Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectificatio...Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectification performance.To address this issue,we developed a thermal rectification structure comprising a current-biased graphene-coated silicon carbide(SiC)substrate paired with another graphene-coated SiC substrate separated by a nanoscale vacuum gap.A current-biased graphene sheet generates nonreciprocal effect that actively modulates radiative energy transfer.Our theoretical framework demonstrates that the current-biased graphene achieves a high thermal diode efficiency even under a modest temperature difference.Remarkably,the thermal diode efficiency exceeds 0.8 at a temperature difference of just 100 K(between 300 K and 400 K).These findings highlight the synergistic enhancement from graphene coatings and current biasing,providing a viable strategy for nanoscale thermal management applications.展开更多
The nonreciprocity of energy transfer is constructed in a nonlinear asymmetric oscillator system that comprises two nonlinear oscillators with different parameters placed between two identical linear oscillators.The s...The nonreciprocity of energy transfer is constructed in a nonlinear asymmetric oscillator system that comprises two nonlinear oscillators with different parameters placed between two identical linear oscillators.The slow-flow equation of the system is derived by the complexification-averaging method.The semi-analytical solutions to this equation are obtained by the least squares method,which are compared with the numerical solutions obtained by the Runge-Kutta method.The distribution of the average energy in the system is studied under periodic and chaotic vibration states,and the energy transfer along two opposite directions is compared.The effect of the excitation amplitude on the nonreciprocity of the system producing the periodic responses is analyzed,where a three-stage energy transfer phenomenon is observed.In the first stage,the energy transfer along the two opposite directions is approximately equal,whereas in the second stage,the asymmetric energy transfer is observed.The energy transfer is also asymmetric in the third stage,but the direction is reversed compared with the second stage.Moreover,the excitation amplitude for exciting the bifurcation also shows an asymmetric characteristic.Chaotic vibrations are generated around the resonant frequency,irrespective of which linear oscillator is excited.The excitation threshold of these chaotic vibrations is dependent on the linear oscillator that is being excited.In addition,the difference between the energy transfer in the two opposite directions is used to further analyze the nonreciprocity in the system.The results show that the nonreciprocity significantly depends on the excitation frequency and the excitation amplitude.展开更多
Nonreciprocal devices are indispensable for building quantum networks and ubiquitous in modern communication technology.Here, we study perfect optical nonreciprocity in a three-mode optomechanical system with mechanic...Nonreciprocal devices are indispensable for building quantum networks and ubiquitous in modern communication technology.Here, we study perfect optical nonreciprocity in a three-mode optomechanical system with mechanical driving.The scheme relies on the interference between optomechanical interaction and mechanical driving.We find perfect optical nonreciprocity can be achieved even though nonreciprocal phase difference is zero if we drive the system by a mechanical driving with a nonzero phase.We obtain the essential conditions for perfect optical nonreciprocity and analyze properties of the optical nonreciprocal transmission.These results can be used to control optical transmission in quantum information processing.展开更多
Elastic diodes with nonreciprocity have the potential to enable unidirectional modulation of elastic waves.However,it is a challenge to achieve nonreciprocity at low frequencies(<100 Hz)using existing elastic diode...Elastic diodes with nonreciprocity have the potential to enable unidirectional modulation of elastic waves.However,it is a challenge to achieve nonreciprocity at low frequencies(<100 Hz)using existing elastic diodes.This paper proposes a quasizero-stiffness(QZS)elastic diode to resolve such a tough issue and fulfill high-quality low-frequency nonreciprocity.The proposed elastic diode is invented by combining a QZS locally resonant metamaterial with a linear one,where the beneficial nonlinearity of the QZS metamaterial facilitates opening an amplitude-dependent band gap at very low frequencies.Firstly,the dispersion relation of the QZS metamaterial is derived theoretically based on the harmonic balance method(HBM).Then,the transmissibility of the QZS elastic diode in both the forward and backward directions is calculated through theoretical analyses and numerical simulations.Additionally,the influences of system parameters on the low-frequency nonreciprocal effect are discussed.The results indicate that considerable nonreciprocity is observed at a quite low frequency(e.g.,9 Hz),which is achieved by amplitude-dependent local resonance combined with interface reflection.Finally,a machine learning-based design optimization is introduced to evaluate and enhance the nonreciprocal effect of the QZS elastic diode.With the aid of machine learning(ML),the computational cost of predicting nonreciprocal effects during design optimization can be significantly reduced.Through design optimization,the nonreciprocal frequency bandwidth can be broadened while maintaining considerable isolation quality at low frequencies.展开更多
The in-band full-duplex(IBFD)wireless system is a promising candidate for 6G and beyond,as it can double data throughput and enormously lower transmission latency by supporting simultaneous in-band transmission and re...The in-band full-duplex(IBFD)wireless system is a promising candidate for 6G and beyond,as it can double data throughput and enormously lower transmission latency by supporting simultaneous in-band transmission and reception of signals.Enabling IBFD systems requires a substantial mitigation of a transmitter(Tx)’s strong self-interference(SI)signal into the receiver(Rx)channel.However,current state-ofthe-art approaches to tackle this challenge are inefficient in terms of performance,cost,and complexity,hindering the commercialization of IBFD techniques.In this work,we devise and demonstrate an innovative approach to realize IBFD systems that exhibit superior performance with a low-cost and lesscomplex architecture in an all-passive module.Our scheme is based on meticulously