As a special order of electronic correlation induced by spatial modulation, the charge density wave(CDW) phenomena in condensed matters attract enormous research interests. Here, using scanning-tunneling microscopy in...As a special order of electronic correlation induced by spatial modulation, the charge density wave(CDW) phenomena in condensed matters attract enormous research interests. Here, using scanning-tunneling microscopy in various temperatures, we discover a hidden incommensurate stripe-like CDW order besides the(■) CDW phase at low-temperature of 4 K in the epitaxial monolayer 1T-VSe_(2) film. Combining the variable-temperature angle-resolved photoemission spectroscopic(ARPES) measurements, we discover a two-step transition of an anisotropic CDW gap structure that consists of two parts △_(1) and△_(2). The gap part ?1 that closes around ~ 150 K is accompanied with the vanish of the(√7×√3) CDW phase. While another momentum-dependent gap part △_(2) can survive up to ~ 340 K, and is suggested to the result of the incommensurate CDW phase. This two-step transition with anisotropic gap opening and the resulted evolution in ARPES spectra are corroborated by our theoretical calculation based on a phenomenological form for the self-energy containing a two-gap structure △_(1) +△_(2), which suggests different forming mechanisms between the(√7×√3) and the incommensurate CDW phases. Our findings provide significant information and deep understandings on the CDW phases in monolayer 1T-VSe_(2) film as a two-dimensional(2D) material.展开更多
We propose to achieve nonreciprocal quantum control of photons in a quadratic optomechanical(QOM)system based on directional nonlinear interactions.We show that by optically pumping the QOM system in one side,the effe...We propose to achieve nonreciprocal quantum control of photons in a quadratic optomechanical(QOM)system based on directional nonlinear interactions.We show that by optically pumping the QOM system in one side,the effective QOM coupling can be enhanced significantly in that side,but not for the other side.This,contrary to the intuitive picture,allows the emergence of a nonreciprocal photon blockade in such optomechanical devices with weak single-photon QOM coupling.Our proposal opens up the prospect of exploring and utilizing quantum nonreciprocal optomechanics,with applications ranging from single-photon nonreciprocal devices to on-chip chiral quantum engineering.展开更多
Stimulated emission and absorption are two fundamental processes of light–matter interaction, and the coefficients of the two processes should be equal. However, we will describe a generic method to realize the signi...Stimulated emission and absorption are two fundamental processes of light–matter interaction, and the coefficients of the two processes should be equal. However, we will describe a generic method to realize the significant difference between the stimulated emission and absorption coefficients of two nondegenerate energy levels, which we refer to as a nonreciprocal transition. As a simple implementation, a cyclic three-level atom system, comprising two nondegenerate energy levels and one auxiliary energy level, is employed to show a nonreciprocal transition via a combination of synthetic magnetism and reservoir engineering. Moreover, a single-photon nonreciprocal transporter is proposed using two one-dimensional semi-infinite coupled-resonator waveguides connected by an atom with nonreciprocal transition effect. Our work opens up a route to design atom-mediated nonreciprocal devices in a wide range of physical systems.展开更多
In this paper, we propose a single-photon router via the use of a four-level atom system coupled with two one-dimensional coupled-resonator waveguides. A single photon can be directed from one quantum channel into ano...In this paper, we propose a single-photon router via the use of a four-level atom system coupled with two one-dimensional coupled-resonator waveguides. A single photon can be directed from one quantum channel into another by atomic spontaneous emission. The coherent resonance and the photonic bound states lead to the perfect reflection appearing in the incident channel.The fidelity of the atom is related to the magnitude of the coupling strength and can reach unit when the coupling strength matches g_a = g_b. This shows that the transfer of a single photon into another quantum channel has no influence on the fidelity at special points.展开更多
