A model of an irreversible quantum Carnot heat engine with heat resistance,internal irreversibility and heat leakage and many non-interacting harmonic oscillators is established in this paper. Based on the quantum mas...A model of an irreversible quantum Carnot heat engine with heat resistance,internal irreversibility and heat leakage and many non-interacting harmonic oscillators is established in this paper. Based on the quantum master equation and semi-group approach,equations of some important performance parameters,such as power output,efficiency,exergy loss rate and ecological function for the irreversible quantum Carnot heat engine are derived. The optimal ecological performance of the heat engine in the classical limit is analyzed with numerical examples. Effects of internal irreversibility and heat leakage on the ecological performance are discussed. A performance comparison of the quantum heat engine under maximum ecological function and maximum power conditions is also performed.展开更多
We study the Klein-Gordon oscillators in non-commutative （NC） phase space. We find that the Klein-Gordon oscillators in NC space and NC phase-space have a similar behaviour to the dynamics of a particle in commutati...We study the Klein-Gordon oscillators in non-commutative （NC） phase space. We find that the Klein-Gordon oscillators in NC space and NC phase-space have a similar behaviour to the dynamics of a particle in commutative space moving in a uniform magnetic field. By solving the Klein-Gordon equation in NC phase space, we obtain the energy levels of the Klein-Gordon oscillators, where the additional terms related to the space-space and momentum-momentum non-commutativity are given explicitly.展开更多
The energy balance equations in the Classical Statistical Energy Analysis (CSEA) are modified by the equations of power flow among the thtee serial coupled oscinators. The modified equations include not only the direc...The energy balance equations in the Classical Statistical Energy Analysis (CSEA) are modified by the equations of power flow among the thtee serial coupled oscinators. The modified equations include not only the direct power flow, but also the indirect power flow. The parameters in the modified equations can be expressed by those in the classical equations when the accuracy of the predicted results is able to satisfy the needs for ellgineering.展开更多
We present a 1.5μm continuous-wave （CW） single-frequency intracavity singly resonant optical parametric oscillator （SRO） based on periodically poled lithium niobate （PPLN）. The SRO is placed inside the ring cav...We present a 1.5μm continuous-wave （CW） single-frequency intracavity singly resonant optical parametric oscillator （SRO） based on periodically poled lithium niobate （PPLN）. The SRO is placed inside the ring cavity of a single-frequency 1.06μm Nd：YVO4 laser pumped by a laser diode. The device delivers a maximum single-frequency output power of 310 mW at a resonant signal wavelength of 1.57 μm. The signal wave could be tuned from 1.57 to 1.59 μm by temperature tuning of PPLN crystal over the range of 130 - 170℃.展开更多
An all-solid-state mid-infrared optical parametric oscillator with wide tunability by using two identical multi-grating periodically poled 5-mol.-% MgO-doped lithium niobate cascaded is reported. The pump laser is an ...An all-solid-state mid-infrared optical parametric oscillator with wide tunability by using two identical multi-grating periodically poled 5-mol.-% MgO-doped lithium niobate cascaded is reported. The pump laser is an acousto-optically Q-switched Nd：YAG laser with 150-ns pulse width at repetition rate of 10 kHz. Wide tunability from 2.789 to 4.957μm at the idler wavelength is achieved by varying the temperature from 40 to 200 ~C and translating the grating periods from 26 to 31 μm with a step of 0.5μm. When the incident pump average power is 8.15 W, the maximum idler output average power is 2.23 W at 3.344 μm and the optic-optic conversion efficiency is about 27.4%.展开更多
A high-average-power,high-repetition-rate dual signal optical parametric oscillator based on periodically poled MgO-doped lithium niobate（PPMgLN） with a phase-reversed grating is reported.The pump laser is an acoust...A high-average-power,high-repetition-rate dual signal optical parametric oscillator based on periodically poled MgO-doped lithium niobate（PPMgLN） with a phase-reversed grating is reported.The pump laser is an acousto-optically Q-switched Nd：YVO_4 laser with a maximum average power of 7.6 W.When the repetition rate is 50 kHz and the pulse width of the pump source is 23 ns,the maximum average dual signal output power is about 1.9 W,leading to a conversion efficiency of 25%.Over a 30-min interval,the instability of the signal power measured is less than 0.5%.展开更多