combining polarization-division multiplexing(PDM)with ferromagnetic nonreciprocity to achieve ultra-high isolation between Tx and Rx channels.Such an unprecedented conception has become feasible thanks to a concurrent dual-mode circulator—a new component introduced for the first time—as a key feature of our module,and a dual-mode waveguide that transforms two orthogonally polarized waves into two orthogonal waveguide modes.In addition,we propose a unique passive tunable secondary SI cancellation(SIC)mechanism,which is embedded within the proposed module and boosts the isolation over a relatively broad bandwidth.We report,solely in the analog domain,experimental isolation levels of 50,70,and 80 dB over 340,101,and 33 MHz bandwidth at the center frequency of interest,respectively,with excellent tuning capability.Furthermore,the module is tested in two real IBFD scenarios to assess its performance in connection with Tx-to-Rx leakage and modulation error in the presence of a Tx’s strong interference signal.展开更多
We theoretically study the optical nonreciprocity in a piezo-optomechanical microdisk resonator,in which the cavity modes and the mechanical mode are optically pumped and piezoelectrically driven,respectively.For asym...We theoretically study the optical nonreciprocity in a piezo-optomechanical microdisk resonator,in which the cavity modes and the mechanical mode are optically pumped and piezoelectrically driven,respectively.For asymmetric optical pumping and different piezoelectrical drivings,our system shows some nonreciprocal optical responses.We find that our system can function as an optical isolator,a nonreciprocal amplifier,or a nonreciprocal phase shifter.展开更多
Sky radiative cooling has showcased great potential for passive refrigeration without extra energy consumption,while its cooling power and efficiency are confined by Kirchhoff’s law,that is,the emissivity is equal to...Sky radiative cooling has showcased great potential for passive refrigeration without extra energy consumption,while its cooling power and efficiency are confined by Kirchhoff’s law,that is,the emissivity is equal to the absorptivity.The recent development of thermal nonreciprocity that breaks the limitations of Kirchhoff’s law,especially in a broadband manner,makes nonreciprocal radiative cooling(NRC)possible.However,as there are few reports on NRC either theoretically or experimentally,it is necessary to evaluate the feasibility and worthiness of developing NRC.Here,we discussed the effects of NRC at around room temperature(298.15 K)from three perspectives:ideal selective radiators,non-selective radiators,and colored radiators,which are the current primary radiative coolers.Counterintuitively,we found that introducing thermal nonreciprocity barely improves sky radiative cooling,and only in the atmospheric window(8-13μm)even leads to a negative gain.The current findings break the intuition of NRC and offer a negative proof for the development of NRC devices.展开更多
Chiral and nonreciprocal quantum devices are crucial for signal routing and processing in a quantum network.In this work,we study the chirality and nonreciprocity of a giant atom coupled to a one-dimensional waveguide...Chiral and nonreciprocal quantum devices are crucial for signal routing and processing in a quantum network.In this work,we study the chirality and nonreciprocity of a giant atom coupled to a one-dimensional waveguide.We clarify that the chiral emission of the giant atom is not directly related to the time-reversal symmetry breaking but to the mirror-symmetry breaking.We propose a passive scheme,by extending the legs of the giant atom,to realize the chiral emission without breaking time-reversal symmetry.We prove that the time-reversal symmetry breaking alone via nonuniform coupling phases is not sufficient for the nonreciprocal single-photon scattering of the giant atom.The nonreciprocity needs both the time-reversal symmetry breaking and the finite external dissipation of the giant atom.Our work clarifies the roles of symmetries in the chirality and nonreciprocity of giant-atom systems and paves the way for the design of on-chip functional devices with superconducting giant atoms.展开更多
Radiative cooling has witnessed substantial progress while its performance is constrained by the thermal reciprocal Kirchhoff’s law.Violating Kirchhoff’s law to pursue nonreciprocal radiative cooling seems promising...Radiative cooling has witnessed substantial progress while its performance is constrained by the thermal reciprocal Kirchhoff’s law.Violating Kirchhoff’s law to pursue nonreciprocal radiative cooling seems promising;however,the energy conservation requirement and radiant flux integrated over the entire hemisphere make the nonreciprocal benefit insignificant.This commentary discusses the practical limits of nonreciprocal radiative cooling and points toward the future direction of directional radiative cooling.展开更多
Exceptional points(EPs)have been extensively explored in mechanical,acoustic,plasmonic,and photonic systems.However,little is known about the role of EPs in tailoring the dynamic tunability of optical devices.A specif...Exceptional points(EPs)have been extensively explored in mechanical,acoustic,plasmonic,and photonic systems.However,little is known about the role of EPs in tailoring the dynamic tunability of optical devices.A specific type of EPs known as chiral EPs has recently attracted much attention for controlling the flow of light and for building sensors with better responsivity.A recently demonstrated route to chiral EPs via lithographically defined symmetric Mie scatterers on the rim of resonators has not only provided the much-needed mechanical stability for studying chiral EPs,but also helped reduce losses originating from nanofabrication imperfections,facilitating the in-situ study of chiral EPs and their contribution to the dynamics and tunability of resonators.Here,we use asymmetric Mie scatterers to break the rotational symmetry of a microresonator,to demonstrate deterministic thermal tuning across a chiral EP,and to demonstrate EP-mediated chiral optical nonlinear response and efficient electro-optic tuning.Our results indicate asymmetric electro-optic modulation with up to 17 dB contrast at GHz and CMOS-compatible voltage levels.Such wafer-scale nano-manufacturing of chiral electro-optic modulators and the chiral EP-tailored tunning may facilitate new micro-resonator functionalities in quantum information processing,electromagnetic wave control,and optical interconnects.展开更多
