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arXiv · 1608.04195

Heralded quantum controlled phase gates with dissipative dynamics in macroscopically-distant resonators

Wei Qin·Xin Wang·Adam Miranowicz·Zhirong Zhong·Franco Nori
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Abstract

Heralded near-deterministic multi-qubit controlled phase gates with integrated error detection have recently been proposed by Borregaard et al. [Phys. Rev. Lett. 114, 110502 (2015)]. This protocol is based on a single four-level atom (a heralding quartit) and $N$ three-level atoms (operational qutrits) coupled to a single-resonator mode acting as a cavity bus. Here we generalize this method for two distant resonators without the cavity bus between the heralding and operational atoms. Specifically, we analyze the two-qubit controlled-Z gate and its multi-qubit-controlled generalization (i.e., a Toffoli-like gate) acting on the two-lowest levels of $N$ qutrits inside one resonator, with their successful actions being heralded by an auxiliary microwave-driven quartit inside the other resonator. Moreover, we propose a circuit-quantum-electrodynamics realization of the protocol with flux and phase qudits in linearly-coupled transmission-line resonators with dissipation. These methods offer a quadratic fidelity improvement compared to cavity-assisted deterministic gates.

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Wei Qin, Xin Wang, Adam Miranowicz, Zhirong Zhong, Franco Nori. 2017-07-12. Heralded quantum controlled phase gates with dissipative dynamics in macroscopically-distant resonators. https://doi.org/10.1103/physreva.96.012315

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