For the quantum error correction and noisy intermediate-scale quantum algorithms to function with high efficiency,the raw fidelity of quantum logic gates on physical qubits needs to satisfy strict requirements.The neu...For the quantum error correction and noisy intermediate-scale quantum algorithms to function with high efficiency,the raw fidelity of quantum logic gates on physical qubits needs to satisfy strict requirements.The neutral atom quantum computing equipped with Rydberg blockade gates has made impressive progress recently,which makes it worthwhile to explore its potential in the two-qubit entangling gates,including the controlledphase gate,and in particular,the CZ gate.Provided the quantum coherence is well preserved,improving the fidelity of Rydberg blockade gates calls for special mechanisms to deal with adverse effects caused by realistic experimental conditions.Here,the heralded very-high-fidelity Rydberg blockade controlled-phase gate is designed to address these issues,which contains self-correction and projection as the key steps.This trailblazing method builds upon the previously established buffer-atom-mediated gate framework,with a special form of symmetry under parity–time transformation playing a crucial role in the process.We further analyze the performance with respect to a few typical sources of imperfections.This procedure can also be regarded as quantum hardware error correction or mitigation.While this paper by itself does not cover every single subtle issue and still contains many oversimplifications,we find it reasonable to anticipate a very-high-fidelity two-qubit quantum logic gate operated in the sense of heralded but probabilistic,whose gate error can be reduced to the level of 10^(-4)–10^(-6)or even lower with reasonably high possibilities.展开更多
Solid-state rare-earth ions are promising candidates for implementing repeater nodes for quantum networks.However,the state-of-the-art quantum nodes use only a single qubit per node,which greatly limits the functional...Solid-state rare-earth ions are promising candidates for implementing repeater nodes for quantum networks.However,the state-of-the-art quantum nodes use only a single qubit per node,which greatly limits the functionality of the node and the scalability of the network.Here,we propose a scheme that utilizes a hybrid system of two ion qubits coupled to a nanophotonic cavity as a quantum node.Simultaneously applying a fast adiabatic pulse to the two ions can lead to an effective interaction between the two ion spin qubits by exchanging virtual photons in the cavity.Using this interaction,a controlled phase gate between the two ion qubits can be realized with a fidelity of 99.6%.Further utilizing this interaction,entangled states within the node can be generated deterministically with high fidelity,and are robust to a variety of noises and fluctuations.These results pave a way for fully functional quantum repeater nodes based on solid-state rare-earth ions.展开更多
In this work, we propose a high-fidelity phonon-mediated entangling gate in a hybrid mechanical system based on two silicon-vacancy color centers in diamond. In order to suppress the influence of the spin decoherence ...In this work, we propose a high-fidelity phonon-mediated entangling gate in a hybrid mechanical system based on two silicon-vacancy color centers in diamond. In order to suppress the influence of the spin decoherence on the entangling gate, we use a continuous dynamical decoupling approach to create new dressed spin states, which are less sensitive to environmental fluctuations and exhibit an extended T_(2)^(*) spin dephasing time. The effective spin-spin Hamiltonian modified by the mechanical driving field and the corresponding master equation are derived in the dispersive regime. We show that in the presence of the mechanical driving field, the effective spin-spin coupling can be highly controlled. By calculating the entangling gate fidelity in the dressed basis, we find that once the mechanical field is turned on, the gate fidelity can be significantly improved. In particular, under an optimized spin-phonon detuning and a stronger Rabi frequency of the mechanical driving field, the two-qubit gate is capable of reaching fidelity exceeding 0.99. Moreover, by employing appropriate driving modulation, we show that a highfidelity full quantum gate can be also realized, in which the initial and final spin states are on a bare basis. Our work provides a promising scheme for realizing high-fidelity quantum information processing.展开更多
Spin qubits and superconducting qubits are promising candidates for realizing solid-state quantum information processors.Designing a hybrid architecture that combines the advantages of different qubits on the same chi...Spin qubits and superconducting qubits are promising candidates for realizing solid-state quantum information processors.Designing a hybrid architecture that combines the advantages of different qubits on the same chip is a highly desirable but challenging goal.Here we propose a hybrid architecture that utilizes a high-impedance SQUID array resonator as a quantum bus,thereby coherently coupling different solid-state qubits.We employ a resonant exchange spin qubit hosted in a triple quantum dot and a superconducting transmon qubit.Since this hybrid system is highly tunable,it can operate in a dispersive regime,where the interaction between the different qubits is mediated by virtual photons.By utilizing such interactions,entangling gate operations between different qubits can be realized in a short time of 30 ns with a fidelity of up to 96.5%under realistic parameter conditions.Further utilizing this interaction,remote entangled state between different qubits can be prepared and is robust to perturbations of various parameters.These results pave the way for exploring efficient fault-tolerant quantum computation on hybrid quantum architecture platforms.展开更多