Nonreciprocal devices are indispen.sablo for building quantuin networks and ubiquitous in modern communication technology.Here,we propose to take advantage of the interference between optome-chanical interaction and l...Nonreciprocal devices are indispen.sablo for building quantuin networks and ubiquitous in modern communication technology.Here,we propose to take advantage of the interference between optome-chanical interaction and lincarly-couplcd interaction to realize optical nonreciprocal transmission in a double-cavity optomechanical system.Particularly,we have derived essential conditions for perfect optical nonrcciprocity ancl analysed properties of the optical nonreciprocal transmission.These results can be used to control optical transmission in quantum information processing.展开更多
Synchronization is of importance in both fundamental and applied physics,but its demonstration at the micro/nanoscale is mainly limited to low-frequency oscillations such as mechanical resonators.We report the synchro...Synchronization is of importance in both fundamental and applied physics,but its demonstration at the micro/nanoscale is mainly limited to low-frequency oscillations such as mechanical resonators.We report the synchronization of two coupled optical microresonators,in which the high-frequency resonances in the optical domain are aligned with reduced noise.It is found that two types of synchronization regimes emerge with either the first-or second-order transition,both presenting a process of spontaneous symmetry breaking.In the second-order regime,the synchronization happens with an invariant topological character number and a larger detuning than that of the first-order case.Furthermore,an unconventional hysteresis behavior is revealed for a time-dependent coupling strength,breaking the static limitation and the temporal reciprocity.The synchronization of optical microresonators offers great potential in reconfigurable simulations of manybody physics and scalable photonic devices on a chip.展开更多
Optical nonreciprocity,which refers to the direction-dependent emission,scattering and absorption of photons,plays a very important role in quantum engineering and quantum information processing.Here,we propose an all...Optical nonreciprocity,which refers to the direction-dependent emission,scattering and absorption of photons,plays a very important role in quantum engineering and quantum information processing.Here,we propose an all-optical approach to achieve the optical dynamical switchable quantum nonreciprocity by an off-resonant chiral two-photon driving in a single microring cavity,which differs from the conventional nonreciprocal schemes.It is shown that the optical field with time-dependent statistical properties can be generated and the nonreciprocity flips periodically,with switchable photon blockade and photon-induced tunneling effects.We find that the dynamical system is robust and immune to the parameter variations,which loosens the parameter range of system.Meanwhile,the time window for one-way quantum information is sufficiently wide and tunable.Our work opens a new idea for the current quantum nonreciprocal research,which can facilitate a memory functionality and be used for future inmemory superconducting quantum compute.The other nonreciprocal quantum devices,i.e.,dynamical switchable nonreciprocal squeezing and entanglement,may be inspired by our method,which is expected to have important applications in future quantum technology.展开更多
We propose a scheme to achieve nonreciprocal single-photon transmission in a system consisting of a spinning whispering-gallery-mode resonator and a stationary resonator containing a scatterer,both coupled to a one-di...We propose a scheme to achieve nonreciprocal single-photon transmission in a system consisting of a spinning whispering-gallery-mode resonator and a stationary resonator containing a scatterer,both coupled to a one-dimensional waveguide.By tuning the Sagnac-Fizeau shift induced by the spinning resonator,high-contrast nonreciprocal transmission in both forward and backward directions can be realized.Furthermore,we investigate the influences of system parameters including waveguide-resonator coupling strength,inter-mode coupling strengths within two resonators,and inter-cavity coupling strength on nonreciprocal transmissions.The results indicate that the synergistic regulation of these parameters can adjust the position of the nonreciprocal transmission peak and achieve high-contrast nonreciprocal transmission.展开更多
Optical nonreciprocal transmission with unidirectional amplification in a gain-assisted cavity-QED system is investigated.The results demonstrate that unidirectional amplification of this system is induced by the phas...Optical nonreciprocal transmission with unidirectional amplification in a gain-assisted cavity-QED system is investigated.The results demonstrate that unidirectional amplification of this system is induced by the phase difference between the atom-cavity coupling strengths associated with the optical gain and a phase-controlled unidirectional amplifier can be achieved.The optimal parameter conditions for the observation of ideal unidirectional amplification are obtained analytically,and are shown to be dependent on phase,atom-cavity and cavity-cavity coupling strength,and atomic dissipation.In particular,it is found that atomic dissipation is another essential condition for the realization of nonreciprocal amplification other than breaking of the time-reversal symmetry,and our unidirectional amplifier is robust against atom-cavity coupling mismatch.Such unidirectional amplifiers are crucial nonreciprocal devices for controlling photon transmission and may have potential applications in quantum information processing.展开更多
Odd elasticity introduces active moduli to the antisymmetric components of the elastic tensor,which describe the asymmetric coupling between different deformation modes in a medium and quantify the work extracted duri...Odd elasticity introduces active moduli to the antisymmetric components of the elastic tensor,which describe the asymmetric coupling between different deformation modes in a medium and quantify the work extracted during quasi-static strain cycles.The introduction of active moduli renders the elastic tensor non-Hermitian,breaking the Maxwell-Betti reciprocity and enabling the observation of phenomena that cannot occur in traditional passive media.Here,we develop an analytical dynamic model for odd elastic circular plates to investigate the effects of odd elasticity on motion in rotationally symmetric geometries.We report a novel nonreciprocal rotating wave and explore the effects of different odd elastic moduli on chiral deformation.Nonreciprocal rotating waves represent a distinct dynamic mode,exhibiting unidirectional propagation with amplitude increasing or decreasing exclusively along a specific direction.The amplitude change during motion reveals the system’s non-conservation of energy.展开更多
