We propose a simple and fast scheme to realize a controlled-NOT gate between two trapped ions using a resonant laser pulse. Our scheme allows the Rabi frequency of the laser field to be of the order of the vibrational...We propose a simple and fast scheme to realize a controlled-NOT gate between two trapped ions using a resonant laser pulse. Our scheme allows the Rabi frequency of the laser field to be of the order of the vibrational frequency and thus the time required to complete the operation is greatly shortened, which is of importance in view of decoherence.展开更多
We present a scheme to realize the basic two-qubit logic gates such as the quantum phase gate and SWAP gate using a detuned microwave cavity interacting with three-level superconducting-quantum-interference-device （S...We present a scheme to realize the basic two-qubit logic gates such as the quantum phase gate and SWAP gate using a detuned microwave cavity interacting with three-level superconducting-quantum-interference-device （SQUID） qubit（s）, by placing SQUID（s） in a two-mode microwave cavity and using adiabatic passage methods. In this scheme, the two logical states of the qubit are represented by the two lowest levels of the SQUID, and the cavity fields are treated as quantized. Compared with the previous method, the complex procedures of adjusting tile level spacing of the SQUID and applying the resonant microwave pulse to the SQUID to create transformation are not required. Based on superconducting device with relatively long decoherence time and simplified operation procedure, the gates operate at a high speed, which is important in view of decoherence.展开更多
A scheme is presented for realizing quantum logic gates for two atoms localized in two distant optical cavities. Our scheme works in a regime in which the atom-cavity coupling strength is smaller than the cavity decay...A scheme is presented for realizing quantum logic gates for two atoms localized in two distant optical cavities. Our scheme works in a regime in which the atom-cavity coupling strength is smaller than the cavity decay rate. Thus the requirement on the quality factor of the cavities is greatly relaxed. Furthermore, the fidelity of our scheme is not affected by detection inefficiency and atomic decay. These advantages are important in view of experiment.展开更多
Connectivity of two-qubit logic gates plays a crucial and indispensable role in quantum computation research.For the cold atom qubit platform,while the two-qubit Rydberg blockade gate has recently made rapid experimen...Connectivity of two-qubit logic gates plays a crucial and indispensable role in quantum computation research.For the cold atom qubit platform,while the two-qubit Rydberg blockade gate has recently made rapid experimental progress,a pressing challenge is to improve connectivity in pursuit of genuine scalability without sacrificing speed or fidelity.A significant advancement in this direction can be achieved by introducing an extra buffer atom to extend the two-qubit gate beyond purely nearest-neighbor two-body interactions.The buffer atom couples with the two qubit atoms through nearest-neighbor interactions,even though the qubit atoms do not directly exert any physical influence on each other.The established method of off-resonant modulated driving(ORMD)is not only convenient but also lays the groundwork for this latest development.Although the atomic linkage structure here exhibits more complex interactions compared to previous two-body systems,the population can satisfactorily return to the ground state after the ground-Rydberg transition with a properly designed modulation waveform.This can be achieved through one-photon and two-photon ground-Rydberg transitions in common practices.Furthermore,with buffer atom relay or similar structures,it is possible to realize a two-qubit entangling gate between two distant qubit atoms.In addition to demonstrating that such solutions are feasible,the representative modulation patterns are analyzed,showcasing the versatility of buffer-atom-mediated two-qubit gates.From a broader perspective,these efforts enhance the resemblance between the cold atom qubit platform and the superconducting qubit system,with the buffer atom functioning like wires and junctions.展开更多
We propose a scheme for implementation of a universal set of quantum logic gates in decoherence-free subspace with atoms trapped in distant cavities connected by optical fibers.The selective dispersive couplings betwe...We propose a scheme for implementation of a universal set of quantum logic gates in decoherence-free subspace with atoms trapped in distant cavities connected by optical fibers.The selective dispersive couplings between the ground states and the first-excited states of the atom-cavity-fiber system produce a state-dependent Stark shift,which can be used to implement nonlocal phase gates between two logic qubits.The single-logic-qubit quantum gates are achieved by the local two-atom collision and the Stark shift of a single atom.During all the logic operations,the logic qubits remain in decoherence-free subspace and thus the operation is immune to collective dephasing.展开更多
