arXiv subjects

Tai-Yu Zheng

Publications and source records attributed to Tai-Yu Zheng.

6 recordsLinked to original sources

arXiv2018

Engineering steady Knill-Laflamme-Milburn state of Rydberg atoms by dissipation

The Knill-Laflamme-Milburn (KLM) states have been proved to be a useful resource for quantum information processing [Nature 409, 46 (2001)]. For atomic KLM states, several schemes have been put forward based on the time-dependent unitary dynamics, but the dissipative generation of these states has not been reported. This work discusses the possibility for creating different forms of bipartite KLM states in neutral atom system, where the spontaneous emission of excited Rydberg states, combined with the Rydberg antiblockade mechanism, is actively exploited to engineer a steady KLM state from an arbitrary initial state. The numerical simulation of the master equation signifies that a fidelity above 99\% is available with the current experimental parameters.

quant-ph↗

arXiv2014

Stationary three-dimensional entanglement via dissipative Rydberg pumping

We extend the recent result of bipartite Bell singlet [Carr and Saffman, Phys. Rev. Lett. {\bf111}, (2013)] to a stationary three-dimensional entanglement between two-individual neutral Rydberg atoms. This proposal makes full use of the coherent dynamics provided by Rydberg mediated interaction and the dissipative factor originating from the spontaneous emission of Rydberg state. The numerical simulation of the master equation reveals that both the target state negativity ${\cal N}(\hatρ_{\infty})$ and fidelity ${\cal F}(\hatρ_{\infty})$ can exceed 99.90%. Furthermore, a steady three-atom singlet state $|S_3\rangle$ is also achievable based on the same mechanism.

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arXiv2014

One-step implementation of the genuine Fredkin gate in high-$Q$ coupled three-cavity arrays

We present two efficient methods for implementing the Fredkin gate with atoms separately trapped in an array of three high-$Q$ coupled cavities. The first proposal is based on the resonant dynamics, which leads to a fast resonant interaction in a certain subspace while leaving others unchanged, and the second one utilizes a dispersive interaction such that the effective long-distance dipole-dipole interaction between two distributed target qubits is achieved by virtually excited process. Both schemes can achieve the standard form of the Fredkin gate in a single step without any subsequent single-qubit operation. The effects of decoherence on the performance of the gate are also analyzed in virtue of master equation, and the strictly numerical simulation reveals that the average fidelity of the quantum gate is high.

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arXiv2013

One-step achievement of robust multipartite Greenberger-Horne-Zeilinger state and controlled-phase gate via Rydberg interaction

We present a proposal for generation of a robust tripartite Greenberger-Horne-Zeilinger state among three-individual neutral Rydberg atoms. By modulating the relation between two-photon detuning and Rydberg interaction strength $U_{ij}(r)$, an effective Raman coupling is obtained between the hyperfine ground states $|F=2,M=2\rangle$ of three $^{87}$Rb atoms and the Rydberg states $|rrr\rangle$ via the third-order perturbation theory. This method is also capable of implementing a three-qubit controlled-phase gate with each qubit encoded into the hyperfine ground states $|F=1,M=1\rangle$ and $|F=2,M=2\rangle$. As an extension, we generalize our scheme to the case of multipartite GHZ state and quantum gate in virtue of high-order perturbation theory.

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arXiv2013

Dissipative creation of three-dimensional entangled state in optical cavity via spontaneous emission

We present a dissipative protocol to engineer two $^{87}Rb$ atoms into a form of three-dimensional entangled state via spontaneous emission. The combination of coupling between ground states via microwave fields and dissipation induced by spontaneous emission make the current scheme deterministic and a stationary entangled state can always be achieved without state initialization. Moreover, this scheme can be straightforwardly generalized to preparation of an $N$-dimensional entangled state in principle.

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arXiv2013

Long range universal quantum computation in large-size coupled cavity array independent of cavity number

We present a new approach for implementing a $\sqrt{\rm swap}$ gate between two spatially far apart sites connected by a large-size coupled cavity array as quantum bus. The duration is only related to the parity of cavity number but independent of a specific number of cavity, thus it is possible to process quantum information in an arbitrary long distance in principle without time varied. Referring to the recent experimental progresses on coupled-cavity array, we also make an assessment of the scalability and take the cavity number $N$ = 5 as an example to illustrate the robustness of our proposal via quantum process tomography.

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