We investigate nonreciprocal transmission in microcavity exciton polaritons and obtain analytical conditions for achieving unidirectional and circular transmission.The phase difference between two effective optomechan...We investigate nonreciprocal transmission in microcavity exciton polaritons and obtain analytical conditions for achieving unidirectional and circular transmission.The phase difference between two effective optomechanical couplings can regulate the interference of different channels between two photon modes,and control the direction of nonreciprocity,resulting in unidirectional forward and backward transmissions.Perfect nonreciprocal unidirectional transmission with zero losses is realized,which depends on exciton-photon-phonon couplings.Moreover,clockwise and counterclockwise circular transmissions are implemented by appropriately adjusting the phase of photon mode couplings.Our results open up exciting possibilities for implementing nonreciprocal photonic devices.展开更多
We present work on a cavity-driven QED system combining an asymmetrical Fabry–Perot cavity and N two-level atoms(TLAs)and show the convenience of simplifying from distinguishable atoms to undistinguishable bosons whe...We present work on a cavity-driven QED system combining an asymmetrical Fabry–Perot cavity and N two-level atoms(TLAs)and show the convenience of simplifying from distinguishable atoms to undistinguishable bosons when the atoms are prepared in the same initial state.Such simplification is valid even when the atoms are not prepared in the inphase condition,since any partial in-phase initial state will evolve into the ground state through a relaxation process.Thus,we get a reduced group of differential equations by introducing the Dicke states,and the under-zero Lyapunov exponents verify its stability.We also work out the collective unconventional photon blockade(UCPB)and get two kinds of giant nonreciprocal UCPBs(NUCPBs)in the weak-driving approximation.Results show that we can employ N noninteracting bosonic atoms to generate a collective UCPB instead of a monoatomic UCPB as the UCPB conditions do not vary with the number of atoms.Furthermore,the forward giant NUCPB only occurring for N larger than a certain number as well as the backward giant NUCPB are controllable by the cavity asymmetry and by the number of atoms.Our findings suggest a prospective approach to the generation of quantum nonreciprocity by N identical atoms.展开更多
With the urgently increasing demand for high-speed and large-capacity communication trans-mission,there remains a critical need for tunable terahertz(THz)devices with multi-channel in 5G/6G communication systems.A mag...With the urgently increasing demand for high-speed and large-capacity communication trans-mission,there remains a critical need for tunable terahertz(THz)devices with multi-channel in 5G/6G communication systems.A magnetic phase-coding meta-atom(MPM)is formed by the heterogeneous integration of La:YIG magneto-optical(MO)materials and Si microstructures.The MPM couples the magnetic induction phase of spin states with the propagation phase and can simultaneously satisfy the required output phase for dual frequencies under various external magnetic fields to realize the dynamic beam steering among multiple channels at 0.25 and 0.5 THz.The energy ratio of the target direction can reach 96.5%,and the nonreciprocal one-way transmission with a max isolation of 29.8 dB is realized due to the nonreciprocal phase shift of the MO layer.This nonreciprocal mechanism of magnetic induction reshaping of wavefront significantly holds promise for advancing integrated multi-functional THz devices with the characteristics of low-crosstalk,multi-channel,and multi-frequency,and has great potential to promote the development of THz large-capacity and high-speed communication.展开更多
We investigate the zeptosecond-timescale delayed ionization process induced by ultrafast laser propagation in different directions across the molecule.The experimental measurements by Grundmann et al.[Science 370339(2...We investigate the zeptosecond-timescale delayed ionization process induced by ultrafast laser propagation in different directions across the molecule.The experimental measurements by Grundmann et al.[Science 370339(2020)]serve as a basis for our study,where they extract the birth time delay of photoelectron emission from two nuclei,amounting to a few hundred zeptoseconds.By comparing and analyzing the results,we observe that asymmetric systems,such as the 2pσstate of HeH^(2+),exhibit nonequivalent responses to forward and backward laser propagation,resulting in an asymmetric dependence of the interference structure in the photoelectron momentum spectra.This process is considered as an ultrafast nonreciprocal phase shift with zeptosecond resolution.Through computational simulations,we explore the relationship between this kind of ultrafast nonreciprocity effect and molecular orbital symmetry.This study broadens our understanding of nonreciprocal physical mechanisms in the field of strong-field ultrafast dynamics,and provides a theoretical basis for the experimental investigation of the nonreciprocal phase shift within the zeptosecond timescale in the response processes of matter under ultrafast laser irradiation.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.12364008)the Ph.D.Research Startup Foundation of Yan’an University(Grant No.YDBK2019-54)the Yan’an High-level Talent Special Project(Grant No.2019263166)。
文摘Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectification performance.To address this issue,we developed a thermal rectification structure comprising a current-biased graphene-coated silicon carbide(SiC)substrate paired with another graphene-coated SiC substrate separated by a nanoscale vacuum gap.A current-biased graphene sheet generates nonreciprocal effect that actively modulates radiative energy transfer.Our theoretical framework demonstrates that the current-biased graphene achieves a high thermal diode efficiency even under a modest temperature difference.Remarkably,the thermal diode efficiency exceeds 0.8 at a temperature difference of just 100 K(between 300 K and 400 K).These findings highlight the synergistic enhancement from graphene coatings and current biasing,providing a viable strategy for nanoscale thermal management applications.