Based on the coupling of two distant three-level atoms in two separate optical cavities connected with two optical fibres, schemes on the generation of several two-qubit logic gates are discussed under the conditions ...Based on the coupling of two distant three-level atoms in two separate optical cavities connected with two optical fibres, schemes on the generation of several two-qubit logic gates are discussed under the conditions of △ = δ- 2v cos πk/2 〉〉 g/2 and v-g. Discussion and analysis of the fidelity, gate time and experimental setups show that our schemes are feasible with current optical cavity, atomic trap and optical fibre techniques. Moreover, the atom-cavityfibre coupling can be used to generate an N-qubit nonlocal entanglement and transfer quantum information among N distant atoms by arranging N atom cavity assemblages in a line and connecting each two adjacent cavities with two optical fibres.展开更多
This paper briefly introduces the five types of the surgical operations in knot theory and obtains the expression of single qubit quantum logic gate in terms of these surgical operations.
We propose a scheme for implementing nongeometric phase gates fbr two trapped ions via adiabatic passage of dark states. During the operation, the vibrational mode is only virtually excited, thus the scheme is insensi...We propose a scheme for implementing nongeometric phase gates fbr two trapped ions via adiabatic passage of dark states. During the operation, the vibrational mode is only virtually excited, thus the scheme is insensitive to heating. Furthermore, the spontaneous emission is suppressed since the ions are always in the electronic ground states. The scheme is robust against small fluctuations of parameters, and the conditional phase is tunable.展开更多
This paper proposes a simple scheme for realizing one-qubit and two-qubit quantum gates as well as multiqubit entanglement based on de-SQUID charge qubits through the control of their coupling to a 1D transmission lin...This paper proposes a simple scheme for realizing one-qubit and two-qubit quantum gates as well as multiqubit entanglement based on de-SQUID charge qubits through the control of their coupling to a 1D transmission line resonator （TLR）. The TLR behaves effectively as a quantum data-bus mode of a harmonic oscillator, which has several practical advantages including strong coupling strength, reproducibility, immunity to 1/f noise, and suppressed spontaneous emission. In this protocol, the data-bus does not need to stay adiabatically in its ground state, which results in not only fast quantum operation, hut also high-fidelity quantum information processing. Also, it elaborates the transfer process with the 1D transmission line.展开更多
In this paper,we do research on generating unitary matrices for quantum circuits automatically.We consider that quantum circuits are divided into six types,and the unitary operator expressions for each type are offere...In this paper,we do research on generating unitary matrices for quantum circuits automatically.We consider that quantum circuits are divided into six types,and the unitary operator expressions for each type are offered.Based on this,we propose an algorithm for computing the circuit unitary matrices in detail.Then,for quantum logic circuits composed of quantum logic gates,a faster method to compute unitary matrices of quantum circuits with truth table is introduced as a supplement.Finally,we apply the proposed algorithm to different reversible benchmark circuits based on NCT library(including NOT gate,Controlled-NOT gate,Toffoli gate)and generalized Toffoli(GT)library and provide our experimental results.展开更多
In this letter, by using the method we offered in our paper [L. Ma and Y.D. Zhang, Commun. Theor. Phys.(Beijing, China) 36 (2001) 119], some extended quantum logic gates, such as quantum counter, quantum adder, are st...In this letter, by using the method we offered in our paper [L. Ma and Y.D. Zhang, Commun. Theor. Phys.(Beijing, China) 36 (2001) 119], some extended quantum logic gates, such as quantum counter, quantum adder, are studied and their expressions are given. It may be useful for us to study the more complicated quantum logic circuits deeply.展开更多