This study highlights the theoretical investigation of quantum coherence in mechanical oscillators and its transfer between the cavity and mechanical modes of an optomechanical system comprising an optical cavity and ...This study highlights the theoretical investigation of quantum coherence in mechanical oscillators and its transfer between the cavity and mechanical modes of an optomechanical system comprising an optical cavity and two mechanical oscillators that,in this study,were simultaneously coupled to the optical cavity at different optomechanical coupling strengths.The quantum coherence transfer between the optical and mechanical modes is found to depend strongly on the relative magnitude of the two optomechanical couplings.The laser power,decay rates of the cavity and mechanical oscillators,environmental temperature,and frequency of the mechanical oscillator are observed to significantly influence the investigated quantum coherences.Moreover,quantum coherence generation in the optomechanical system is restricted by the system's stability condition,which helps sustain high and stable quantum coherence in the optomechanical system.展开更多
We describe an optomechanical ratchet scheme to realize nonreciprocal transmission of a light field, which is based on the bias of the optical cavity’s frequency spectrum caused by mechanical ratchet interactions. Th...We describe an optomechanical ratchet scheme to realize nonreciprocal transmission of a light field, which is based on the bias of the optical cavity’s frequency spectrum caused by mechanical ratchet interactions. This approach to break the time-reversal symmetry of light propagation is universally valid in various optomechanical systems with ratchet-oscillator structures. We discuss specifically the implementation of an on-chip Casimir-ratchet optomechanical protocol and demonstrate the optical nonreciprocity with an extremely high isolation ratio and flexible controllability, which does not require external additional optical engineering. Our study opens a door for manipulating flexibly light propagation by using mechanical ratchet resonators, and has potential applications in the on-chip integration of nonreciprocal devices and harness of lateral Casimir forces.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 92165205, 11790311, 12004172, 11774152, 11604366, and 11634007)the National Key Research and Development Program of China (Grant Nos. 2018YFA0306800 and 2016YFA0300401)+1 种基金the Program of High-Level Entrepreneurial and Innovative Talents Introduction of Jiangsu Province, the Jiangsu Planned Projects for Postdoctoral Research Funds (Grant No. 2020Z172)the Natural Science Foundation of Jiangsu Province, China (Grant No. BK 20160397)。
文摘As a special order of electronic correlation induced by spatial modulation, the charge density wave(CDW) phenomena in condensed matters attract enormous research interests. Here, using scanning-tunneling microscopy in various temperatures, we discover a hidden incommensurate stripe-like CDW order besides the(■) CDW phase at low-temperature of 4 K in the epitaxial monolayer 1T-VSe_(2) film. Combining the variable-temperature angle-resolved photoemission spectroscopic(ARPES) measurements, we discover a two-step transition of an anisotropic CDW gap structure that consists of two parts △_(1) and△_(2). The gap part ?1 that closes around ~ 150 K is accompanied with the vanish of the(√7×√3) CDW phase. While another momentum-dependent gap part △_(2) can survive up to ~ 340 K, and is suggested to the result of the incommensurate CDW phase. This two-step transition with anisotropic gap opening and the resulted evolution in ARPES spectra are corroborated by our theoretical calculation based on a phenomenological form for the self-energy containing a two-gap structure △_(1) +△_(2), which suggests different forming mechanisms between the(√7×√3) and the incommensurate CDW phases. Our findings provide significant information and deep understandings on the CDW phases in monolayer 1T-VSe_(2) film as a two-dimensional(2D) material.
基金Natural Science Foundation of Jiangxi Province(20192ACB21002)National Natural Science Foundation of China(11604096,11904013,11847165,11474087,11774086,11935006,11775190)。
文摘We propose to achieve nonreciprocal quantum control of photons in a quadratic optomechanical(QOM)system based on directional nonlinear interactions.We show that by optically pumping the QOM system in one side,the effective QOM coupling can be enhanced significantly in that side,but not for the other side.This,contrary to the intuitive picture,allows the emergence of a nonreciprocal photon blockade in such optomechanical devices with weak single-photon QOM coupling.Our proposal opens up the prospect of exploring and utilizing quantum nonreciprocal optomechanics,with applications ranging from single-photon nonreciprocal devices to on-chip chiral quantum engineering.
