The Experts below are selected from a list of 117 Experts worldwide ranked by ideXlab platform
Chui-ping Yang - One of the best experts on this subject based on the ideXlab platform.
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implementing a multi Target Qubit controlled not gate with logical Qubits outside a decoherence free subspace and its application in creating quantum entangled states
Physical Review A, 2020Co-Authors: Chui-ping Yang, Yu Zhang, Franco NoriAbstract:In general, implementing a multi-logical-Qubit gate by manipulating quantum states in a decoherence-free subspace (DFS) becomes more complex and difficult when increasing the number of logical Qubits. In this work, we propose an idea to realize quantum gates by manipulating quantum states outside their DFS but having the states of the logical Qubits remain in their DFS before and after the gate operation. This proposal has the following features: (i) because the states are manipulated outside the DFS, the multiQubit gate implementation can be simplified when compared to realizing a multiQubit gate via manipulating quantum states within the DFS, which usually requires unitary operations over a large DFS, and (ii) because the states of the logical Qubits return to the DFS after the gate operation, the errors caused by decoherence during the gate operation are not accumulated for a long-running calculation, and the states of the logical Qubits are immune to decoherence when they are stored. Based on this proposal, we then present a way for realizing a multi-Target-Qubit controlled-not gate using logical Qubits encoded in a decoherence-free subspace against collective dephasing. This gate is realized by employing qutrits (three-level quantum systems) placed in a cavity or coupled to a resonator. This proposal has the following advantages: (i) the states of the logical Qubits return to their DFS after the gate operation; (ii) the gate can be implemented with only a few basic operations; (iii) the gate operation time is independent of the number of logical Qubits; (iv) this gate can be deterministically implemented because no measurement is needed; (v) the intermediate higher-energy level for all qutrits is not occupied during the entire operation, thus decoherence from this level is greatly suppressed; (vi) this proposal is universal and can be applied to realize the proposed gate using natural atoms or artificial atoms (e.g., quantum dots, nitrogen-vacancy centers, and various superconducting qutrits, etc.) placed in a cavity or coupled to a resonator. As an application, we also show how to apply this gate to create a Greenberger-Horne-Zeilinger (GHZ) entangled state of multiple logical Qubits encoded in DFS, and further investigate the experimental feasibility for creating the GHZ state of three logical Qubits in the DFS, by using six superconducting transmon qutrits coupled to a one-dimensional coplanar waveguide resonator.
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one step implementation of a multi Target Qubit controlled phase gate with cat state Qubits in circuit qed
arXiv: Quantum Physics, 2019Co-Authors: Youji Fan, Chui-ping Yang, Yu Zhang, Zhenfei ZhengAbstract:We propose a single-step implementation of a muti-Target-Qubit controlled phase gate with one cat-state Qubit (\textit{cQubit}) simultaneously controlling $n-1$ Target \textit{cQubits}. The two logic states of a \textit{cQubit} are represented by two orthogonal cat states of a single cavity mode. In this proposal, the gate is implemented with $n$ microwave cavities coupled to a superconducting transmon qutrit. Because the qutrit remains in the ground state during the gate operation, decoherence caused due to the qutrit's energy relaxation and dephasing is greatly suppressed. The gate implementation is quite simple because only a single-step operation is needed and neither classical pulse nor measurement is required. Numerical simulations demonstrate that high-fidelity realization of a controlled phase gate with one cQubit simultaneously controlling two Target cQubits is feasible with present circuit QED technology. This proposal can be extended to a wide range of physical systems to realize the proposed gate, such as multiple microwave or optical cavities coupled to a natural or artificial three-level atom.
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circuit qed single step realization of a multiQubit controlled phase gate with one microwave photonic Qubit simultaneously controlling n 1 microwave photonic Qubits
arXiv: Quantum Physics, 2019Co-Authors: Zhenfei Zheng, Yu Zhang, Chui-ping YangAbstract:We present a novel method to realize a multi-Target-Qubit controlled phase gate with one microwave photonic Qubit simultaneously controlling $n-1$ Target microwave photonic Qubits. This gate is implemented with $n$ microwave cavities coupled to a superconducting flux qutrit. Each cavity hosts a microwave photonic Qubit, whose two logic states are represented by the vacuum state and the single photon state of a single cavity mode, respectively. During the gate operation, the qutrit remains in the ground state and thus decoherence from the qutrit is greatly suppressed. This proposal requires only a single-step operation and thus the gate implementation is quite simple. The gate operation time is independent of the number of the Qubits. In addition, this proposal does not need applying classical pulse or any measurement. Numerical simulations demonstrate that high-fidelity realization of a controlled phase gate with one microwave photonic Qubit simultaneously controlling two Target microwave photonic Qubits is feasible with current circuit QED technology. The proposal is quite general and can be applied to implement the proposed gate in a wide range of physical systems, such as multiple microwave or optical cavities coupled to a natural or artificial $\Lambda$-type three-level atom.