We propose a scheme to construct the multiple-qubit Rydberg quantum controlled-phase gate with one control and multiple target qubits. The proposed quantum logic gate works under the asymmetric-Rydberg-interaction-ind...We propose a scheme to construct the multiple-qubit Rydberg quantum controlled-phase gate with one control and multiple target qubits. The proposed quantum logic gate works under the asymmetric-Rydberg-interaction-induced dipole blockade and can be implemented with three operation steps. The most prominent characteristic of the scheme is that the required operation time and steps keep invariant as the number of qubits increases. The Rydberg state leakage and some practical situations are considered. The Lindblad master equation is used to evaluate and verify the feasibility of the scheme.展开更多
The traditional method for information transfer in a quantum communication system using partially entangled state resource is quantum distillation or direct teleportation. In order to reduce the waiting time cost in h...The traditional method for information transfer in a quantum communication system using partially entangled state resource is quantum distillation or direct teleportation. In order to reduce the waiting time cost in hop-by-hop transmission and execute independently in each node, we propose a quantum bridging method with partially entangled states to teleport quantum states from source node to destination node. We also prove that the designed specific quantum bridging circuit is feasible for partially entangled states teleportation across multiple intermediate nodes. Compared to two traditional ways, our partially entanglement quantum bridging method uses simpler logic gates, has better security, and can be used in less quantum resource situation.展开更多
Overlaying commensurate optical lattices with various configurations called superlattices can lead to exotic lattice topologies and, in turn, a discovery of novel physics. In this study, by overlapping the maxima of l...Overlaying commensurate optical lattices with various configurations called superlattices can lead to exotic lattice topologies and, in turn, a discovery of novel physics. In this study, by overlapping the maxima of lattices, a new isolated structure is created, while the interference of minima can generate various ＂sublattice＂ patterns. Three different kinds of primitive lattices are used to demonstrate isolated square, triangular, and hexagonal ＂sublattice＂ structures in a two-dimensional optical superlattice, the patterns of which can be manipulated dynamically by tuning the polarization, frequency, and intensity of laser beams. In addition, we propose the method of altering the relative phase to adjust the tunneling amplitudes in ＂sublattices＇. Our configurations provide unique opportunities to study particle entanglement in ＂lattices＂ formed by intersecting wells and to implement special quantum logic gates in exotic lattice geometries.展开更多
基金The project supported by Fok Ying Tung Education Foundation under Grant No.81008+4 种基金National Natural Science Foundation of China under Grant No.60008003Natural Science Foundation of Fujian Province of China under Grant Nos.K20004 and F0110027the Funds from Fuzhou University
文摘We propose a simple and fast scheme to realize a controlled-NOT gate between two trapped ions using a resonant laser pulse. Our scheme allows the Rabi frequency of the laser field to be of the order of the vibrational frequency and thus the time required to complete the operation is greatly shortened, which is of importance in view of decoherence.
文摘We present a scheme to realize the basic two-qubit logic gates such as the quantum phase gate and SWAP gate using a detuned microwave cavity interacting with three-level superconducting-quantum-interference-device （SQUID） qubit（s）, by placing SQUID（s） in a two-mode microwave cavity and using adiabatic passage methods. In this scheme, the two logical states of the qubit are represented by the two lowest levels of the SQUID, and the cavity fields are treated as quantized. Compared with the previous method, the complex procedures of adjusting tile level spacing of the SQUID and applying the resonant microwave pulse to the SQUID to create transformation are not required. Based on superconducting device with relatively long decoherence time and simplified operation procedure, the gates operate at a high speed, which is important in view of decoherence.
基金supported by the Doctoral Foundation of the Ministry of Education of China(Grant No 20070386002)
文摘A scheme is presented for realizing quantum logic gates for two atoms localized in two distant optical cavities. Our scheme works in a regime in which the atom-cavity coupling strength is smaller than the cavity decay rate. Thus the requirement on the quality factor of the cavities is greatly relaxed. Furthermore, the fidelity of our scheme is not affected by detection inefficiency and atomic decay. These advantages are important in view of experiment.