We propose a novel scheme for generating the entanglement of two oscillating mirrors in an optomechanical system via a flying atom. In this scheme, a two-level atom, in an arbitrary superposition state, passes through...We propose a novel scheme for generating the entanglement of two oscillating mirrors in an optomechanical system via a flying atom. In this scheme, a two-level atom, in an arbitrary superposition state, passes through an optomechanical system with two oscillating cavity-mirrors, and then its states are detected. In this way, we can generate the entangled states of the two oscillating mirrors. We derive the analytical expressions of the entangled states and make numerical calculations. We find that the entanglement of the two oscillating mirrors can be controlled by the initial state of the atom, the optomechanical coupling strength, and the coupling strength between the atom and the cavity field. We investigate the dynamics of the system with dissipations and discuss the experimental feasibility.展开更多
A scheme is presented for the generation of entangled states for two cavity mirrors. In the scheme each mirror initially in a vacuum state interacts with a weak coherent field, resulting in a photon-number dependent k...A scheme is presented for the generation of entangled states for two cavity mirrors. In the scheme each mirror initially in a vacuum state interacts with a weak coherent field, resulting in a photon-number dependent kick. The detection of a photon leaking from the cavities collapses the two mirrors to an entangled state.展开更多
Considering two light beams which are in general single-mode Gaussian states and incident on input ports of an ideal beam splitter, respectively, this paper investigates how separability and entanglement of the output...Considering two light beams which are in general single-mode Gaussian states and incident on input ports of an ideal beam splitter, respectively, this paper investigates how separability and entanglement of the output lights depend on degrees of nonclassicality and purities of the input states. The minimum and maximum amounts of attainable entanglement in the output state are found展开更多
A new scheme for quantum teleportation of single quantum bit state with using continuous variables entangling channel is presented. In our scheme two entangled light fields are employed. An outstanding characteristic ...A new scheme for quantum teleportation of single quantum bit state with using continuous variables entangling channel is presented. In our scheme two entangled light fields are employed. An outstanding characteristic of this scheme is that one atomic state is transmitted directly to another atom without using the third atom as the mediate.展开更多
A scheme is presented for the generation of entangled states for two atoms trapped in two distant cavities. In the scheme each atom is resonantly coupled with the respective cavity mode and driven by a strong classica...A scheme is presented for the generation of entangled states for two atoms trapped in two distant cavities. In the scheme each atom is resonantly coupled with the respective cavity mode and driven by a strong classical field. The detection of a photon decaying from the cavities and passing through a beam-splitter collapses the atoms to an entangled state. The required atom-field interaction time is very short and thus the decoherence effect is suppressed. Our scheme is within the reach of presently available cavity QED techniques.展开更多
We propose a scheme for the generation of two collections of atoms trapped in distant cavities connected by an optical fiber.The virtual photon exchange leads to the entanglement between these two atomic ensembles.Dur...We propose a scheme for the generation of two collections of atoms trapped in distant cavities connected by an optical fiber.The virtual photon exchange leads to the entanglement between these two atomic ensembles.During the operation the atomic system,cavity modes,and fiber are not excited,which is important in view of decoherence.展开更多
A scheme has been proposed for generating the macroscopic entanglement between the mesoscopic squeezed vacuum states and mesoscopic coherent states by considering both the two-photon interaction and the single photon ...A scheme has been proposed for generating the macroscopic entanglement between the mesoscopic squeezed vacuum states and mesoscopic coherent states by considering both the two-photon interaction and the single photon interaction of N two-level atoms in cavities with high quality factor assisted by a strong driving field. Moreover, we derive the dissipative interaction models for single photon interaction and two-photon interaction, respectively. The corresponding analytical expressions of the fidelities can be given. Our scheme can be realized in the current techniques on the cavity QED.展开更多
Limited by the thermal environment, the entanglement of a massive object is extremely difficult to generate. Based on a coherent scattering mechanism, we propose a scheme to generate the entanglement of two optically ...Limited by the thermal environment, the entanglement of a massive object is extremely difficult to generate. Based on a coherent scattering mechanism, we propose a scheme to generate the entanglement of two optically levitated nanospheres through the Coulomb interaction. Two nanospheres are charged and coupled to each other through the Coulomb interaction.In this manner, the entanglement of two nanospheres is induced either under a weak/strong optomechanical coupling regime or under an ultra-strong optomechanical coupling regime. The charges, radius and distance of the two nanospheres are taken into consideration to enhance the Coulomb interaction, thereby achieving a higher degree of entanglement in the absence of ground-state cooling. The corresponding maximum entanglement can be attained as the dynamics of the system approaches the boundary between the steady and the unsteady regimes. This provides a useful resource for both quantum-enhanced sensing and quantum information processing, as well as a new platform for studying many-body physics.展开更多
