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arXiv · 2008.07444

Fully Arbitrary Control of Frequency-Bin Qubits

Hsuan-Hao Lu·Emma M. Simmerman·Pavel Lougovski·Andrew M. Weiner·Joseph M. Lukens
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Abstract

Accurate control of two-level systems is a longstanding problem in quantum mechanics. One such quantum system is the frequency-bin qubit: a single photon existing in superposition of two discrete frequency modes. %and a potential building block for scalable, fiber-compatible quantum information processing. In this work, we demonstrate fully arbitrary control of frequency-bin qubits in a quantum frequency processor for the first time. We numerically establish optimal settings for multiple configurations of electro-optic phase modulators and pulse shapers, experimentally confirming near-unity mode-transformation fidelity for all fundamental rotations. Performance at the single-photon level is validated through the rotation of a single frequency-bin qubit to 41 points spread over the entire Bloch sphere, as well as tracking of the state path followed by the output of a tunable frequency beamsplitter, with Bayesian tomography confirming state fidelities $\mathcal{F}_\rho>0.98$ for all cases. Such high-fidelity transformations expand the practical potential of frequency encoding in quantum communications, offering exceptional precision and low noise in general qubit manipulation.

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Hsuan-Hao Lu, Emma M. Simmerman, Pavel Lougovski, Andrew M. Weiner, Joseph M. Lukens. 2020-08-17. Fully Arbitrary Control of Frequency-Bin Qubits. https://doi.org/10.1103/physrevlett.125.120503

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