The theoretical analysis and experimental results of the wavelength tunability of a tandem optical parametric oscillator （TOPO） based on a single nonlinear crystal are presented.TOPO is a configuration wherein the s...The theoretical analysis and experimental results of the wavelength tunability of a tandem optical parametric oscillator （TOPO） based on a single nonlinear crystal are presented.TOPO is a configuration wherein the signal laser is used as a pump laser to generate secondary optical parametric oscillator （OPO）.The cascaded parametric interactions are achieved synchronously in a single-grating-period MgO doped periodically poled lithium niobate （PPMgOLN）.Tunable multiple-wavelength mid-infrared （mid-IR） lasers are obtained by changing the temperature of the crystal.When the PPMgOLN crystal with a grating period of 31.2 μm is operated at 148 ℃,the dual OPOs generate an identical mid-IR laser of 2.83 μm.The secondary OPO transforms into an optical parametric amplifier,in which different frequency mixing from the signal laser results in the amplification of the idler laser in the first OPO.TOPO is a useful configuration for multiple laser output,broad tuning range,and high-efficiency mid-IR lasers.展开更多
Background： Self-sustained oscillations are a ubiquitous and vital phenomenon in living systems. From primitive single-cellular bacteria to the most sophisticated organisms, periodicities have been observed in a broa...Background： Self-sustained oscillations are a ubiquitous and vital phenomenon in living systems. From primitive single-cellular bacteria to the most sophisticated organisms, periodicities have been observed in a broad spectrum of biological processes such as neuron firing, heart beats, cell cycles, circadian rhythms, etc. Defects in these oscillators can cause diseases from insomnia to cancer. Elucidating their fundamental mechanisms is of great significance to diseases, and yet challenging, due to the complexity and diversity of these oscillators. Results： Approaches in quantitative systems biology and synthetic biology have been most effective by simplifying the systems to contain only the most essential regulators. Here, we will review major progress that has been made in understanding biological oscillators using these approaches. The quantitative systems biology approach allows for identification of the essential components of an oscillator in an endogenous system. The synthetic biology approach makes use of the knowledge to design the simplest, de novo oscillators in both live cells and cell-free systems. These synthetic oscillators are tractable to further detailed analysis and manipulations. Conclusion： With the recent development of biological and computational tools, both approaches have made significant achievements.展开更多
Optically levitated oscillators in high vacuum have excellent environmental isolation and low mass compared with conventional solid-state sensors,which makes them suitable for ultrasensitive force detection.The force ...Optically levitated oscillators in high vacuum have excellent environmental isolation and low mass compared with conventional solid-state sensors,which makes them suitable for ultrasensitive force detection.The force resolution usually scales with the measurement bandwidth,which represents the ultimate detection capability of the system under ideal conditions if sufficient time is provided for measurement.However,considering the stability of a real system,a method based on the Allan variance is more reliable to evaluate the actual force detection performance.In this study,a levitated optomechanical system with a force detection sensitivity of 6.33±1.62 zN/Hz^(1/2)was demonstrated.And for the first time,the Allan variance was introduced to evaluate the system stability due to the force sensitivity fluctuations.The force detection resolution of 166.40±55.48 yN was reached at the optimal measurement time of 2751 s.The system demonstrated in this work has the best force detection performance in both sensitivity and resolution that have been reported so far for optically levitated particles.The reported high-sensitivity force detection system is an excellent candidate for the exploration of new physics such as fifth force searching,high-frequency gravitational waves detection,dark matter research and so on.展开更多
The chimera states underlying many realistic dynamical processes have attracted ample attention in the area of dynamical systems.Here, we generalize the Kuramoto model with nonlocal coupling incorporating higher-order...The chimera states underlying many realistic dynamical processes have attracted ample attention in the area of dynamical systems.Here, we generalize the Kuramoto model with nonlocal coupling incorporating higher-order interactions encoded with simplicial complexes.Previous works have shown that higher-order interactions promote coherent states.However, we uncover the fact that the introduced higher-order couplings can significantly enhance the emergence of the incoherent state.Remarkably, we identify that the chimera states arise as a result of multi-attractors in dynamic states.Importantly, we review that the increasing higher-order interactions can significantly shape the emergent probability of chimera states.All the observed results can be well described in terms of the dimension reduction method.This study is a step forward in highlighting the importance of nonlocal higher-order couplings, which might provide control strategies for the occurrence of spatial-temporal patterns in networked systems.展开更多
