Rare-earth solid-state qubits

Sylvain Bertaina (1) , Serge Gambarelli (2) , Alexandra Tkachuk (3) , Igor Kurkin (4) , Boris Malkin (4) , Anatole Stepanov (5) , Bernard Barbara (6)

1 ENSPG - Ecole Nationale Polytechnique
2 SCIB - UMR E3 - Service de Chimie Inorganique et Biologique
3 S.I. Vavilov State Optical Institute
4 KPFU - Kazan State University
5 L2MP - Laboratoire matériaux et microélectronique de Provence
6 NEEL - QuantECA - Circuits électroniques quantiques Alpes

Quantum bits (qubits) are the basic building blocks of any quantum computer. Superconducting qubits have been created with a 'top-down' approach that integrates superconducting devices into macroscopic electrical circuits [1-3], whereas electron-spin qubits have been demonstrated in quantum dots [4-6]. The phase coherence time (Tau2) and the single qubit figure of merit (QM) of superconducting and electron-spin qubits are similar --- Tau2 ~ microseconds and QM ~10-1000 below 100mK --- and it should be possible to scale-up these systems, which is essential for the development of any useful quantum computer. Bottom-up approaches based on dilute ensembles of spins have achieved much larger values of tau2 (up to tens of ms) [7, 8], but these systems cannot be scaled up, although some proposals for qubits based on 2D nanostructures should be scalable [9-11]. Here we report that a new family of spin qubits based on rare-earth ions demonstrates values of Tau2 (~ 50microseconds) and QM (~1400) at 2.5 K, which suggests that rare-earth qubits may, in principle, be suitable for scalable quantum information processing at 4He temperatures.

Mots clés: quantum coherence; magnetism; spins; qubits; rare-earths

Domaines: Autre [cond-mat.other]

Sylvain Bertaina, Serge Gambarelli, Alexandra Tkachuk, Igor Kurkin, Boris Malkin, et al.. Rare-earth solid-state qubits. Nature Nanotechnology, 2007, 2, pp.39-42. ⟨10.1038/nnano.2006.174⟩. ⟨hal-00136435⟩