基金supported by the National Natural Science Foundation of China(Grant Nos.92165107,and 12074391)the Fundamental Research Program of the Chinese Academy of Sciencesthe Science and Technology Commission of Shanghai Municipality。
文摘Connectivity of two-qubit logic gates plays a crucial and indispensable role in quantum computation research.For the cold atom qubit platform,while the two-qubit Rydberg blockade gate has recently made rapid experimental progress,a pressing challenge is to improve connectivity in pursuit of genuine scalability without sacrificing speed or fidelity.A significant advancement in this direction can be achieved by introducing an extra buffer atom to extend the two-qubit gate beyond purely nearest-neighbor two-body interactions.The buffer atom couples with the two qubit atoms through nearest-neighbor interactions,even though the qubit atoms do not directly exert any physical influence on each other.The established method of off-resonant modulated driving(ORMD)is not only convenient but also lays the groundwork for this latest development.Although the atomic linkage structure here exhibits more complex interactions compared to previous two-body systems,the population can satisfactorily return to the ground state after the ground-Rydberg transition with a properly designed modulation waveform.This can be achieved through one-photon and two-photon ground-Rydberg transitions in common practices.Furthermore,with buffer atom relay or similar structures,it is possible to realize a two-qubit entangling gate between two distant qubit atoms.In addition to demonstrating that such solutions are feasible,the representative modulation patterns are analyzed,showcasing the versatility of buffer-atom-mediated two-qubit gates.From a broader perspective,these efforts enhance the resemblance between the cold atom qubit platform and the superconducting qubit system,with the buffer atom functioning like wires and junctions.
基金supported by the Major State Basic Research Development Program of China (Grant No. 2012CB921601)the National Natural Science Foundation of China (Grant No. 10974028)+1 种基金the Doctoral Foundation of the Ministry of Education of China (Grant No. 20093514110009)the Natural Science Foundation of Fujian Province (Grant No. 2009J06002)
文摘We propose a scheme for implementation of a universal set of quantum logic gates in decoherence-free subspace with atoms trapped in distant cavities connected by optical fibers.The selective dispersive couplings between the ground states and the first-excited states of the atom-cavity-fiber system produce a state-dependent Stark shift,which can be used to implement nonlocal phase gates between two logic qubits.The single-logic-qubit quantum gates are achieved by the local two-atom collision and the Stark shift of a single atom.During all the logic operations,the logic qubits remain in decoherence-free subspace and thus the operation is immune to collective dephasing.
文摘Based on the coupling of two distant three-level atoms in two separate optical cavities connected with two optical fibres, schemes on the generation of several two-qubit logic gates are discussed under the conditions of △ = δ- 2v cos πk/2 〉〉 g/2 and v-g. Discussion and analysis of the fidelity, gate time and experimental setups show that our schemes are feasible with current optical cavity, atomic trap and optical fibre techniques. Moreover, the atom-cavityfibre coupling can be used to generate an N-qubit nonlocal entanglement and transfer quantum information among N distant atoms by arranging N atom cavity assemblages in a line and connecting each two adjacent cavities with two optical fibres.
文摘This paper briefly introduces the five types of the surgical operations in knot theory and obtains the expression of single qubit quantum logic gate in terms of these surgical operations.
基金Supported by the National Natural Science Foundation of China under Grant No 10225421, and the Fund from Fuzhou University.
文摘We propose a scheme for implementing nongeometric phase gates fbr two trapped ions via adiabatic passage of dark states. During the operation, the vibrational mode is only virtually excited, thus the scheme is insensitive to heating. Furthermore, the spontaneous emission is suppressed since the ions are always in the electronic ground states. The scheme is robust against small fluctuations of parameters, and the conditional phase is tunable.