The dynamic generation of spin entanglement between two distant sites in a XY model with 1/r 2 decay long-range couplings was studied.Due to the linear dispersion relationε(k)~|k|of magnons in such a model,a well-loc...The dynamic generation of spin entanglement between two distant sites in a XY model with 1/r 2 decay long-range couplings was studied.Due to the linear dispersion relationε(k)~|k|of magnons in such a model,a well-located spin state can be dynamically split into two moving entangled local wave packets without changing their shapes.Interestingly,when such two wave packets meet at the diametrically opposite site after the fast periodτ=Nπ/J,the initial well-located state is completely recurrent.Numerical calculation was performed to confirm the analytical result even if the ring system of sizes N up to several thousands is considered.The truncation approximation for the coupling strengths was also studied.Numerical simulation shows that the above conclusions still hold even if the range of the coupling strength is truncated to a relatively short scale compared with the size of the spin system.展开更多
We present a robust quantum optimal control framework for implementing fast entangling gates on ion-trap quantum processors.The framework leverages tailored laser pulses to drive the multiple vibrational sidebands of ...We present a robust quantum optimal control framework for implementing fast entangling gates on ion-trap quantum processors.The framework leverages tailored laser pulses to drive the multiple vibrational sidebands of the ions to create phonon-mediated entangling gates and,unlike the state of the art,requires neither weakcoupling Lamb-Dicke approximation nor perturbation treatment.With the application of gradient-based optimal control,it enables finding amplitude-and phase-modulated laser control protocols that work without the Lamb-Dicke approximation,promising gate speeds on the order of microseconds comparable to the characteristic trap frequencies.Also,robustness requirements on the temperature of the ions and initial optical phase can be conveniently included to pursue high-quality fast gates against experimental imperfections.Our approach represents a step in speeding up quantum gates to achieve larger quantum circuits for quantum computation and simulation,and thus can find applications in near-future experiments.展开更多
Due to their high mechanical compliance and excellent biocompatibility,conductive hydrogels exhibit significant potential for applications in flexible electronics.However,as the demand for high sensitivity,superior me...Due to their high mechanical compliance and excellent biocompatibility,conductive hydrogels exhibit significant potential for applications in flexible electronics.However,as the demand for high sensitivity,superior mechanical properties,and strong adhesion performance continues to grow,many conventional fabrication methods remain complex and costly.Herein,we propose a simple and efficient strategy to construct an entangled network hydrogel through a liquid-metal-induced cross-linking reaction,hydrogel demonstrates outstanding properties,including exceptional stretchability(1643%),high tensile strength(366.54 kPa),toughness(350.2 kJ m^(−3)),and relatively low mechanical hysteresis.The hydrogel exhibits long-term stable reusable adhesion(104 kPa),enabling conformal and stable adhesion to human skin.This capability allows it to effectively capture high-quality epidermal electrophysiological signals with high signal-to-noise ratio(25.2 dB)and low impedance(310 ohms).Furthermore,by integrating advanced machine learning algorithms,achieving an attention classification accuracy of 91.38%,which will significantly impact fields like education,healthcare,and artificial intelligence.展开更多
Implementing quantum wireless multi-hop network communication is essential to improve the global quantum network system. In this paper, we employ eight-level GHZ states as quantum channels to realize multi-hop quantum...Implementing quantum wireless multi-hop network communication is essential to improve the global quantum network system. In this paper, we employ eight-level GHZ states as quantum channels to realize multi-hop quantum communication, and utilize the logical relationship between the measurements of each node to derive the unitary operation performed by the end node. The hierarchical simultaneous entanglement switching(HSES) method is adopted, resulting in a significant reduction in the consumption of classical information compared to multi-hop quantum teleportation(QT)based on general simultaneous entanglement switching(SES). In addition, the proposed protocol is simulated on the IBM Quantum Experiment platform(IBM QE). Then, the data obtained from the experiment are analyzed using quantum state tomography, which verifies the protocol's good fidelity and accuracy. Finally, by calculating fidelity, we analyze the impact of four different types of noise(phase-damping, amplitude-damping, phase-flip and bit-flip) in this protocol.展开更多
The no-cloning theorem has sparked considerable interest in achieving high-fidelity approximate quantum cloning.Most of the previous studies mainly focused on the cloning of single particle states,and cloning schemes ...The no-cloning theorem has sparked considerable interest in achieving high-fidelity approximate quantum cloning.Most of the previous studies mainly focused on the cloning of single particle states,and cloning schemes used there are incapable of cloning quantum entangled states in multipartite systems.Few schemes were proposed for cloning multiparticle states,which consume more entanglement resources with loss of qubits,and the fidelity of the cloned state is relatively low.In this paper,cloning schemes for bipartite and tripartite entangled states based on photonic quantum walk and entanglement swapping are proposed.The results show that according to the proposed schemes,two high-fidelity(up to 0.75)cloned states can be obtained with less quantum resource consumption.Because of the simple cloning steps,few quantum resources and high fidelity,these schemes are both efficient and feasible.Moreover,this cloning machine eliminates the need for tracing out cloning machine,thereby minimizing resource waste.展开更多
