# Regensburg 2019 – wissenschaftliches Programm

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# HL: Fachverband Halbleiterphysik

## HL 10: Quantum information systems

### HL 10.2: Vortrag

### Montag, 1. April 2019, 15:15–15:30, H36

**Optimization of the Dispersive Readout of a Spin Qubit** — •Benjamin D'Anjou and Guido Burkard — Universitätstr. 10, D-78464 Konstanz, Deutschland

Recently, strong coherent coupling of semiconductor spin qubits with a superconducting microwave resonator was demonstrated in several settings [1-3]. These breakthroughs pave the way for quantum information processing platforms that combine the long coherence times characteristic of solid-state spin qubits with the long-distance connectivity, fast control, and fast high-fidelity non-demolition readout that have so far been the hallmark of superconducting qubit implementations. Here, we analyze the dispersive readout of a single spin in a double quantum dot coupled to a microwave cavity via its dipole moment. The strong spin-photon coupling arises from the admixture of electronic charge and spin induced by a strong local magnetic field gradient. We estimate the expected signal-to-noise ratio of the readout accounting for both Purcell spin relaxation and spin relaxation arising from sources of electric noise. In particular, we analyze the tradeoff between maximizing the spin-photon coupling strength and minimizing spin relaxation. We give expressions for the values of the experimentally tunable parameters that maximize the signal-to-noise ratio.

[1] Mi et al., Nature 555, p. 599 (2018)

[2] Landig et al., Nature 560, p. 179 (2018)

[3] Samkharadze et al., Science 359, p. 1123 (2018)