions.
Article
Physics, Applied
L. Lin, Y. S. Tang, L. Huang, W. J. Zhai, G. Z. Zhou, J. H. Zhang, M. F. Liu, G. Y. Li, X. Y. Li, Z. B. Yan, J. -m. Liu
Summary: In this study, clear evidence for linear magneto-electric (ME) coupling in the CoSe2O5 compound was provided through systematic investigations on magnetic, dielectric, and ferroelectric properties. The findings revealed the magnetism-driven ferroelectricity and the observed off diagonal linear ME effect is consistent with theoretical predictions. This study has important implications for further exploration of intriguing phenomena and physics in this compound.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Inorganic & Nuclear
Qiaoling Chen, Longbing Shang, Chong-Geng Ma, Chang-Kui Duan
Summary: First-principles calculations based on density functional theory were used to study the electronic structure, excited-state Jahn-Teller distortion, and photoluminescence of tetrahedral coordinated Mn2+ in solids. The results showed that the emission energy and color can be affected by the nephelauxetic effect and crystal field strength. The Jahn-Teller distortion of the excited states was found to be dominated by the angular distortion of the [MnL4] moiety.
INORGANIC CHEMISTRY
(2022)
Article
Materials Science, Multidisciplinary
Longbing Shang, Qiaoling Chen, Weiguo Jing, Chong-Geng Ma, Chang-Kui Duan, Jiangfeng Du
Summary: Defect centers in solid-state materials have been widely studied for their potential applications in quantum information science. In this work, the feasibility of using tetrahedral d(2) and octahedral d(3) transition metal ions as spin qubits is analyzed using density functional theory. The results show that some of these systems meet the requirements for forming the desired electronic structures and spin-selective transitions.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Physics, Multidisciplinary
Peiran Yin, Rui Li, Chengjiang Yin, Xiangyu Xu, Xiang Bian, Han Xie, Chang-Kui Duan, Pu Huang, Jian-hua He, Jiangfeng Du
Summary: In this study, the chameleon theory as a candidate explanation for dark energy is ruled out by experimental tests, providing decisive conclusions and demonstrating the reliability of laboratory experiments for uncovering the nature of dark energy in the future.
Article
Physics, Multidisciplinary
Yue Fu, Wenquan Liu, Xiangyu Ye, Ya Wang, Chengjie Zhang, Chang-Kui Duan, Xing Rong, Jiangfeng Du
Summary: This experimental investigation demonstrates the existence of quantum correlations in a two-qutrit spin system at room temperature using a single nitrogen-vacancy center in diamond. The study reveals the presence of quantum entanglement and nonclassical correlations beyond entanglement in the qutrit case. These findings highlight the potential of NV centers as a multiqutrit system for quantum information tasks and offer a powerful experimental platform for studying high-dimensional quantum systems in the future.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Applied
Jiliang Yang, Jian Wang, Wenda Fan, Yangbo Zhang, Changkui Duan, Guangchong Hu, Gabriele G. de Boo, Brett C. Johnson, Jeffrey C. McCallum, Sven Rogge, Chunming Yin, Jiangfeng Du
Summary: Single rare-earth ions in solids have great potential for quantum applications, but their linewidths are often broadened due to perturbations associated with the detection methods. By studying the spectral broadening of a single Er3+ ion in a Si nanotransistor, we found that charge fluctuations are likely to be the dominant broadening source.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Applied
Zhi Cheng, Xiangyu Ye, Jiandong Wu, Pei Yu, Cheng-Jie Wang, Mengqi Wang, Changkui Duan, Ya Wang, Fazhan Shi, Changlin Tian, Hongwei Chen, Pengfei Wang, Jiangfen Du
Summary: Nanoscale sensing and imaging of electromagnetic field can be achieved by utilizing the forbidden magnetic dipole transition of a single shallow nitrogen-vacancy center in diamond. The detection of rf electric fields at frequencies ranging from 13.85 MHz to 2.02 GHz is successfully demonstrated, with a sensitivity of 265 V cm-1 Hz-1/2 for amplitude measurement and a standard deviation of 0.2 degrees for phase measurement. The potential applications of such nanoscale sensor in science and technology are discussed.
PHYSICAL REVIEW APPLIED
(2023)
Article
Chemistry, Physical
Mingzhe Liu, Hei-Yui Kai, Anjun Huang, Chang-Kui Duan, Ka-Leung Wong, Peter A. Tanner
Summary: First-principles calculations were conducted to investigate the doping of bismuth and iron in the lattices of BaAl12O19 (BAO) and CaAl12O19 (CAO). Experimental data for the optical spectra of CAO were provided to support the calculation results. The presence of trace impurities in undoped CAO samples, such as Mn4+, was observed to contribute to luminescence bands. The emission wavelengths of around 810 nm in CAO were found to be associated with Fe3+ and Bi3+ dopants.