Entanglement plays a key role in quantum physics, but how much information it can extract from many-body systems is still an open question, particularly regarding quantum criticalities and emergent symmetries. In this...Entanglement plays a key role in quantum physics, but how much information it can extract from many-body systems is still an open question, particularly regarding quantum criticalities and emergent symmetries. In this work, we systematically study the entanglement entropy(EE) and derivative entanglement entropy(DEE) near quantum phase transitions in various quantum many-body systems. A one-parameter scaling relation between the DEE and system size at the critical point has been derived for the first time, which successfully obtains the critical exponent via data collapse. Furthermore, we find that the EE peaks at the(emergent) symmetryenhanced first-order transition, reflecting higher symmetry breaking. This work provides a new paradigm for quantum many-body research from the perspective of EE and DEE.展开更多
The rapid advancements of ultrafast intense laser technology have opened new avenues for investigating entanglement in laser-induced systems. However, the application of these advances in quantum technology requires a...The rapid advancements of ultrafast intense laser technology have opened new avenues for investigating entanglement in laser-induced systems. However, the application of these advances in quantum technology requires a reliable and universally applicable method for enhancing and regulating entanglement. Here we demonstrate how a few-cycle intense laser field can significantly enhance the degree of entanglement compared to its multi-cycle counterpart, using the example of electron–electron entanglement of orbital angular momentum(OAM) states in recollision-excitation non-sequential double ionization of Ar atoms. By confining the ionization dynamics to a specific narrow time window, the few-cycle pulse purifies the electron trajectories, thereby ensuring high coherence between entangled OAM channels and enhancing entanglement. Furthermore, the degree of entanglement can be efficiently modulated by varying the carrier envelope phase of the few-cycle laser pulse, which is achieved by altering the population across OAM channels. Optimizing coherence through electron trajectory purification with a designed specific temporal waveform of laser field provides a general pathway for enhancing entanglement in laser-induced systems.展开更多
Pairs of entangled vortex photons can promise new prospects of application in quantum computing and cryptography.We investigate the possibility of generating such states via two-level atom emission induced by a single...Pairs of entangled vortex photons can promise new prospects of application in quantum computing and cryptography.We investigate the possibility of generating such states via two-level atom emission induced by a single photon wave packet with a definite total angular momentum(TAM).The entangled pair produced in this process possesses well-defined mean TAM with the TAM variation being much smaller than h.On top of that,the variation exponentially decreases with the increase in TAM of the incident photon.Our model allows one to track the time evolution of the state of the entangled pair.An experimentally feasible scenario is assumed,in which the incident photon interacts with a spatially confined atomic target.We conclude that induced emission can be used as a source of entangled vortex photons with applications in atomic physics experiments,quantum optics,and quantum information sciences.展开更多
基金supported by the Science and Technology Commission of Shanghai Municipality(Grant No.24DP2600202)the National Key R&D Program of China(Grant No.2024YFB4504002)the National Natural Science Foundation of China(Grant No.92165107)。
文摘For the quantum error correction and noisy intermediate-scale quantum algorithms to function with high efficiency,the raw fidelity of quantum logic gates on physical qubits needs to satisfy strict requirements.The neutral atom quantum computing equipped with Rydberg blockade gates has made impressive progress recently,which makes it worthwhile to explore its potential in the two-qubit entangling gates,including the controlledphase gate,and in particular,the CZ gate.Provided the quantum coherence is well preserved,improving the fidelity of Rydberg blockade gates calls for special mechanisms to deal with adverse effects caused by realistic experimental conditions.Here,the heralded very-high-fidelity Rydberg blockade controlled-phase gate is designed to address these issues,which contains self-correction and projection as the key steps.This trailblazing method builds upon the previously established buffer-atom-mediated gate framework,with a special form of symmetry under parity–time transformation playing a crucial role in the process.We further analyze the performance with respect to a few typical sources of imperfections.This procedure can also be regarded as quantum hardware error correction or mitigation.While this paper by itself does not cover every single subtle issue and still contains many oversimplifications,we find it reasonable to anticipate a very-high-fidelity two-qubit quantum logic gate operated in the sense of heralded but probabilistic,whose gate error can be reduced to the level of 10^(-4)–10^(-6)or even lower with reasonably high possibilities.