We demonstrate radiation-pressure-driven mechanical oscillations from high optical quality factor silica microdisk resonators on chip. Mechanical quality factors of 3520 in air and 12540 in vacuum for the fundamental ...We demonstrate radiation-pressure-driven mechanical oscillations from high optical quality factor silica microdisk resonators on chip. Mechanical quality factors of 3520 in air and 12540 in vacuum for the fundamental radial breathing modes are obtained from 73 μm-diarneter silica microdisks with mechanical frequencies of -51 MHz. The measured mechanical oscillation threshold powers for the input light are determined to be 62.5 μW in air and down to 26.6 μW in vacuum.展开更多
Coupled metronomes serve as a paradigmatic model for exploring the collective behaviors of com- plex dynamical systems, as well as a classical setup for classroom demonstrations of synchronization phenomena. Whereas p...Coupled metronomes serve as a paradigmatic model for exploring the collective behaviors of com- plex dynamical systems, as well as a classical setup for classroom demonstrations of synchronization phenomena. Whereas previous studies of metronome synchronization have been concentrating on symmetric coupling schemes, here we consider the asymmetric case by adopting the scheme of layered metronomes. Specifically, we place two metronomes on each layer, and couple two layers by placing one on top of the other. By varying the initial conditions of the metronomes and adjusting the friction between the two layers, a variety of synchronous patterns are observed in experiment, including the splay synchronization （SS） state, the generalized splay synchronization （GSS） state, the anti-phase synchronization （APS） state, the in-phase delay synchronization （IPDS） state, and the in-phase syn- chronization （IPS） state. In particular, the IPDS state, in which the metronomes on each layer are synchronized in phase but are of a constant phase delay to metronomes on the other layer, is observed for the first time. In addition, a new technique based on audio signals is proposed for pattern detection, which is more convenient and easier to apply than the existing acquisition techniques. Furthermore, a theoretical model is developed to explain the experimental observations, and is employed to explore the dynamical properties of the patterns, including the basin distributions and the pattern transitions. Our study sheds new lights on the collective behaviors of coupled metronomes, and the developed setup can be used in the classroom for demonstration purposes.展开更多
In this paper, we reported both the experimental demonstration and theoretical analysis of a Raman fiber laser based on a master oscillator–power amplifier configuration. The Raman fiber laser adopted the dual-wavele...In this paper, we reported both the experimental demonstration and theoretical analysis of a Raman fiber laser based on a master oscillator–power amplifier configuration. The Raman fiber laser adopted the dual-wavelength bidirectional pumping configuration, utilizing 976 nm laser diodes and 1018 nm fiber lasers as the pump sources. A 60-m-long25/400 μm ytterbium-doped fiber was used to convert the power from 1070 to 1124 nm, realizing a maximum power output of 3.7 kW with a 3 dB spectral width of 6.8 nm. Moreover, we developed a multi-frequency model taking into consideration the Raman gain spectrum and amplified spontaneous emission. The calculated spectral broadening of both the forward and backward laser was in good agreement with the experimental results. Finally, a 1.5 kW, 1183 nm second-order Raman fiber laser was further experimentally demonstrated by the addition of a 70-m-long germaniumdoped passive fiber.展开更多
In the theory of physical information, the physical phenomena of electromagnetism, quantum mechanics and gravity can be described by means of the action as information enclosed in four dimensional structures with osci...In the theory of physical information, the physical phenomena of electromagnetism, quantum mechanics and gravity can be described by means of the action as information enclosed in four dimensional structures with oscillator properties, under the conditions of the Hamilton principle. The present report shows that it is also possible to simulate the behaviour of the mass under these conditions. As a result, among other things, the statements are obtained that the mass is stored virtual action;the rest frame of elementary objects and the inertia of matter are caused by the action stored in the mass oscillators.展开更多
This work summarizes the structure and operating features of a high-performance 3-stage dual-delay-path (DDP) voltage-controlled ring oscillator (VCRO) with self-biased delay cells for Phase-Locked Loop (PLL) structur...This work summarizes the structure and operating features of a high-performance 3-stage dual-delay-path (DDP) voltage-controlled ring oscillator (VCRO) with self-biased delay cells for Phase-Locked Loop (PLL) structurebased clock generation and digital system driving. For a voltage supply V<sub>DD</sub> = 1.8 V, the resulting set of performance parameters include power consumption P<sub><sub></sub>DC</sub> = 4.68 mW and phase noise PN@1MHz = -107.8 dBc/Hz. From the trade-off involving P<sub>DC</sub> and PN, a system level high performance is obtained considering a reference figure-of-merit ( FoM = -224 dBc/Hz ). Implemented at schematic level by applying CMOS-based technology (UMC L180), the proposed VCRO was designed at Cadence environment and optimized at MunEDA WiCkeD tool.展开更多