CHEMISTRY OF MATERIALS
(2023)
Article
Optics
Jun Wen, Jing Gao, Guisheng Jiang, Xiaoxiao Huang, Qiang Wang, Chenlong Wei, Lixin Ning, Chang-Kui Duan
Summary: Theoretical studies were conducted to investigate the thermodynamic stabilities and luminescent properties of defects and lanthanide ions in BaZrSi3O9, aiming to gain a better understanding of the luminescence mechanisms in undoped and lanthanide-doped BaZrSi3O9.
JOURNAL OF LUMINESCENCE
(2023)
Article
Chemistry, Physical
Mingzhe Liu, Chang-Kui Duan, Ruijie Hao, Min Yin
Summary: A variety of halide perovskites doped with ns2 ions have been studied. First-principles calculations were performed on Cs2SnCl6 and Cs2HfCl6 to explore self-trapped excitons, defects, and luminescent centers. The results provide a consistent understanding of the experimental phenomena and reveal differences between Cs2SnCl6 and Cs2(Hf/Zr)Cl6, which can benefit the design and optimization of metal halide perovskites.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Quantum Science & Technology
Jianpei Geng, Tetyana Shalomayeva, Mariia Gryzlova, Amlan Mukherjee, Santo Santonocito, Dzhavid Dzhavadzade, Durga Bhaktavatsala Rao Dasari, Hiromitsu Kato, Rainer Stoehr, Andrej Denisenko, Norikazu Mizuochi, Jorg Wrachtrup
Summary: This study investigates the stabilization of negatively charged nitrogen-vacancy (NV-) centers in phosphorus-doped diamond at liquid helium temperatures. It demonstrates that photoionization of phosphorus donors enhances the conversion of NV0 to NV- and stabilizes the charge state without the need for an additional repump laser.
NPJ QUANTUM INFORMATION
(2023)
Article
Physics, Multidisciplinary
Han Xie, Yanan Li, Rui Li, Yinchun Leng, Yiming Chen, Lei Wang, Dingjiang Long, Xiang Bian, Chang-Kui Duan, Peiran Yin, Pu Huang, Jiangfeng Du
Summary: By utilizing an engineering conductive geometry scheme, we effectively reduce the mechanical dissipation of a diamagnetically levitated oscillator made of pyrolytic graphite, improving its levitation capability. Through experimental demonstration, we show that the specially designed conductive geometry significantly reduces eddy current damping, with a higher reduction factor for denser engraving patterns. Under high vacuum and room temperature conditions, we reduce eddy current damping by a factor of 50. This work presents a new approach to achieve ultralow mechanical dissipation and strong levitation capability in diamagnetically levitated oscillators, providing a candidate platform for studying a broad range of fundamental physics.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Haoming Xu, Weiguo Jing, Mingzhe Liu, Min Yin, Chang-Kui Duan
Summary: The abnormal self-reduction of trivalent lanthanides in borates, particularly in SrB4O7, has been reported for many years, but only an explanatory description has been provided. Through calculations of formation energies in SrB4O7, we offer an explanation for the mechanisms behind the self-reduction phenomenon. Additionally, we present the trends of the binding energies of divalent lanthanides, which align well with and support the results obtained by extrapolating experimental data using the semiempirical chemical shift model. Our findings demonstrate that calculations conducted using the supercell method and projector augmented wave pseudopotentials can effectively interpret reduction and charge-transfer phenomena, and serve as a basis for the design of lanthanide-doped optical materials.
Article
Materials Science, Multidisciplinary
Zhaoyang Feng, Chang-Kui Duan
Summary: In this study, first-principles calculations were used to investigate the luminescence properties of four different ternary oxide materials, namely (Sr/Ca)Sb2O6, (Sr/Ca)2Sb2O7, (Sr/Ca)SnO3, and (Sr/Ca)Ga2O4, doped with bismuth ions. The effects of bismuth doping on the materials' luminescence properties were analyzed by studying intrinsic defects and self-trapped holes. The transitions associated with bismuth ions in different materials were also identified. The insights gained from this study are important for understanding the luminescence mechanisms of insulating bismuth-doped ternary oxides.
Article
Optics
Yang Wu, Yunhan Wang, Xiangyu Ye, Wenquan Liu, Chang-Kui Duan, Ya Wang, Xing Rong, Jiangfeng Du
Summary: The knot topology in gapped non-Hermitian systems is comprehensively studied using the universal dilation method with a long-coherence-time nitrogen-vacancy center in a purified diamond. The braiding patterns of energy bands and the eigenstate topology are revealed, and the global biorthogonal Berry phase related to the eigenstate topology is successfully observed, demonstrating the topological invariance in the non-Hermitian system.
Article
Optics
Maimaitiyiming Tusun, Wei Cheng, Zihua Chai, Yang Wu, Ya Wang, Xing Rong, Jiangfeng Du
Summary: Investigating the boundary between quantum mechanical description and classical realistic view is fundamentally important. The Leggett-Garg inequality serves as a criterion to distinguish between quantum and classical systems, and it has been used to prove the existence of macroscopic superposition states. In this study, an experimental violation of the Leggett-Garg inequality in a three-level system using a nitrogen-vacancy center in diamond is presented, providing evidence beyond the Ltiders bound with a high level of confidence.