基金supported by the National Natural Science Foundation of China(Grant Nos.12304401 and 12350006)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301200)USTC Research Funds of the Double First-Class Initiative(Grant No.YD2030002026)。
文摘Solid-state rare-earth ions are promising candidates for implementing repeater nodes for quantum networks.However,the state-of-the-art quantum nodes use only a single qubit per node,which greatly limits the functionality of the node and the scalability of the network.Here,we propose a scheme that utilizes a hybrid system of two ion qubits coupled to a nanophotonic cavity as a quantum node.Simultaneously applying a fast adiabatic pulse to the two ions can lead to an effective interaction between the two ion spin qubits by exchanging virtual photons in the cavity.Using this interaction,a controlled phase gate between the two ion qubits can be realized with a fidelity of 99.6%.Further utilizing this interaction,entangled states within the node can be generated deterministically with high fidelity,and are robust to a variety of noises and fluctuations.These results pave a way for fully functional quantum repeater nodes based on solid-state rare-earth ions.
基金supported by the Natural Science Foundation of Henan Province (No. 222300420233)。
文摘In this work, we propose a high-fidelity phonon-mediated entangling gate in a hybrid mechanical system based on two silicon-vacancy color centers in diamond. In order to suppress the influence of the spin decoherence on the entangling gate, we use a continuous dynamical decoupling approach to create new dressed spin states, which are less sensitive to environmental fluctuations and exhibit an extended T_(2)^(*) spin dephasing time. The effective spin-spin Hamiltonian modified by the mechanical driving field and the corresponding master equation are derived in the dispersive regime. We show that in the presence of the mechanical driving field, the effective spin-spin coupling can be highly controlled. By calculating the entangling gate fidelity in the dressed basis, we find that once the mechanical field is turned on, the gate fidelity can be significantly improved. In particular, under an optimized spin-phonon detuning and a stronger Rabi frequency of the mechanical driving field, the two-qubit gate is capable of reaching fidelity exceeding 0.99. Moreover, by employing appropriate driving modulation, we show that a highfidelity full quantum gate can be also realized, in which the initial and final spin states are on a bare basis. Our work provides a promising scheme for realizing high-fidelity quantum information processing.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974336 and 12304401)the National Key R&D Program of China(Grant No.2017YFA0304100)+1 种基金the Key Project of Natural Science Research in Universities of Anhui Province(Grant No.KJ2021A1107)the Scientific Research Foundation of Suzhou University(Grant Nos.2020BS006 and 2021XJPT18).
文摘Spin qubits and superconducting qubits are promising candidates for realizing solid-state quantum information processors.Designing a hybrid architecture that combines the advantages of different qubits on the same chip is a highly desirable but challenging goal.Here we propose a hybrid architecture that utilizes a high-impedance SQUID array resonator as a quantum bus,thereby coherently coupling different solid-state qubits.We employ a resonant exchange spin qubit hosted in a triple quantum dot and a superconducting transmon qubit.Since this hybrid system is highly tunable,it can operate in a dispersive regime,where the interaction between the different qubits is mediated by virtual photons.By utilizing such interactions,entangling gate operations between different qubits can be realized in a short time of 30 ns with a fidelity of up to 96.5%under realistic parameter conditions.Further utilizing this interaction,remote entangled state between different qubits can be prepared and is robust to perturbations of various parameters.These results pave the way for exploring efficient fault-tolerant quantum computation on hybrid quantum architecture platforms.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574092,61775062,61378012,91121023,and 60978009)the National Basic Research Program of China(Grant No.2013CB921804)
文摘We propose a novel scheme for generating the entanglement of two oscillating mirrors in an optomechanical system via a flying atom. In this scheme, a two-level atom, in an arbitrary superposition state, passes through an optomechanical system with two oscillating cavity-mirrors, and then its states are detected. In this way, we can generate the entangled states of the two oscillating mirrors. We derive the analytical expressions of the entangled states and make numerical calculations. We find that the entanglement of the two oscillating mirrors can be controlled by the initial state of the atom, the optomechanical coupling strength, and the coupling strength between the atom and the cavity field. We investigate the dynamics of the system with dissipations and discuss the experimental feasibility.
