Hole spin qubit in silicon: enhanced coherence and coherent coupling to microwave photons

Semiconductor spin qubits based on spin-orbit states stand as promising candidates for quantum information processing. In particular, owing to the spin-orbit interaction (SOI) of valence band states, hole spins are responsive to electric field excitations, allowing for practical and fast qubit control. This spin-electric response is intimately link to the rich spin-orbit physics [1,2]. Here we will report on our last efforts leveraging spin-orbit interaction of hole spin in silicon devices produced on a semi-industrial 300mm CMOS foundry [3]. First, we will demonstrate how SOI turns into an asset to engineer mixed spin-charge states in a double quantum dot able to couple strongly with microwave photons. In an hybrid spin cQED platform, we find a hole spin-photon coupling of 300 MHz associated to a cooperativity above 10³ [4]. Secondly, due to their spin-electric susceptibility, spin-orbit qubits may be vulnerable to electrical noise explaining the relatively short coherence time reported so far. Here we will report on the existence of preferential magnetic field orientation at which a spin-orbit qubit is decoupled from charge noise while keeping its efficient electrical control [5]. In this peculiar operation regime, we measure an enhanced Hahn-Echo decay time in the order of 100 microseconds maintaining Rabi frequencies in the MHz range [6]. All together, the coupling to microwave photon and the ability to hide from charge noise make hole spin in silicon an attractive platform to further develop semiconductor spin qubit-based quantum information processing.

[1] Golovach et al. PRB 74,1-10 (2006)

[2] Kato et al. Science 299,1201 (2003)

[3] Maurand et al. Nat. Com.7, 13575 (2016)

[4] Yu et al. arXiv :2206.14082 (2022)

[5] Bosco et al. PRL 129, 066801 (2022) & Michal et al. arXiv preprint arXiv:2204.00404

[6] Piot et al. Nat. Nano. 17, 1072 (2022)