基金Project supported by the National Natural Science Foundation of China(Nos.12172246 and 11872274)the Natural Science Foundation of Tianjin of China(No.19JCZDJC32300)。
文摘The nonreciprocity of energy transfer is constructed in a nonlinear asymmetric oscillator system that comprises two nonlinear oscillators with different parameters placed between two identical linear oscillators.The slow-flow equation of the system is derived by the complexification-averaging method.The semi-analytical solutions to this equation are obtained by the least squares method,which are compared with the numerical solutions obtained by the Runge-Kutta method.The distribution of the average energy in the system is studied under periodic and chaotic vibration states,and the energy transfer along two opposite directions is compared.The effect of the excitation amplitude on the nonreciprocity of the system producing the periodic responses is analyzed,where a three-stage energy transfer phenomenon is observed.In the first stage,the energy transfer along the two opposite directions is approximately equal,whereas in the second stage,the asymmetric energy transfer is observed.The energy transfer is also asymmetric in the third stage,but the direction is reversed compared with the second stage.Moreover,the excitation amplitude for exciting the bifurcation also shows an asymmetric characteristic.Chaotic vibrations are generated around the resonant frequency,irrespective of which linear oscillator is excited.The excitation threshold of these chaotic vibrations is dependent on the linear oscillator that is being excited.In addition,the difference between the energy transfer in the two opposite directions is used to further analyze the nonreciprocity in the system.The results show that the nonreciprocity significantly depends on the excitation frequency and the excitation amplitude.
基金Supported by the National Natural Science Foundation of China under Grant Nos.41472126,11847018Natural Science Foundation of Guangxi Province under Grant No.2018GXNSFBA281003+1 种基金Starting Research Fund from the Guangxi Normal University(2017BQ022)Northeast Petroleum University Youth Foundation(NEPUQN2015–1–16)
文摘Nonreciprocal devices are indispensable for building quantum networks and ubiquitous in modern communication technology.Here, we study perfect optical nonreciprocity in a three-mode optomechanical system with mechanical driving.The scheme relies on the interference between optomechanical interaction and mechanical driving.We find perfect optical nonreciprocity can be achieved even though nonreciprocal phase difference is zero if we drive the system by a mechanical driving with a nonzero phase.We obtain the essential conditions for perfect optical nonreciprocity and analyze properties of the optical nonreciprocal transmission.These results can be used to control optical transmission in quantum information processing.
基金supported by the National Natural Science Foundation of China(Grant Nos.12122206,11972152,and 12272129)the Hong Kong Scholars Program(Grant No.XJ2022012).
文摘Elastic diodes with nonreciprocity have the potential to enable unidirectional modulation of elastic waves.However,it is a challenge to achieve nonreciprocity at low frequencies(<100 Hz)using existing elastic diodes.This paper proposes a quasizero-stiffness(QZS)elastic diode to resolve such a tough issue and fulfill high-quality low-frequency nonreciprocity.The proposed elastic diode is invented by combining a QZS locally resonant metamaterial with a linear one,where the beneficial nonlinearity of the QZS metamaterial facilitates opening an amplitude-dependent band gap at very low frequencies.Firstly,the dispersion relation of the QZS metamaterial is derived theoretically based on the harmonic balance method(HBM).Then,the transmissibility of the QZS elastic diode in both the forward and backward directions is calculated through theoretical analyses and numerical simulations.Additionally,the influences of system parameters on the low-frequency nonreciprocal effect are discussed.The results indicate that considerable nonreciprocity is observed at a quite low frequency(e.g.,9 Hz),which is achieved by amplitude-dependent local resonance combined with interface reflection.Finally,a machine learning-based design optimization is introduced to evaluate and enhance the nonreciprocal effect of the QZS elastic diode.With the aid of machine learning(ML),the computational cost of predicting nonreciprocal effects during design optimization can be significantly reduced.Through design optimization,the nonreciprocal frequency bandwidth can be broadened while maintaining considerable isolation quality at low frequencies.
基金supported by a Natural Sciences and Engineering Research Council(NSERC)-sponsored Industrial Research Chair program,an NSERC Discovery Grantin part by the Fonds de recherche du Québec Nature et technologies(FRQNT)Doctoral Fellowship of Amir Afshani funded by the Government of Québec Province.
文摘The in-band full-duplex(IBFD)wireless system is a promising candidate for 6G and beyond,as it can double data throughput and enormously lower transmission latency by supporting simultaneous in-band transmission and reception of signals.Enabling IBFD systems requires a substantial mitigation of a transmitter(Tx)’s strong self-interference(SI)signal into the receiver(Rx)channel.However,current state-ofthe-art approaches to tackle this challenge are inefficient in terms of performance,cost,and complexity,hindering the commercialization of IBFD techniques.In this work,we devise and demonstrate an innovative approach to realize IBFD systems that exhibit superior performance with a low-cost and lesscomplex architecture in an all-passive module.Our scheme is based on meticulously combining polarization-division multiplexing(PDM)with ferromagnetic nonreciprocity to achieve ultra-high isolation between Tx and Rx channels.Such an unprecedented conception has become feasible thanks to a concurrent dual-mode circulator—a new component introduced for the first time—as a key feature of our module,and a dual-mode waveguide that transforms two orthogonally polarized waves into two orthogonal waveguide modes.In addition,we propose a unique passive tunable secondary SI cancellation(SIC)mechanism,which is embedded within the proposed module and boosts the isolation over a relatively broad bandwidth.We report,solely in the analog domain,experimental isolation levels of 50,70,and 80 dB over 340,101,and 33 MHz bandwidth at the center frequency of interest,respectively,with excellent tuning capability.Furthermore,the module is tested in two real IBFD scenarios to assess its performance in connection with Tx-to-Rx leakage and modulation error in the presence of a Tx’s strong interference signal.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61941501,61775062,11574092,61378012,and 91121023)the Doctoral Program of Guangdong Natural Science Foundation,China(Grant No.2018A030310109)+1 种基金the Doctoral Project of Guangdong Medical University,China(Grant No.B2017019)the Open Project of the Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of the Ministry of Education,Hunan Normal University,China(Grant No.QSQC1808).