The traditional simulations may occasionally turn out to be challenging for the quantum dynamics, particularly those governed by the nonlinear Hamiltonians. In this work, we introduce a nonstandard iterative technique...The traditional simulations may occasionally turn out to be challenging for the quantum dynamics, particularly those governed by the nonlinear Hamiltonians. In this work, we introduce a nonstandard iterative technique where the Liouville space is briefly expanded with an additional (virtual) space only within ultrashort subintervals. This tremendously reduces the cost of time-consuming calculations. We implement our technique for an example of a charged particle in both harmonic and anharmonic potentials. The temporal evolutions of the probability for the particle being in the ground state are obtained numerically and compared to the analytical solutions. We further discuss the physics insight of this technique based on a thought-experiment. Successive processes intrinsically “hitchhiking” via virtual space in discrete ultrashort time duration, are the hallmark of our technique. We believe that this technique has potential for solving numerous problems which often pose a challenge when using the traditional approach based on time-ordered exponentials.展开更多
Mutual synchronization is a ubiquitous phenomenon that exists in various natural systems. The individual participants in this process can be modeled as oscillators, which interact by discrete pulses. In this paper, we...Mutual synchronization is a ubiquitous phenomenon that exists in various natural systems. The individual participants in this process can be modeled as oscillators, which interact by discrete pulses. In this paper, we analyze the synchronization condition of two- and multi-oscillators system, and propose a linear pulse-coupled oscillators model. We prove that the proposed model can achieve synchronization for almost all conditions. Numerical simulations are also included to investigate how different model parameters affect the synchronization. We also discuss the implementation of the model as a new approach for time synchronization in wireless sensor networks.展开更多
We demonstrate a tunable optical parametric oscillator in a periodically poled congruently grown lithium tantalite whispering gallery mode resonator. The resonator is mechanically polished to millimeter size, and the ...We demonstrate a tunable optical parametric oscillator in a periodically poled congruently grown lithium tantalite whispering gallery mode resonator. The resonator is mechanically polished to millimeter size, and the quality factor is approximately 107 at 1064 nm. Our experiments show that this kind of resonator is capable of reaching a very low threshold and having a wide tuning range. Combined with its narrow resonant linewidth,it is potentially used as a compact, widely tunable, and narrow-linewidth infrared to mid-infrared laser source.展开更多
基金Supported by the National Natural Science Foundation of China (Grant No. 50846040)Program for New Century Excellent Talents in University (Grant No. NCET-04-1006)the Foundation for the Author of National Excellent Doctoral Dissertation of P. R. China (Grant No. 200136)
文摘A model of an irreversible quantum Carnot heat engine with heat resistance,internal irreversibility and heat leakage and many non-interacting harmonic oscillators is established in this paper. Based on the quantum master equation and semi-group approach,equations of some important performance parameters,such as power output,efficiency,exergy loss rate and ecological function for the irreversible quantum Carnot heat engine are derived. The optimal ecological performance of the heat engine in the classical limit is analyzed with numerical examples. Effects of internal irreversibility and heat leakage on the ecological performance are discussed. A performance comparison of the quantum heat engine under maximum ecological function and maximum power conditions is also performed.
基金National Natural Science Foundation of China (10575026, 10665001, 10447005)Natural Science Foundation of Zhejiang Province, China (Y607437)Natural Science Foundation of Education Bureau of Shaanxi Province, China (07JK207,06JK326)
文摘We study the Klein-Gordon oscillators in non-commutative （NC） phase space. We find that the Klein-Gordon oscillators in NC space and NC phase-space have a similar behaviour to the dynamics of a particle in commutative space moving in a uniform magnetic field. By solving the Klein-Gordon equation in NC phase space, we obtain the energy levels of the Klein-Gordon oscillators, where the additional terms related to the space-space and momentum-momentum non-commutativity are given explicitly.
文摘The energy balance equations in the Classical Statistical Energy Analysis (CSEA) are modified by the equations of power flow among the thtee serial coupled oscinators. The modified equations include not only the direct power flow, but also the indirect power flow. The parameters in the modified equations can be expressed by those in the classical equations when the accuracy of the predicted results is able to satisfy the needs for ellgineering.