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one step implementation of a multi Target Qubit controlled phase gate with cat state Qubits in circuit qed
Frontiers of Physics in China, 2019Co-Authors: Youji Fan, Chui-ping Yang, Yu Zhang, Zhenfei ZhengAbstract:We propose a single-step implementation of a muti-Target-Qubit controlled phase gate with one catstate Qubit (cQubit) simultaneously controlling n–1 Target cQubits. The two logic states of a cQubit are represented by two orthogonal cat states of a single cavity mode. In this proposal, the gate is implemented with n microwave cavities coupled to a superconducting transmon qutrit. Because the qutrit remains in the ground state during the gate operation, decoherence caused due to the qutrit’s energy relaxation and dephasing is greatly suppressed. The gate implementation is quite simple because only a single-step operation is needed and neither classical pulse nor measurement is required. Numerical simulations demonstrate that high-fidelity realization of a controlled phase gate with one cQubit simultaneously controlling two Target cQubits is feasible with present circuit QED technology. This proposal can be extended to a wide range of physical systems to realize the proposed gate, such as multiple microwave or optical cavities coupled to a natural or artificial three-level atom.
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Multi-Target-Qubit unconventional geometric phase gate in a multi-cavity system
Scientific Reports, 2016Co-Authors: Qi-ping Su, Shao-jie Xiong, Chui-ping YangAbstract:: Cavity-based large scale quantum information processing (QIP) may involve multiple cavities and require performing various quantum logic operations on Qubits distributed in different cavities. Geometric-phase-based quantum computing has drawn much attention recently, which offers advantages against inaccuracies and local fluctuations. In addition, multiQubit gates are particularly appealing and play important roles in QIP. We here present a simple and efficient scheme for realizing a multi-Target-Qubit unconventional geometric phase gate in a multi-cavity system. This multiQubit phase gate has a common control Qubit but different Target Qubits distributed in different cavities, which can be achieved using a single-step operation. The gate operation time is independent of the number of Qubits and only two levels for each Qubit are needed. This multiQubit gate is generic, e.g., by performing single-Qubit operations, it can be converted into two types of significant multi-Target-Qubit phase gates useful in QIP. The proposal is quite general, which can be used to accomplish the same task for a general type of Qubits such as atoms, NV centers, quantum dots, and superconducting Qubits.
Franco Nori - One of the best experts on this subject based on the ideXlab platform.
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implementing a multi Target Qubit controlled not gate with logical Qubits outside a decoherence free subspace and its application in creating quantum entangled states
Physical Review A, 2020Co-Authors: Chui-ping Yang, Yu Zhang, Franco NoriAbstract:In general, implementing a multi-logical-Qubit gate by manipulating quantum states in a decoherence-free subspace (DFS) becomes more complex and difficult when increasing the number of logical Qubits. In this work, we propose an idea to realize quantum gates by manipulating quantum states outside their DFS but having the states of the logical Qubits remain in their DFS before and after the gate operation. This proposal has the following features: (i) because the states are manipulated outside the DFS, the multiQubit gate implementation can be simplified when compared to realizing a multiQubit gate via manipulating quantum states within the DFS, which usually requires unitary operations over a large DFS, and (ii) because the states of the logical Qubits return to the DFS after the gate operation, the errors caused by decoherence during the gate operation are not accumulated for a long-running calculation, and the states of the logical Qubits are immune to decoherence when they are stored. Based on this proposal, we then present a way for realizing a multi-Target-Qubit controlled-not gate using logical Qubits encoded in a decoherence-free subspace against collective dephasing. This gate is realized by employing qutrits (three-level quantum systems) placed in a cavity or coupled to a resonator. This proposal has the following advantages: (i) the states of the logical Qubits return to their DFS after the gate operation; (ii) the gate can be implemented with only a few basic operations; (iii) the gate operation time is independent of the number of logical Qubits; (iv) this gate can be deterministically implemented because no measurement is needed; (v) the intermediate higher-energy level for all qutrits is not occupied during the entire operation, thus decoherence from this level is greatly suppressed; (vi) this proposal is universal and can be applied to realize the proposed gate using natural atoms or artificial atoms (e.g., quantum dots, nitrogen-vacancy centers, and various superconducting qutrits, etc.) placed in a cavity or coupled to a resonator. As an application, we also show how to apply this gate to create a Greenberger-Horne-Zeilinger (GHZ) entangled state of multiple logical Qubits encoded in DFS, and further investigate the experimental feasibility for creating the GHZ state of three logical Qubits in the DFS, by using six superconducting transmon qutrits coupled to a one-dimensional coplanar waveguide resonator.
