Sub-microsecond high-fidelity dispersive readout of a spin qubit with squeezed photons

Chon-Fai Kam; Xuedong Hu

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arXiv · 2312.10820

Sub-microsecond high-fidelity dispersive readout of a spin qubit with squeezed photons

Chon-Fai Kam·Xuedong Hu

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Abstract

Fast and high-fidelity qubit measurement is essential for realizing quantum error correction, which is in turn a key ingredient to universal quantum computing. For electron spin qubits, fast readout is one of the significant road blocks toward error correction. Here we examine the dispersive readout of a single spin in a semiconductor double quantum dot coupled to a microwave resonator. We show that using displaced squeezed vacuum states for the probing photons can improve the qubit readout fidelity and speed. Under condition of proper phase matching, we find that a moderate, and only moderate, squeezing can enhance both the signal-to-noise ratio and the fidelity of the qubit-state readout, and the optimal readout time can be shortened to the sub-microsecond range with above $99\%$ fidelity. These enhancements are achieved at low probing microwave intensity, ensuring non-demolition qubit measurement.

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Chon-Fai Kam, Xuedong Hu. 2023-12-17. Sub-microsecond high-fidelity dispersive readout of a spin qubit with squeezed photons. https://arxiv.org/abs/2312.10820

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