基金National Natural Science Foundation of China(12064010,11904013,11847165,11775190)Natural Science Foundation of Jiangxi Province(20192ACB21002)+2 种基金National Basic Research Program of China(973 Program)(2014CB921401)Tsinghua University Initiative Scientific Research ProgramTsinghua National Laboratory for Information Science and Technology(TNList)Crossdiscipline Foundation。
文摘Stimulated emission and absorption are two fundamental processes of light–matter interaction, and the coefficients of the two processes should be equal. However, we will describe a generic method to realize the significant difference between the stimulated emission and absorption coefficients of two nondegenerate energy levels, which we refer to as a nonreciprocal transition. As a simple implementation, a cyclic three-level atom system, comprising two nondegenerate energy levels and one auxiliary energy level, is employed to show a nonreciprocal transition via a combination of synthetic magnetism and reservoir engineering. Moreover, a single-photon nonreciprocal transporter is proposed using two one-dimensional semi-infinite coupled-resonator waveguides connected by an atom with nonreciprocal transition effect. Our work opens up a route to design atom-mediated nonreciprocal devices in a wide range of physical systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.11674253,61471356,and 11365009)
文摘In this paper, we propose a single-photon router via the use of a four-level atom system coupled with two one-dimensional coupled-resonator waveguides. A single photon can be directed from one quantum channel into another by atomic spontaneous emission. The coherent resonance and the photonic bound states lead to the perfect reflection appearing in the incident channel.The fidelity of the atom is related to the magnitude of the coupling strength and can reach unit when the coupling strength matches g_a = g_b. This shows that the transfer of a single photon into another quantum channel has no influence on the fidelity at special points.
基金supported by the National Natural Science Foundation of China(Grant Nos.11565014,11775190,11375093,and11775035)the Natural Science Foundation of Jiangxi Province(Grant No.20171BAB201015)+1 种基金the Science and Technology of Jiangxi Province(Grant No.20171BAB212006)the Education Bureau of Jiangxi Province(Grant No.JJ160503)
文摘This study highlights the theoretical investigation of quantum coherence in mechanical oscillators and its transfer between the cavity and mechanical modes of an optomechanical system comprising an optical cavity and two mechanical oscillators that,in this study,were simultaneously coupled to the optical cavity at different optomechanical coupling strengths.The quantum coherence transfer between the optical and mechanical modes is found to depend strongly on the relative magnitude of the two optomechanical couplings.The laser power,decay rates of the cavity and mechanical oscillators,environmental temperature,and frequency of the mechanical oscillator are observed to significantly influence the investigated quantum coherences.Moreover,quantum coherence generation in the optomechanical system is restricted by the system's stability condition,which helps sustain high and stable quantum coherence in the optomechanical system.
基金supported by the National Natural Science Foundation of China(Grant No.12065008)the Key Project of Youth Science Foundation of Jiangxi Province(Grant No.20192ACBL21001)+2 种基金the Outstanding Youth Project of Jiangxi Province(Grant No.20192BCBL23007)supported by the National Natural Science Foundation of China(Grant No.11775190)supported by the National Natural Science Foundation of China(Grant No.11775035)。
文摘We describe an optomechanical ratchet scheme to realize nonreciprocal transmission of a light field, which is based on the bias of the optical cavity’s frequency spectrum caused by mechanical ratchet interactions. This approach to break the time-reversal symmetry of light propagation is universally valid in various optomechanical systems with ratchet-oscillator structures. We discuss specifically the implementation of an on-chip Casimir-ratchet optomechanical protocol and demonstrate the optical nonreciprocity with an extremely high isolation ratio and flexible controllability, which does not require external additional optical engineering. Our study opens a door for manipulating flexibly light propagation by using mechanical ratchet resonators, and has potential applications in the on-chip integration of nonreciprocal devices and harness of lateral Casimir forces.