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FM: Fall Meeting

FM 80: Enabling Technologies: Cavity QED

FM 80.3: Talk

Donnerstag, 26. September 2019, 14:45–15:00, 2006

Optimal Dispersive Readout of a Spin Qubit with a Microwave Cavity — •Benjamin D’Anjou and Guido Burkard — Department of Physics, University of Konstanz, D-78457 Konstanz, Germany

Strong coupling of semiconductor spin qubits to superconducting microwave cavities was recently demonstrated. These breakthroughs pave the way for quantum information processing that combines the long coherence times of solid-state spin qubits with the long-distance connectivity, fast control, and fast high-fidelity quantum-non-demolition readout of existing superconducting qubit implementations. Here, we theoretically analyze and optimize the dispersive readout of a single spin in a semiconductor double quantum dot (DQD) coupled to a microwave cavity via its electric dipole moment. The strong spin-photon coupling arises from the motion of the electron spin in a local magnetic field gradient. We calculate the signal-to-noise ratio (SNR) of the readout accounting for both Purcell spin relaxation and spin relaxation arising from intrinsic electric noise within the semiconductor. We express the maximum achievable SNR in terms of the cooperativity associated with these two dissipation processes. We then optimize the SNR as a function of experimentally tunable DQD parameters. We estimate that with current technology, single-shot readout fidelities in the range 82%-95% can be achieved within a few µs of readout time without requiring the use of Purcell filters.

arXiv reference: https://arxiv.org/abs/1905.09702