文摘We theoretically study the optical nonreciprocity in a piezo-optomechanical microdisk resonator,in which the cavity modes and the mechanical mode are optically pumped and piezoelectrically driven,respectively.For asymmetric optical pumping and different piezoelectrical drivings,our system shows some nonreciprocal optical responses.We find that our system can function as an optical isolator,a nonreciprocal amplifier,or a nonreciprocal phase shifter.
基金the financial support by National Natural Science Foundation of China(52422603,92463311,52211540005)the Open Project Program of Wuhan National Laboratory for Optoelectronics(2021WNLOKF004)+2 种基金Interdisciplinary Research Program of HUST(5003120094)Natural Science Foundation of Hubei Province(2023AFA072)the Fundamental Research Funds for the Central Universities(YCJJ20242102).
文摘Sky radiative cooling has showcased great potential for passive refrigeration without extra energy consumption,while its cooling power and efficiency are confined by Kirchhoff’s law,that is,the emissivity is equal to the absorptivity.The recent development of thermal nonreciprocity that breaks the limitations of Kirchhoff’s law,especially in a broadband manner,makes nonreciprocal radiative cooling(NRC)possible.However,as there are few reports on NRC either theoretically or experimentally,it is necessary to evaluate the feasibility and worthiness of developing NRC.Here,we discussed the effects of NRC at around room temperature(298.15 K)from three perspectives:ideal selective radiators,non-selective radiators,and colored radiators,which are the current primary radiative coolers.Counterintuitively,we found that introducing thermal nonreciprocity barely improves sky radiative cooling,and only in the atmospheric window(8-13μm)even leads to a negative gain.The current findings break the intuition of NRC and offer a negative proof for the development of NRC devices.
基金supported by the National Natural Science Foundation of China (Grant No.12475025)。
文摘Chiral and nonreciprocal quantum devices are crucial for signal routing and processing in a quantum network.In this work,we study the chirality and nonreciprocity of a giant atom coupled to a one-dimensional waveguide.We clarify that the chiral emission of the giant atom is not directly related to the time-reversal symmetry breaking but to the mirror-symmetry breaking.We propose a passive scheme,by extending the legs of the giant atom,to realize the chiral emission without breaking time-reversal symmetry.We prove that the time-reversal symmetry breaking alone via nonuniform coupling phases is not sufficient for the nonreciprocal single-photon scattering of the giant atom.The nonreciprocity needs both the time-reversal symmetry breaking and the finite external dissipation of the giant atom.Our work clarifies the roles of symmetries in the chirality and nonreciprocity of giant-atom systems and paves the way for the design of on-chip functional devices with superconducting giant atoms.
基金funding from the National Natural Science Foundation of China(52422603,52076087,and 52211540005)the Interdisciplinary Research Program of HUST(5003120094)the Natural Science Foundation of Hubei Province(2023AFA072).
文摘Radiative cooling has witnessed substantial progress while its performance is constrained by the thermal reciprocal Kirchhoff’s law.Violating Kirchhoff’s law to pursue nonreciprocal radiative cooling seems promising;however,the energy conservation requirement and radiant flux integrated over the entire hemisphere make the nonreciprocal benefit insignificant.This commentary discusses the practical limits of nonreciprocal radiative cooling and points toward the future direction of directional radiative cooling.
基金supported by the Defense Advanced Research Projects Agency(N660012114034)H.L.acknowledges the scholarship provided by the Republic of Korea Navy(ROK Nawy)+1 种基金The design and fabrication of the micro-heater and chiral MRR are supported by AFOSR(FA9550-18-1-0300)S.K.O.acknowledges the Air Force Offce of Scientific Research(AFOSR)Multi-University Research Initiative(FA9550-21-1-0202)and AFOSR(FA9550-18-1-0235)。
文摘Exceptional points(EPs)have been extensively explored in mechanical,acoustic,plasmonic,and photonic systems.However,little is known about the role of EPs in tailoring the dynamic tunability of optical devices.A specific type of EPs known as chiral EPs has recently attracted much attention for controlling the flow of light and for building sensors with better responsivity.A recently demonstrated route to chiral EPs via lithographically defined symmetric Mie scatterers on the rim of resonators has not only provided the much-needed mechanical stability for studying chiral EPs,but also helped reduce losses originating from nanofabrication imperfections,facilitating the in-situ study of chiral EPs and their contribution to the dynamics and tunability of resonators.Here,we use asymmetric Mie scatterers to break the rotational symmetry of a microresonator,to demonstrate deterministic thermal tuning across a chiral EP,and to demonstrate EP-mediated chiral optical nonlinear response and efficient electro-optic tuning.Our results indicate asymmetric electro-optic modulation with up to 17 dB contrast at GHz and CMOS-compatible voltage levels.Such wafer-scale nano-manufacturing of chiral electro-optic modulators and the chiral EP-tailored tunning may facilitate new micro-resonator functionalities in quantum information processing,electromagnetic wave control,and optical interconnects.