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multiQubit tunable phase gate of one Qubit simultaneously controlling n Qubits in a cavity
Physical Review A, 2010Co-Authors: Chui-ping Yang, Shi-biao Zheng, Franco NoriAbstract:We propose how to realize a multiQubit tunable phase gate of one Qubit simultaneously controlling $n$ Qubits with four-level quantum systems in a cavity or coupled to a resonator. Each of the $n$ two-Qubit controlled-phase (cp) gates involved in this multiQubit phase gate has a shared control Qubit but a different Target Qubit. In this proposal, the two lowest levels of each system represent the two logical states of a Qubit while the two higher-energy intermediate levels are used for the gate implementation. The method presented here operates essentially by creating a single photon through the control Qubit, which then induces a phase shift to the state of each Target Qubit. The phase shifts on each Target Qubit can be adjusted by changing the Rabi frequencies of the pulses applied to the Target Qubit systems. The operation time for the gate implementation is independent of the number of Qubits, and neither adjustment of the Qubit level spacings nor adjustment of the cavity mode frequency during the gate operation is required by this proposal. It is also noted that this approach can be applied to implement certain types of significant multiQubit phase gates (e.g., the multiQubit phase gate consisting of $n$ two-Qubit cp gates which are key elements in quantum Fourier transforms). A possible physical implementation of our approach is presented. Our proposal is quite general and can be applied to physical systems such as various types of superconducting devices coupled to a resonator and trapped atoms in a cavity.
Hong-fu Wang - One of the best experts on this subject based on the ideXlab platform.
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a scheme for direct implementation of a two Target Qubit controlled phase gate with quantum dots in coupled photonic crystal cavities without using classical laser pulses
Laser Physics Letters, 2014Co-Authors: Xinxin Jiang, Wenxue Cui, Hong-fu WangAbstract:We propose a scheme to implement a three-Qubit controlled phase gate with one control Qubit and two Target Qubits using quantum dots (QDs) in two coupled photonic crystal (PC) cavities A and B. In the scheme, three QDs are embedded in two coupled photonic crystal cavities and the transitions between the levels are only coupled to the cavity modes without being driven by the classical laser fields. We investigate the dynamics of the system consisting of resonant and off-resonant couplings between the cavity modes and QDs and solve the time-dependent Schrodinger equation analytically. The results show that a three-Qubit controlled phase gate can be directly implemented using one operational step, by exchanging a single photon between the PC cavities A and B. This scheme greatly simplifies the gate operation in experiments.
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one step implementation of a multiQubit phase gate with one control Qubit and multiple Target Qubits in coupled cavities
Optics Letters, 2014Co-Authors: Hong-fu Wang, Aidong Zhu, Shou ZhangAbstract:We propose a one-step scheme to implement a multiQubit controlled phase gate with one Qubit simultaneously controlling multiple Qubits with three-level atoms at distant nodes in coupled cavity arrays. Selective Qubit–Qubit couplings are achieved by adiabatically eliminating the atomic excited states and photonic states, and the required phase shifts between the control Qubit and any Target Qubit can be realized through suitable choices of the parameters of the external fields. Moreover, the effective model is robust against decoherence because neither the atoms nor the field modes are excited during the gate operation, leading to a useful step toward scalable quantum computing networks.
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one step implementation of multiQubit phase gate with one control Qubit and multiple Target Qubits in coupled cavities
arXiv: Quantum Physics, 2014Co-Authors: Hong-fu Wang, Aidong Zhu, Shou ZhangAbstract:We propose a one-step scheme to implement a multiQubit controlled phase gate of one Qubit simultaneously controlling multiple Qubits with three-level atoms at distant nodes in coupled cavity arrays. The selective Qubit-Qubit couplings are achieved by adiabatically eliminating the atomic excited states and photonic states and the required phase shifts between the control Qubit and any Target Qubit can be realized through suitable choices of the parameters of the external fields. Moreover, the effective model is robust against decoherence because neither the atoms nor the field modes during the gate operation are excited, leading to a useful step toward scalable quantum computing networks.