基金The project supported by National Natural Science Foundation of China under Grant No.10674025Funds from Fuzhou University
文摘A scheme is presented for the generation of entangled states for two cavity mirrors. In the scheme each mirror initially in a vacuum state interacts with a weak coherent field, resulting in a photon-number dependent kick. The detection of a photon leaking from the cavities collapses the two mirrors to an entangled state.
基金Project supported by the National Natural Science Foundation of China （Grant No 10574103）.
文摘Considering two light beams which are in general single-mode Gaussian states and incident on input ports of an ideal beam splitter, respectively, this paper investigates how separability and entanglement of the output lights depend on degrees of nonclassicality and purities of the input states. The minimum and maximum amounts of attainable entanglement in the output state are found
基金Project supported by the Natural Science Foundation of Anhui Province,China (Grant No. 090412060)the Natural Science Foundation of the Education Committee of Anhui Province,China (Grant No. KJ2008A029)
文摘A new scheme for quantum teleportation of single quantum bit state with using continuous variables entangling channel is presented. In our scheme two entangled light fields are employed. An outstanding characteristic of this scheme is that one atomic state is transmitted directly to another atom without using the third atom as the mediate.
基金National Natural Science Foundation of China under Grant No.10674025the Funds from Fuzhou University
文摘A scheme is presented for the generation of entangled states for two atoms trapped in two distant cavities. In the scheme each atom is resonantly coupled with the respective cavity mode and driven by a strong classical field. The detection of a photon decaying from the cavities and passing through a beam-splitter collapses the atoms to an entangled state. The required atom-field interaction time is very short and thus the decoherence effect is suppressed. Our scheme is within the reach of presently available cavity QED techniques.
基金Supported by the Doctoral Foundation of the Ministry of Education of China under Grant No.20093514110009
文摘We propose a scheme for the generation of two collections of atoms trapped in distant cavities connected by an optical fiber.The virtual photon exchange leads to the entanglement between these two atomic ensembles.During the operation the atomic system,cavity modes,and fiber are not excited,which is important in view of decoherence.
基金supported by National Natural Science Foundation of China under Grant Nos.10774042,10474118,and 1047200the National Fundamental Research Program of China under Grant No.2005CB724502
文摘A scheme has been proposed for generating the macroscopic entanglement between the mesoscopic squeezed vacuum states and mesoscopic coherent states by considering both the two-photon interaction and the single photon interaction of N two-level atoms in cavities with high quality factor assisted by a strong driving field. Moreover, we derive the dissipative interaction models for single photon interaction and two-photon interaction, respectively. The corresponding analytical expressions of the fidelities can be given. Our scheme can be realized in the current techniques on the cavity QED.
基金supported by the National Natural Science Foundation of China(Grant No.61771278)the Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘Limited by the thermal environment, the entanglement of a massive object is extremely difficult to generate. Based on a coherent scattering mechanism, we propose a scheme to generate the entanglement of two optically levitated nanospheres through the Coulomb interaction. Two nanospheres are charged and coupled to each other through the Coulomb interaction.In this manner, the entanglement of two nanospheres is induced either under a weak/strong optomechanical coupling regime or under an ultra-strong optomechanical coupling regime. The charges, radius and distance of the two nanospheres are taken into consideration to enhance the Coulomb interaction, thereby achieving a higher degree of entanglement in the absence of ground-state cooling. The corresponding maximum entanglement can be attained as the dynamics of the system approaches the boundary between the steady and the unsteady regimes. This provides a useful resource for both quantum-enhanced sensing and quantum information processing, as well as a new platform for studying many-body physics.
