title: Coherent manipulation of Andreev states in superconducting atomic contacts.
abstract: Coherent control of quantum states has been demonstrated in a variety of superconducting devices. In all of these devices, the variables that are manipulated are collective electromagnetic degrees of freedom: charge, superconducting phase, or flux. Here we demonstrate the coherent manipulation of a quantum system based on Andreev bound states, which are microscopic quasi-particle states inherent to superconducting weak links. Using a circuit quantum electrodynamics setup, we performed single-shot readout of this Andreev qubit. We determined its excited-state lifetime and coherence time to be in the microsecond range. Quantum jumps and parity switchings were observed in continuous measurements. In addition to having possible quantum information applications, such Andreev qubits are a test-bed for the physics of single elementary excitations in superconductors.
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: C
authors.initials: C
authors.lastname: Janvier
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France. Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica, 8400 Bariloche, Argentina.
authors.forename: L
authors.initials: L
authors.lastname: Tosi
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: L
authors.initials: L
authors.lastname: Bretheau
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: Ç Ö
authors.initials: ÇÖ
authors.lastname: Girit
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: M
authors.initials: M
authors.lastname: Stern
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: P
authors.initials: P
authors.lastname: Bertet
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: P
authors.initials: P
authors.lastname: Joyez
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: D
authors.initials: D
authors.lastname: Vion
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: D
authors.initials: D
authors.lastname: Esteve
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: M F
authors.initials: MF
authors.lastname: Goffman
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: H
authors.initials: H
authors.lastname: Pothier
authors.affiliation: Quantronics Group, Service de Physique de l'État Condensé, CNRS UMR 3680, IRAMIS, CEA-Saclay, 91191 Gif-sur-Yvette, France. cristian.urbina@cea.fr.
authors.forename: C
authors.initials: C
authors.lastname: Urbina