Parity-check building blocks are useful in quantum algorithms, quantum communications, and quantum computing, and such devices may be helpful in implementing robust universal quantum gates. We propose a scheme to construct a robust deterministic controlled-not gate on static electron-spin qubits with parity-check building blocks, assisted by double-sided-cavity quantum systems. Our device is robust against the polarization-flip errors, and it can work in both the weak coupling and strong coupling regimes, but high fidelity is achieved only when the ratio of the side leakage to the cavity loss is low. Our gate is heralded by the polarization of the single-photon medium. Finally, we assess the feasibility of this device and show it can be implemented with current technology.Parity-check building blocks are useful in quantum algorithms, quantum communications, and quantum computing, and such devices may be helpful in implementing robust universal quantum gates. We propose a scheme to construct a robust deterministic controlled-not gate on static electron-spin qubits with parity-check building blocks, assisted by double-sided-cavity quantum systems. Our device is robust against the polarization-flip errors, and it can work in both the weak coupling and strong coupling regimes, but high fidelity is achieved only when the ratio of the side leakage to the cavity loss is low. Our gate is heralded by the polarization of the single-photon medium. Finally, we assess the feasibility of this device and show it can be implemented with current technology.

Journal of the Optical Society of America BMar 30, 20165 citations

Entangling and cloning machine with increasing robustness against decoherence as the number of qubits increases

Shi‐Biao Zheng, Guang‐Can Guo

We propose a machine for entangling multiple qubits and implementing cloning and anti-cloning. The operation speed increases with the number of qubits without a limitation and thus the operation becomes more and more robust against decoherence with the increase of the number of qubits. This is contrary to usual entangling machines and quantum information processors whose performance would deteriorate with the increase of the number of qubits due to decoherence. We illustrate the idea in the ion trap system, however it can also be realized in other systems, opening a new perspective for building a scalable machine for entanglement generation and quantum information processing.We propose a machine for entangling multiple qubits and implementing cloning and anti-cloning. The operation speed increases with the number of qubits without a limitation and thus the operation becomes more and more robust against decoherence with the increase of the number of qubits. This is contrary to usual entangling machines and quantum information processors whose performance would deteriorate with the increase of the number of qubits due to decoherence. We illustrate the idea in the ion trap system, however it can also be realized in other systems, opening a new perspective for building a scalable machine for entanglement generation and quantum information processing.

Physical Review ADec 9, 200517 citations

Building a Qubit

Marcus Stephen Edwards

Springer eBooksJan 1, 20260 citations

Manipulating qubits

Michel Le Bellac

Cambridge University Press eBooksJun 15, 20061 citation

Set of holonomic and protected gates on topological qubits for a realistic quantum computer

Andrey R. Klots, L. B. Ioffe

In recent years qubit designs such as transmons have approached fidelities of up to 0.999. However, even these devices are still insufficient for realizing quantum error correction requiring better than 0.9999 fidelity. Topologically protected superconducting qubits are arguably the most prospective for building a realistic quantum computer as they are intrinsically protected from noise and leakage errors that occur in transmons. We propose a topologically protected qubit design based on a $\ensuremath{\pi}$-periodic Josephson element and a universal set of gates: A protected Clifford group and highly robust (with infidelity $\ensuremath{\lesssim}{10}^{\ensuremath{-}4}$) nondiscrete holonomic phase gate. The qubit is controlled via charge $Q$ and flux $\mathrm{\ensuremath{\Phi}}$ biases. The holonomic gate is realized by quickly, but adiabatically, going along a particular closed path in the two-dimensional ${\mathrm{\ensuremath{\Phi}},Q}$ space---a path where computational states are always degenerate but Berry curvature is localized inside the path. This gate is robust against currently achievable noise levels. This qubit architecture allows building a realistic scalable superconducting quantum computer with leakage and noise-induced errors below ${10}^{\ensuremath{-}4}$, which allows performing realistic error correction codes with currently available fabrication techniques.In recent years qubit designs such as transmons have approached fidelities of up to 0.999. However, even these devices are still insufficient for realizing quantum error correction requiring better than 0.9999 fidelity. Topologically protected superconducting qubits are arguably the most prospective for building a realistic quantum computer as they are intrinsically protected from noise and leakage errors that occur in transmons. We propose a topologically protected qubit design based on a $\ensuremath{\pi}$-periodic Josephson element and a universal set of gates: A protected Clifford group and highly robust (with infidelity $\ensuremath{\lesssim}{10}^{\ensuremath{-}4}$) nondiscrete holonomic phase gate. The qubit is controlled via charge $Q$ and flux $\mathrm{\ensuremath{\Phi}}$ biases. The holonomic gate is realized by quickly, but adiabatically, going along a particular closed path in the two-dimensional ${\mathrm{\ensuremath{\Phi}},Q}$ space---a path where computational states are always degenerate but Berry curvature is localized inside the path. This gate is robust against currently achievable noise levels. This qubit architecture allows building a realistic scalable superconducting quantum computer with leakage and noise-induced errors below ${10}^{\ensuremath{-}4}$, which allows performing realistic error correction codes with currently available fabrication techniques.

arXiv:1907.04379Physical review. B./Physical review. BOct 6, 202114 citations

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and flux $\mathrm{\ensuremath{\Phi}}$ biases. The holonomic gate is realized by quickly, but adiabatically, going along a particular closed path in the two-dimensional ${\mathrm{\ensuremath{\Phi}},Q}$ space---a path where computational states are always degenerate but Berry curvature is localized inside the path. This gate is robust against currently achievable noise levels. This qubit architecture allows building a realistic scalable superconducting quantum computer with leakage and noise-induced errors below ${10}^{\ensuremath{-}4}$, which allows performing realistic error correction codes with currently available fabrication techniques.