基金Supported by the National Natural Science Foundation of China(Grant Nos.90203018,10474104 and 60433050)the National FundamentalResearch Program of China(Grant Nos.2001CB309310 and 2005CB724508)
文摘The dynamic generation of spin entanglement between two distant sites in a XY model with 1/r 2 decay long-range couplings was studied.Due to the linear dispersion relationε(k)~|k|of magnons in such a model,a well-located spin state can be dynamically split into two moving entangled local wave packets without changing their shapes.Interestingly,when such two wave packets meet at the diametrically opposite site after the fast periodτ=Nπ/J,the initial well-located state is completely recurrent.Numerical calculation was performed to confirm the analytical result even if the ring system of sizes N up to several thousands is considered.The truncation approximation for the coupling strengths was also studied.Numerical simulation shows that the above conclusions still hold even if the range of the coupling strength is truncated to a relatively short scale compared with the size of the spin system.
基金supported by the National Natural Science Foundation of China(Grant Nos.12441502,12122506,12204230,and 12404554)the National Science and Technology Major Project of the Ministry of Science and Technology of China(2024ZD0300404)+6 种基金Guangdong Basic and Applied Basic Research Foundation(Grant No.2021B1515020070)Shenzhen Science and Technology Program(Grant No.RCYX20200714114522109)China Postdoctoral Science Foundation(CPSF)(2024M762114)Postdoctoral Fellowship Program of CPSF(GZC20231727)supported by the National Natural Science Foundation of China(Grant Nos.92165206 and 11974330)Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301603)the Fundamental Research Funds for the Central Universities。
文摘We present a robust quantum optimal control framework for implementing fast entangling gates on ion-trap quantum processors.The framework leverages tailored laser pulses to drive the multiple vibrational sidebands of the ions to create phonon-mediated entangling gates and,unlike the state of the art,requires neither weakcoupling Lamb-Dicke approximation nor perturbation treatment.With the application of gradient-based optimal control,it enables finding amplitude-and phase-modulated laser control protocols that work without the Lamb-Dicke approximation,promising gate speeds on the order of microseconds comparable to the characteristic trap frequencies.Also,robustness requirements on the temperature of the ions and initial optical phase can be conveniently included to pursue high-quality fast gates against experimental imperfections.Our approach represents a step in speeding up quantum gates to achieve larger quantum circuits for quantum computation and simulation,and thus can find applications in near-future experiments.
基金supported by the National Key Research&Development Program of China(grant no.2022YFC3500503)the National Natural Science Foundation of China(grant nos.62227807,12374171,12004034,62402041)+2 种基金the Beijing Institute of Technology Research Fund Program for Young Scholars,Chinathe Fundamental Research Funds for the Central Universities(grant nos.2024CX06060)Beijing Youth Talent Lifting Project.
文摘Due to their high mechanical compliance and excellent biocompatibility,conductive hydrogels exhibit significant potential for applications in flexible electronics.However,as the demand for high sensitivity,superior mechanical properties,and strong adhesion performance continues to grow,many conventional fabrication methods remain complex and costly.Herein,we propose a simple and efficient strategy to construct an entangled network hydrogel through a liquid-metal-induced cross-linking reaction,hydrogel demonstrates outstanding properties,including exceptional stretchability(1643%),high tensile strength(366.54 kPa),toughness(350.2 kJ m^(−3)),and relatively low mechanical hysteresis.The hydrogel exhibits long-term stable reusable adhesion(104 kPa),enabling conformal and stable adhesion to human skin.This capability allows it to effectively capture high-quality epidermal electrophysiological signals with high signal-to-noise ratio(25.2 dB)and low impedance(310 ohms).Furthermore,by integrating advanced machine learning algorithms,achieving an attention classification accuracy of 91.38%,which will significantly impact fields like education,healthcare,and artificial intelligence.
基金Project supported by the Open Fund of Anhui Key Laboratory of Mine Intelligent Equipment and Technology (Grant No. ZKSYS202204)the Talent Introduction Fund of Anhui University of Science and Technology (Grant No. 2021yjrc34)the Scientific Research Fund of Anhui Provincial Education Department (Grant No. KJ2020A0301)。
文摘Implementing quantum wireless multi-hop network communication is essential to improve the global quantum network system. In this paper, we employ eight-level GHZ states as quantum channels to realize multi-hop quantum communication, and utilize the logical relationship between the measurements of each node to derive the unitary operation performed by the end node. The hierarchical simultaneous entanglement switching(HSES) method is adopted, resulting in a significant reduction in the consumption of classical information compared to multi-hop quantum teleportation(QT)based on general simultaneous entanglement switching(SES). In addition, the proposed protocol is simulated on the IBM Quantum Experiment platform(IBM QE). Then, the data obtained from the experiment are analyzed using quantum state tomography, which verifies the protocol's good fidelity and accuracy. Finally, by calculating fidelity, we analyze the impact of four different types of noise(phase-damping, amplitude-damping, phase-flip and bit-flip) in this protocol.