基金supported by the National Natural Science Foundation of China (No. 60527003, 60608011, and60878003)the National Key Basic Research Program of China (No. 2007CB316501)Shanxi Province Young Science Foundation (No. 2006021003)
文摘We present a 1.5μm continuous-wave （CW） single-frequency intracavity singly resonant optical parametric oscillator （SRO） based on periodically poled lithium niobate （PPLN）. The SRO is placed inside the ring cavity of a single-frequency 1.06μm Nd：YVO4 laser pumped by a laser diode. The device delivers a maximum single-frequency output power of 310 mW at a resonant signal wavelength of 1.57 μm. The signal wave could be tuned from 1.57 to 1.59 μm by temperature tuning of PPLN crystal over the range of 130 - 170℃.
基金supported by the Scientific Research Starting Foundation for Returned Overseas Chinese Scholars Ministry of Education,China
文摘An all-solid-state mid-infrared optical parametric oscillator with wide tunability by using two identical multi-grating periodically poled 5-mol.-% MgO-doped lithium niobate cascaded is reported. The pump laser is an acousto-optically Q-switched Nd：YAG laser with 150-ns pulse width at repetition rate of 10 kHz. Wide tunability from 2.789 to 4.957μm at the idler wavelength is achieved by varying the temperature from 40 to 200 ~C and translating the grating periods from 26 to 31 μm with a step of 0.5μm. When the incident pump average power is 8.15 W, the maximum idler output average power is 2.23 W at 3.344 μm and the optic-optic conversion efficiency is about 27.4%.
基金supported in part by the National Natural Science Foundation of China(No.50875074)the Program for Innovative Research Team of Hefei University of Technology+1 种基金the Key Project of Chinese Ministry of Education(No.108073)the Doctoral Special Supporting Foundation of Hefei University of Technology (No.GDBJ2008-026).
文摘A high-average-power,high-repetition-rate dual signal optical parametric oscillator based on periodically poled MgO-doped lithium niobate（PPMgLN） with a phase-reversed grating is reported.The pump laser is an acousto-optically Q-switched Nd：YVO_4 laser with a maximum average power of 7.6 W.When the repetition rate is 50 kHz and the pulse width of the pump source is 23 ns,the maximum average dual signal output power is about 1.9 W,leading to a conversion efficiency of 25%.Over a 30-min interval,the instability of the signal power measured is less than 0.5%.
文摘The theoretical analysis and experimental results of the wavelength tunability of a tandem optical parametric oscillator （TOPO） based on a single nonlinear crystal are presented.TOPO is a configuration wherein the signal laser is used as a pump laser to generate secondary optical parametric oscillator （OPO）.The cascaded parametric interactions are achieved synchronously in a single-grating-period MgO doped periodically poled lithium niobate （PPMgOLN）.Tunable multiple-wavelength mid-infrared （mid-IR） lasers are obtained by changing the temperature of the crystal.When the PPMgOLN crystal with a grating period of 31.2 μm is operated at 148 ℃,the dual OPOs generate an identical mid-IR laser of 2.83 μm.The secondary OPO transforms into an optical parametric amplifier,in which different frequency mixing from the signal laser results in the amplification of the idler laser in the first OPO.TOPO is a useful configuration for multiple laser output,broad tuning range,and high-efficiency mid-IR lasers.
文摘Background： Self-sustained oscillations are a ubiquitous and vital phenomenon in living systems. From primitive single-cellular bacteria to the most sophisticated organisms, periodicities have been observed in a broad spectrum of biological processes such as neuron firing, heart beats, cell cycles, circadian rhythms, etc. Defects in these oscillators can cause diseases from insomnia to cancer. Elucidating their fundamental mechanisms is of great significance to diseases, and yet challenging, due to the complexity and diversity of these oscillators. Results： Approaches in quantitative systems biology and synthetic biology have been most effective by simplifying the systems to contain only the most essential regulators. Here, we will review major progress that has been made in understanding biological oscillators using these approaches. The quantitative systems biology approach allows for identification of the essential components of an oscillator in an endogenous system. The synthetic biology approach makes use of the knowledge to design the simplest, de novo oscillators in both live cells and cell-free systems. These synthetic oscillators are tractable to further detailed analysis and manipulations. Conclusion： With the recent development of biological and computational tools, both approaches have made significant achievements.