基金L. Yang was supported by the National Natural Science Foundation of China (Grant No. 11804066)the China Postdoctoral Science Foundation (Grant No. 2018M630337)Fundamental Research Funds for the Central Universities (Grant No. 3072019CFM0405).
文摘Nonreciprocal devices are indispen.sablo for building quantuin networks and ubiquitous in modern communication technology.Here,we propose to take advantage of the interference between optome-chanical interaction and lincarly-couplcd interaction to realize optical nonreciprocal transmission in a double-cavity optomechanical system.Particularly,we have derived essential conditions for perfect optical nonrcciprocity ancl analysed properties of the optical nonreciprocal transmission.These results can be used to control optical transmission in quantum information processing.
基金We thank Linran Fan,Qi-Tao Cao,and Mian Zhang for fruitful discussions.This work was supported by the National Key R&D Program of China(Grant Nos.2016YFA0301302 and 2018YFB2200401)NSFC(Grant Nos.11825402,61435001,11654003,and 11674200),and High-Performance Computing Platform of Peking University.The authors declare that they have no competing financial interests.
文摘Synchronization is of importance in both fundamental and applied physics,but its demonstration at the micro/nanoscale is mainly limited to low-frequency oscillations such as mechanical resonators.We report the synchronization of two coupled optical microresonators,in which the high-frequency resonances in the optical domain are aligned with reduced noise.It is found that two types of synchronization regimes emerge with either the first-or second-order transition,both presenting a process of spontaneous symmetry breaking.In the second-order regime,the synchronization happens with an invariant topological character number and a larger detuning than that of the first-order case.Furthermore,an unconventional hysteresis behavior is revealed for a time-dependent coupling strength,breaking the static limitation and the temporal reciprocity.The synchronization of optical microresonators offers great potential in reconfigurable simulations of manybody physics and scalable photonic devices on a chip.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFA1400702)National Natural Science Foundation of China(Grant No.11975103)。
文摘Optical nonreciprocity,which refers to the direction-dependent emission,scattering and absorption of photons,plays a very important role in quantum engineering and quantum information processing.Here,we propose an all-optical approach to achieve the optical dynamical switchable quantum nonreciprocity by an off-resonant chiral two-photon driving in a single microring cavity,which differs from the conventional nonreciprocal schemes.It is shown that the optical field with time-dependent statistical properties can be generated and the nonreciprocity flips periodically,with switchable photon blockade and photon-induced tunneling effects.We find that the dynamical system is robust and immune to the parameter variations,which loosens the parameter range of system.Meanwhile,the time window for one-way quantum information is sufficiently wide and tunable.Our work opens a new idea for the current quantum nonreciprocal research,which can facilitate a memory functionality and be used for future inmemory superconducting quantum compute.The other nonreciprocal quantum devices,i.e.,dynamical switchable nonreciprocal squeezing and entanglement,may be inspired by our method,which is expected to have important applications in future quantum technology.
基金financially supported by the National Natural Science Foundation of China(12064045)。
文摘We propose a scheme to achieve nonreciprocal single-photon transmission in a system consisting of a spinning whispering-gallery-mode resonator and a stationary resonator containing a scatterer,both coupled to a one-dimensional waveguide.By tuning the Sagnac-Fizeau shift induced by the spinning resonator,high-contrast nonreciprocal transmission in both forward and backward directions can be realized.Furthermore,we investigate the influences of system parameters including waveguide-resonator coupling strength,inter-mode coupling strengths within two resonators,and inter-cavity coupling strength on nonreciprocal transmissions.The results indicate that the synergistic regulation of these parameters can adjust the position of the nonreciprocal transmission peak and achieve high-contrast nonreciprocal transmission.
基金supported by China Postdoctoral Science Foundation(2023M732028)Zhejiang Province Key Laboratory of Quantum Technology and Device(20230201)+1 种基金National Key Research and Development Program of China(2021YFA1400602)National Natural Science Foundation of China(11864018,12164022,12174288,12274326)。
文摘Optical nonreciprocal transmission with unidirectional amplification in a gain-assisted cavity-QED system is investigated.The results demonstrate that unidirectional amplification of this system is induced by the phase difference between the atom-cavity coupling strengths associated with the optical gain and a phase-controlled unidirectional amplifier can be achieved.The optimal parameter conditions for the observation of ideal unidirectional amplification are obtained analytically,and are shown to be dependent on phase,atom-cavity and cavity-cavity coupling strength,and atomic dissipation.In particular,it is found that atomic dissipation is another essential condition for the realization of nonreciprocal amplification other than breaking of the time-reversal symmetry,and our unidirectional amplifier is robust against atom-cavity coupling mismatch.Such unidirectional amplifiers are crucial nonreciprocal devices for controlling photon transmission and may have potential applications in quantum information processing.