Shi-biao Zheng - One of the best experts on this subject based on the ideXlab platform.
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single step implementation of a multiple Target Qubit controlled phase gate without need of classical pulses
Optics Letters, 2014Co-Authors: Chui-ping Yang, Fengyang Zhang, Shi-biao ZhengAbstract:We propose a simple method for achieving a multiQubit phase gate of one Qubit simultaneously controlling n Target Qubits, by using three-level quantum systems (i.e., qutrits) coupled to a cavity or resonator. The gate can be realized via one operational step, without need of classical pulses, and by a virtual photon process. Thus, the gate operation is greatly simplified and decoherence from the cavity decay is much reduced, when compared with previous proposals. In addition, the operation time is independent of the number of Qubits and no adjustment of the qutrit level spacings or the cavity frequency is needed during the operation.
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single step implementation of a multiple Target Qubit controlled phase gate without need of classical pulses
arXiv: Quantum Physics, 2014Co-Authors: Chui-ping Yang, Fengyang Zhang, Shi-biao ZhengAbstract:We propose a simple method for realizing a multiQubit phase gate of one Qubit simultaneously controlling $n$ Target Qubits, by using three-level quantum systems (i.e., qutrits) coupled to a cavity or resonator. The gate can be implemented using one operational step and without need of classical pulses, and no photon is populated during the operation. Thus, the gate operation is greatly simplified and decoherence from the cavity decay is much reduced, when compared with the previous proposals. In addition, the operation time is independent of the number of Qubits and no adjustment of the qutrit level spacings or the cavity frequency is needed during the operation.
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multiQubit tunable phase gate of one Qubit simultaneously controlling n Qubits in a cavity
Physical Review A, 2010Co-Authors: Chui-ping Yang, Shi-biao Zheng, Franco NoriAbstract:We propose how to realize a multiQubit tunable phase gate of one Qubit simultaneously controlling $n$ Qubits with four-level quantum systems in a cavity or coupled to a resonator. Each of the $n$ two-Qubit controlled-phase (cp) gates involved in this multiQubit phase gate has a shared control Qubit but a different Target Qubit. In this proposal, the two lowest levels of each system represent the two logical states of a Qubit while the two higher-energy intermediate levels are used for the gate implementation. The method presented here operates essentially by creating a single photon through the control Qubit, which then induces a phase shift to the state of each Target Qubit. The phase shifts on each Target Qubit can be adjusted by changing the Rabi frequencies of the pulses applied to the Target Qubit systems. The operation time for the gate implementation is independent of the number of Qubits, and neither adjustment of the Qubit level spacings nor adjustment of the cavity mode frequency during the gate operation is required by this proposal. It is also noted that this approach can be applied to implement certain types of significant multiQubit phase gates (e.g., the multiQubit phase gate consisting of $n$ two-Qubit cp gates which are key elements in quantum Fourier transforms). A possible physical implementation of our approach is presented. Our proposal is quite general and can be applied to physical systems such as various types of superconducting devices coupled to a resonator and trapped atoms in a cavity.
Weining Zhang - One of the best experts on this subject based on the ideXlab platform.
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one step implementation of a multi Target Qubit controlled phase gate in a multi resonator circuit qed system
Quantum Information Processing, 2018Co-Authors: Tong Liu, Baoqing Guo, Yang Zhang, Weining ZhangAbstract:Circuit quantum electrodynamics system composed of many Qubits and resonators may provide an excellent way to realize large-scale quantum information processing (QIP). Because of key role for large-scale QIP and quantum computation, multi-Qubit gates have drawn intensive attention recently. Here, we present a one-step method to achieve a multi-Target-Qubit controlled phase gate in a multi-resonator system, which possesses a common control Qubit and multiple different Target Qubits distributed in their respective resonators. Noteworthily, the implementation of this multi-Qubit phase gate does not require classical pulses, and the gate operation time is independent of the number of Qubits. Besides, the proposed scheme can in principle be adapted to a general type of Qubits like natural atoms, quantum dots, and solid-state Qubits (e.g., superconducting Qubits and NV centers).