基金supported by Hunan Provincial Natural Science Foundation of China (Grant No 06JJ50014)the Key Project Foundation of the Education Commission of Hunan Province of China (Grant No 06A055)
文摘This paper proposes a simple scheme for realizing one-qubit and two-qubit quantum gates as well as multiqubit entanglement based on de-SQUID charge qubits through the control of their coupling to a 1D transmission line resonator （TLR）. The TLR behaves effectively as a quantum data-bus mode of a harmonic oscillator, which has several practical advantages including strong coupling strength, reproducibility, immunity to 1/f noise, and suppressed spontaneous emission. In this protocol, the data-bus does not need to stay adiabatically in its ground state, which results in not only fast quantum operation, hut also high-fidelity quantum information processing. Also, it elaborates the transfer process with the 1D transmission line.
基金This work was funded by the Natural Science Foundation of Jiangsu Province(Grant No:BK20171458)the Yangzhou University International Academic Exchange Fund.
文摘In this paper,we do research on generating unitary matrices for quantum circuits automatically.We consider that quantum circuits are divided into six types,and the unitary operator expressions for each type are offered.Based on this,we propose an algorithm for computing the circuit unitary matrices in detail.Then,for quantum logic circuits composed of quantum logic gates,a faster method to compute unitary matrices of quantum circuits with truth table is introduced as a supplement.Finally,we apply the proposed algorithm to different reversible benchmark circuits based on NCT library(including NOT gate,Controlled-NOT gate,Toffoli gate)and generalized Toffoli(GT)library and provide our experimental results.
文摘In this letter, by using the method we offered in our paper [L. Ma and Y.D. Zhang, Commun. Theor. Phys.(Beijing, China) 36 (2001) 119], some extended quantum logic gates, such as quantum counter, quantum adder, are studied and their expressions are given. It may be useful for us to study the more complicated quantum logic circuits deeply.
基金Project supported by the National Natural Science Foundation of China(Grant No.11747096)
文摘We propose a scheme to construct the multiple-qubit Rydberg quantum controlled-phase gate with one control and multiple target qubits. The proposed quantum logic gate works under the asymmetric-Rydberg-interaction-induced dipole blockade and can be implemented with three operation steps. The most prominent characteristic of the scheme is that the required operation time and steps keep invariant as the number of qubits increases. The Rydberg state leakage and some practical situations are considered. The Lindblad master equation is used to evaluate and verify the feasibility of the scheme.
文摘The traditional method for information transfer in a quantum communication system using partially entangled state resource is quantum distillation or direct teleportation. In order to reduce the waiting time cost in hop-by-hop transmission and execute independently in each node, we propose a quantum bridging method with partially entangled states to teleport quantum states from source node to destination node. We also prove that the designed specific quantum bridging circuit is feasible for partially entangled states teleportation across multiple intermediate nodes. Compared to two traditional ways, our partially entanglement quantum bridging method uses simpler logic gates, has better security, and can be used in less quantum resource situation.
基金Acknowledgements This work was supported by the National Key Research and Development Program of China （Grant No. 2016YFA0301501）, and the National Natural Science Foundation of China （Grants Nos. 61475007, 11334001, and 91336103）.
文摘Overlaying commensurate optical lattices with various configurations called superlattices can lead to exotic lattice topologies and, in turn, a discovery of novel physics. In this study, by overlapping the maxima of lattices, a new isolated structure is created, while the interference of minima can generate various ＂sublattice＂ patterns. Three different kinds of primitive lattices are used to demonstrate isolated square, triangular, and hexagonal ＂sublattice＂ structures in a two-dimensional optical superlattice, the patterns of which can be manipulated dynamically by tuning the polarization, frequency, and intensity of laser beams. In addition, we propose the method of altering the relative phase to adjust the tunneling amplitudes in ＂sublattices＇. Our configurations provide unique opportunities to study particle entanglement in ＂lattices＂ formed by intersecting wells and to implement special quantum logic gates in exotic lattice geometries.