基金supported by grants from the National Natural Science Foundation of China(62005248,62075193)Major Project of Natural Science Foundation of Zhejiang Province(LD22F050002)+2 种基金Major Scientific Research Project of Zhejiang Lab(2019MB0AD01,2021MB0AL02,2022MB0AL02)the Fundamental Research Funds for the Central Universities,China(2016XZZX00401 and 2018FZA5002)the National Program for Special Support of Top-Notch Young Professionals(W02070390),China.
文摘Optically levitated oscillators in high vacuum have excellent environmental isolation and low mass compared with conventional solid-state sensors,which makes them suitable for ultrasensitive force detection.The force resolution usually scales with the measurement bandwidth,which represents the ultimate detection capability of the system under ideal conditions if sufficient time is provided for measurement.However,considering the stability of a real system,a method based on the Allan variance is more reliable to evaluate the actual force detection performance.In this study,a levitated optomechanical system with a force detection sensitivity of 6.33±1.62 zN/Hz^(1/2)was demonstrated.And for the first time,the Allan variance was introduced to evaluate the system stability due to the force sensitivity fluctuations.The force detection resolution of 166.40±55.48 yN was reached at the optimal measurement time of 2751 s.The system demonstrated in this work has the best force detection performance in both sensitivity and resolution that have been reported so far for optically levitated particles.The reported high-sensitivity force detection system is an excellent candidate for the exploration of new physics such as fifth force searching,high-frequency gravitational waves detection,dark matter research and so on.
基金Project supported by the National Natural Science Foundation of China (Grants Nos.12375031 and 11905068)the Natural Science Foundation of Fujian Province, China (Grant No.2023J01113)the Scientific Research Funds of Huaqiao University (Grant No.ZQN-810)。
文摘The chimera states underlying many realistic dynamical processes have attracted ample attention in the area of dynamical systems.Here, we generalize the Kuramoto model with nonlocal coupling incorporating higher-order interactions encoded with simplicial complexes.Previous works have shown that higher-order interactions promote coherent states.However, we uncover the fact that the introduced higher-order couplings can significantly enhance the emergence of the incoherent state.Remarkably, we identify that the chimera states arise as a result of multi-attractors in dynamic states.Importantly, we review that the increasing higher-order interactions can significantly shape the emergent probability of chimera states.All the observed results can be well described in terms of the dimension reduction method.This study is a step forward in highlighting the importance of nonlocal higher-order couplings, which might provide control strategies for the occurrence of spatial-temporal patterns in networked systems.
基金supported by the National Basic Research Program of China(Grant Nos.2012CB921804 and 2011CBA00205)the National Natural Science Foundation of China(Grant Nos.61435007,11104137 and 11321063)
文摘We demonstrate radiation-pressure-driven mechanical oscillations from high optical quality factor silica microdisk resonators on chip. Mechanical quality factors of 3520 in air and 12540 in vacuum for the fundamental radial breathing modes are obtained from 73 μm-diarneter silica microdisks with mechanical frequencies of -51 MHz. The measured mechanical oscillation threshold powers for the input light are determined to be 62.5 μW in air and down to 26.6 μW in vacuum.
基金This work was supported by the National Natural Science Foundation of China under Grant No. 11375109, and also by the Fundamental Research Funds for the Central Uni- versities under Grant No. GK201601001.
文摘Coupled metronomes serve as a paradigmatic model for exploring the collective behaviors of com- plex dynamical systems, as well as a classical setup for classroom demonstrations of synchronization phenomena. Whereas previous studies of metronome synchronization have been concentrating on symmetric coupling schemes, here we consider the asymmetric case by adopting the scheme of layered metronomes. Specifically, we place two metronomes on each layer, and couple two layers by placing one on top of the other. By varying the initial conditions of the metronomes and adjusting the friction between the two layers, a variety of synchronous patterns are observed in experiment, including the splay synchronization （SS） state, the generalized splay synchronization （GSS） state, the anti-phase synchronization （APS） state, the in-phase delay synchronization （IPDS） state, and the in-phase syn- chronization （IPS） state. In particular, the IPDS state, in which the metronomes on each layer are synchronized in phase but are of a constant phase delay to metronomes on the other layer, is observed for the first time. In addition, a new technique based on audio signals is proposed for pattern detection, which is more convenient and easier to apply than the existing acquisition techniques. Furthermore, a theoretical model is developed to explain the experimental observations, and is employed to explore the dynamical properties of the patterns, including the basin distributions and the pattern transitions. Our study sheds new lights on the collective behaviors of coupled metronomes, and the developed setup can be used in the classroom for demonstration purposes.
