Multi-qubit non-adiabatic holonomic controlled quantum gates in decoherence-free subspaces

Hu, Shi; Cui, Wen‐Xue; Guo, Qi; Wang, Hong-Fu; Zhu, Ai‐Dong; Zhang, Shou

doi:10.1007/s11128-016-1362-4

Cited by 5 publications

(2 citation statements)

References 45 publications

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“…In order to overcome decoherence, it is natural to think of implementing a multi-qubit gate by encoding a physical qubit into a logical qubit with auxiliary physical qubits. However, we note that all existing DFS-based schemes only focus on, at most, one-logical-qubit gates [37][38][39][40][41][42][43][44][45], two-logical-qubit gates [37][38][39][40][41][42][43][44][45][46][47], and three-logical-qubit Toffoli gates [47]. None of the DFS proposals for directly implementing a multi-logical-qubit gate in a DFS with the number of logical qubits greater than 3 has been reported.…”

Section: Introductionmentioning

confidence: 99%

Implementing a multi-target-qubit controlled-not gate with logical qubits outside a decoherence-free subspace and its application in creating quantum entangled states

Yang

Nori

2020

Phys. Rev. A

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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 a novel 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 multi-qubit 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 (DFS) 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; and (vi) This proposal is universal and can be applied to realize the proposed gate using natural atoms or artificial atoms (e.g., quantum dots, NV 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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Section: Introductionmentioning

confidence: 99%

Implementing a multi-target-qubit controlled-not gate with logical qubits outside a decoherence-free subspace and its application in creating quantum entangled states

Yang

Nori

2020

Phys. Rev. A

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“…Motivated by the above, in this work we focus on how to transfer multiqubit entangled states from operation qubits onto memory qubits, and how to protect the transferred multiqubit entangled states against decoherence induced due to interacting with phase-dumping environments during the storage. Note that phase dumping can be a dominating decoherence source for noise environments, which has been widely studied over the past years [31][32][33][34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Transferring multiqubit entanglement onto memory qubits in a decoherence-free subspace

Yang

2017

Quantum Inf Process

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Different from the previous works on generating entangled states, this work is focused on how to transfer the prepared entangled states onto memory qubits for protecting them against decoherence. We here consider a physical system consisting of n operation qubits and 2n memory qubits placed in a cavity or coupled to a resonator. A method is presented for transferring n-qubit Greenberger-Horne-Zeilinger (GHZ) entangled states from the operation qubits (i.e., information processing cells) onto the memory qubits (i.e., information memory elements with long decoherence time). The transferred GHZ states are encoded in a decoherence-free subspace against collective dephasing, and thus can be immune from decoherence induced by a dephasing environment. In addition, the state transfer procedure has nothing to do with the number of qubits, the operation time does not increase with the number of qubits, and no measurement is needed for the state transfer. This proposal can be applied to a wide range of hybrid qubits such as natural atoms and artificial atoms (e.g., various solid-state qubits).

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Quantum information processing in a decoherence-free subspace for the $$\hat{\sigma }_{x}$$ σ ^ x -type collective noise

Cui

Liu

Zhang

et al. 2018

Quantum Inf Process

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Multi-qubit non-adiabatic holonomic controlled quantum gates in decoherence-free subspaces

Cited by 5 publications

References 45 publications

Implementing a multi-target-qubit controlled-not gate with logical qubits outside a decoherence-free subspace and its application in creating quantum entangled states

Implementing a multi-target-qubit controlled-not gate with logical qubits outside a decoherence-free subspace and its application in creating quantum entangled states

Transferring multiqubit entanglement onto memory qubits in a decoherence-free subspace

Quantum information processing in a decoherence-free subspace for the $$\hat{\sigma }_{x}$$ σ ^ x -type collective noise

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