文摘The no-cloning theorem has sparked considerable interest in achieving high-fidelity approximate quantum cloning.Most of the previous studies mainly focused on the cloning of single particle states,and cloning schemes used there are incapable of cloning quantum entangled states in multipartite systems.Few schemes were proposed for cloning multiparticle states,which consume more entanglement resources with loss of qubits,and the fidelity of the cloned state is relatively low.In this paper,cloning schemes for bipartite and tripartite entangled states based on photonic quantum walk and entanglement swapping are proposed.The results show that according to the proposed schemes,two high-fidelity(up to 0.75)cloned states can be obtained with less quantum resource consumption.Because of the simple cloning steps,few quantum resources and high fidelity,these schemes are both efficient and feasible.Moreover,this cloning machine eliminates the need for tracing out cloning machine,thereby minimizing resource waste.
基金supported by the the National Natural Science Foundation of China(Grant Nos.12175015 for W.G.and 12174387 for L.Z.)the Chinese Academy of Sciences (Grant Nos.YSBR-057 and JZHKYPT-2021-08 for L.Z.)+1 种基金the Innovative Program for Quantum Science and Technology (Grant No.2021ZD0302600 for L.Z.)the start-up funding of Westlake University and the China Postdoctoral Science Foundation (Grant No.2024M752898 for Z.W.and Z.Y.)。
文摘Entanglement plays a key role in quantum physics, but how much information it can extract from many-body systems is still an open question, particularly regarding quantum criticalities and emergent symmetries. In this work, we systematically study the entanglement entropy(EE) and derivative entanglement entropy(DEE) near quantum phase transitions in various quantum many-body systems. A one-parameter scaling relation between the DEE and system size at the critical point has been derived for the first time, which successfully obtains the critical exponent via data collapse. Furthermore, we find that the EE peaks at the(emergent) symmetryenhanced first-order transition, reflecting higher symmetry breaking. This work provides a new paradigm for quantum many-body research from the perspective of EE and DEE.
基金supported by the National Natural Science Foundation of China (Grant Nos.12274273and 12450402)the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0302101)。
文摘The rapid advancements of ultrafast intense laser technology have opened new avenues for investigating entanglement in laser-induced systems. However, the application of these advances in quantum technology requires a reliable and universally applicable method for enhancing and regulating entanglement. Here we demonstrate how a few-cycle intense laser field can significantly enhance the degree of entanglement compared to its multi-cycle counterpart, using the example of electron–electron entanglement of orbital angular momentum(OAM) states in recollision-excitation non-sequential double ionization of Ar atoms. By confining the ionization dynamics to a specific narrow time window, the few-cycle pulse purifies the electron trajectories, thereby ensuring high coherence between entangled OAM channels and enhancing entanglement. Furthermore, the degree of entanglement can be efficiently modulated by varying the carrier envelope phase of the few-cycle laser pulse, which is achieved by altering the population across OAM channels. Optimizing coherence through electron trajectory purification with a designed specific temporal waveform of laser field provides a general pathway for enhancing entanglement in laser-induced systems.
基金The derivation of the population coefficients in the emission induced by a plane wave are supported by the Foundation for the Advancement of Theoretical Physics and Mathematics“BASIS”The extension of these calculations to an incident vortex photon is supported by the Ministry of Science and Higher Education of the Russian Federation(Grant No.FSER-2025-0012)+2 种基金The studies of time dynamics of OAM of the entangled pair are supported by the Russian Science Foundation(Grant No.23-62-10026https://rscf.ru/en/project/23-6210026/)The studies of influence of the finite localization region of an atom on its interaction with an incident vortex photons are supported by the Russian Science Foundation(Grant No.25-71-00060)。
文摘Pairs of entangled vortex photons can promise new prospects of application in quantum computing and cryptography.We investigate the possibility of generating such states via two-level atom emission induced by a single photon wave packet with a definite total angular momentum(TAM).The entangled pair produced in this process possesses well-defined mean TAM with the TAM variation being much smaller than h.On top of that,the variation exponentially decreases with the increase in TAM of the incident photon.Our model allows one to track the time evolution of the state of the entangled pair.An experimentally feasible scenario is assumed,in which the incident photon interacts with a spatially confined atomic target.We conclude that induced emission can be used as a source of entangled vortex photons with applications in atomic physics experiments,quantum optics,and quantum information sciences.