基金supported in part by the National Natural Science Foundation of China (Nos. 61675114 and 61875103)the Tsinghua University Initiative Scientific Research Program (No. 20151080709)
文摘In this paper, we reported both the experimental demonstration and theoretical analysis of a Raman fiber laser based on a master oscillator–power amplifier configuration. The Raman fiber laser adopted the dual-wavelength bidirectional pumping configuration, utilizing 976 nm laser diodes and 1018 nm fiber lasers as the pump sources. A 60-m-long25/400 μm ytterbium-doped fiber was used to convert the power from 1070 to 1124 nm, realizing a maximum power output of 3.7 kW with a 3 dB spectral width of 6.8 nm. Moreover, we developed a multi-frequency model taking into consideration the Raman gain spectrum and amplified spontaneous emission. The calculated spectral broadening of both the forward and backward laser was in good agreement with the experimental results. Finally, a 1.5 kW, 1183 nm second-order Raman fiber laser was further experimentally demonstrated by the addition of a 70-m-long germaniumdoped passive fiber.
文摘In the theory of physical information, the physical phenomena of electromagnetism, quantum mechanics and gravity can be described by means of the action as information enclosed in four dimensional structures with oscillator properties, under the conditions of the Hamilton principle. The present report shows that it is also possible to simulate the behaviour of the mass under these conditions. As a result, among other things, the statements are obtained that the mass is stored virtual action;the rest frame of elementary objects and the inertia of matter are caused by the action stored in the mass oscillators.
文摘This work summarizes the structure and operating features of a high-performance 3-stage dual-delay-path (DDP) voltage-controlled ring oscillator (VCRO) with self-biased delay cells for Phase-Locked Loop (PLL) structurebased clock generation and digital system driving. For a voltage supply V<sub>DD</sub> = 1.8 V, the resulting set of performance parameters include power consumption P<sub><sub></sub>DC</sub> = 4.68 mW and phase noise PN@1MHz = -107.8 dBc/Hz. From the trade-off involving P<sub>DC</sub> and PN, a system level high performance is obtained considering a reference figure-of-merit ( FoM = -224 dBc/Hz ). Implemented at schematic level by applying CMOS-based technology (UMC L180), the proposed VCRO was designed at Cadence environment and optimized at MunEDA WiCkeD tool.
文摘The traditional simulations may occasionally turn out to be challenging for the quantum dynamics, particularly those governed by the nonlinear Hamiltonians. In this work, we introduce a nonstandard iterative technique where the Liouville space is briefly expanded with an additional (virtual) space only within ultrashort subintervals. This tremendously reduces the cost of time-consuming calculations. We implement our technique for an example of a charged particle in both harmonic and anharmonic potentials. The temporal evolutions of the probability for the particle being in the ground state are obtained numerically and compared to the analytical solutions. We further discuss the physics insight of this technique based on a thought-experiment. Successive processes intrinsically “hitchhiking” via virtual space in discrete ultrashort time duration, are the hallmark of our technique. We believe that this technique has potential for solving numerous problems which often pose a challenge when using the traditional approach based on time-ordered exponentials.
文摘Mutual synchronization is a ubiquitous phenomenon that exists in various natural systems. The individual participants in this process can be modeled as oscillators, which interact by discrete pulses. In this paper, we analyze the synchronization condition of two- and multi-oscillators system, and propose a linear pulse-coupled oscillators model. We prove that the proposed model can achieve synchronization for almost all conditions. Numerical simulations are also included to investigate how different model parameters affect the synchronization. We also discuss the implementation of the model as a new approach for time synchronization in wireless sensor networks.
基金supported by the International Science and Technology Cooperation Program of China (ISTCP) (No.2014DFT50230)the National Key Scientific Instrument and Equipment Development Project (No.2011YQ030127)
文摘We demonstrate a tunable optical parametric oscillator in a periodically poled congruently grown lithium tantalite whispering gallery mode resonator. The resonator is mechanically polished to millimeter size, and the quality factor is approximately 107 at 1064 nm. Our experiments show that this kind of resonator is capable of reaching a very low threshold and having a wide tuning range. Combined with its narrow resonant linewidth,it is potentially used as a compact, widely tunable, and narrow-linewidth infrared to mid-infrared laser source.