基金The Innovative Projects of Key Disciplines of Civil Engineering of Changsha University of Science and Technology,24ZDXK07,Andi Lai。
文摘Odd elasticity introduces active moduli to the antisymmetric components of the elastic tensor,which describe the asymmetric coupling between different deformation modes in a medium and quantify the work extracted during quasi-static strain cycles.The introduction of active moduli renders the elastic tensor non-Hermitian,breaking the Maxwell-Betti reciprocity and enabling the observation of phenomena that cannot occur in traditional passive media.Here,we develop an analytical dynamic model for odd elastic circular plates to investigate the effects of odd elasticity on motion in rotationally symmetric geometries.We report a novel nonreciprocal rotating wave and explore the effects of different odd elastic moduli on chiral deformation.Nonreciprocal rotating waves represent a distinct dynamic mode,exhibiting unidirectional propagation with amplitude increasing or decreasing exclusively along a specific direction.The amplitude change during motion reveals the system’s non-conservation of energy.
基金supported by the National Natural Science Foundation of China(Grant Nos.12104374,12164042,and 12264045)the Natural Science Foundation of Gansu Province,China(Grant No.20JR5RA526).
文摘We investigate nonreciprocal transmission in microcavity exciton polaritons and obtain analytical conditions for achieving unidirectional and circular transmission.The phase difference between two effective optomechanical couplings can regulate the interference of different channels between two photon modes,and control the direction of nonreciprocity,resulting in unidirectional forward and backward transmissions.Perfect nonreciprocal unidirectional transmission with zero losses is realized,which depends on exciton-photon-phonon couplings.Moreover,clockwise and counterclockwise circular transmissions are implemented by appropriately adjusting the phase of photon mode couplings.Our results open up exciting possibilities for implementing nonreciprocal photonic devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12164022 and 12174288)Natural Science Foundation of Jiangxi Province of China(Grant No.20232BAB201044)+1 种基金Scientific Research Foundation of the Education Department of Jiangxi Province of China(Grant No.GJJ211039)China Postdoctoral Science Foundation(Grant No.2023M732028)。
文摘We present work on a cavity-driven QED system combining an asymmetrical Fabry–Perot cavity and N two-level atoms(TLAs)and show the convenience of simplifying from distinguishable atoms to undistinguishable bosons when the atoms are prepared in the same initial state.Such simplification is valid even when the atoms are not prepared in the inphase condition,since any partial in-phase initial state will evolve into the ground state through a relaxation process.Thus,we get a reduced group of differential equations by introducing the Dicke states,and the under-zero Lyapunov exponents verify its stability.We also work out the collective unconventional photon blockade(UCPB)and get two kinds of giant nonreciprocal UCPBs(NUCPBs)in the weak-driving approximation.Results show that we can employ N noninteracting bosonic atoms to generate a collective UCPB instead of a monoatomic UCPB as the UCPB conditions do not vary with the number of atoms.Furthermore,the forward giant NUCPB only occurring for N larger than a certain number as well as the backward giant NUCPB are controllable by the cavity asymmetry and by the number of atoms.Our findings suggest a prospective approach to the generation of quantum nonreciprocity by N identical atoms.
基金supported by the National Natural Science Foun-dation of China(Grant Nos.62371258,62335012,62205160,and 62435010)the Tianjin Youth Science and Technology Talent Project(Grant No.QN20230227)+1 种基金the Natural Science Foundation of Tianjin(Grant No.24JCYBJC01860)the Fundamental Research Funds for the Central Universities,Nan-kai University(Grant No.075-63253215).
文摘With the urgently increasing demand for high-speed and large-capacity communication trans-mission,there remains a critical need for tunable terahertz(THz)devices with multi-channel in 5G/6G communication systems.A magnetic phase-coding meta-atom(MPM)is formed by the heterogeneous integration of La:YIG magneto-optical(MO)materials and Si microstructures.The MPM couples the magnetic induction phase of spin states with the propagation phase and can simultaneously satisfy the required output phase for dual frequencies under various external magnetic fields to realize the dynamic beam steering among multiple channels at 0.25 and 0.5 THz.The energy ratio of the target direction can reach 96.5%,and the nonreciprocal one-way transmission with a max isolation of 29.8 dB is realized due to the nonreciprocal phase shift of the MO layer.This nonreciprocal mechanism of magnetic induction reshaping of wavefront significantly holds promise for advancing integrated multi-functional THz devices with the characteristics of low-crosstalk,multi-channel,and multi-frequency,and has great potential to promote the development of THz large-capacity and high-speed communication.
基金supported by the National Natural Science Foundation of China(Grant No.12204136)the Hainan Provincial Natural Science Foundation of China(Grant No.122QN217)。
文摘We investigate the zeptosecond-timescale delayed ionization process induced by ultrafast laser propagation in different directions across the molecule.The experimental measurements by Grundmann et al.[Science 370339(2020)]serve as a basis for our study,where they extract the birth time delay of photoelectron emission from two nuclei,amounting to a few hundred zeptoseconds.By comparing and analyzing the results,we observe that asymmetric systems,such as the 2pσstate of HeH^(2+),exhibit nonequivalent responses to forward and backward laser propagation,resulting in an asymmetric dependence of the interference structure in the photoelectron momentum spectra.This process is considered as an ultrafast nonreciprocal phase shift with zeptosecond resolution.Through computational simulations,we explore the relationship between this kind of ultrafast nonreciprocity effect and molecular orbital symmetry.This study broadens our understanding of nonreciprocal physical mechanisms in the field of strong-field ultrafast dynamics,and provides a theoretical basis for the experimental investigation of the nonreciprocal phase shift within the zeptosecond timescale in the response processes of matter under ultrafast laser irradiation.
