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An experimental condensed matter physicist who coauthored coherent control of a superconducting electrical circuit. Microwave pulses programmed evolution between two circuit states, while a pulsed readout circuit measured the result. The device behaved as an artificial two-level system, making a fabricated circuit a controllable carrier of quantum information.^[ref]

A condensed matter physicist who coauthored the quantronium circuit experiment. The superconducting device combined microwave state manipulation with a separate pulsed measurement circuit, allowing coherent evolution and readout of an electrical qubit. It supplied an experimental connection between circuit design and the dynamics of a controllable quantum state.^[ref]

Cristian Urbina coauthored manipulation and readout of a superconducting electrical qubit. Microwave pulse sequences programmed its quantum state, while a separate pulsed subcircuit measured the outcome.^[ref]

Identity source: iramis.cea.fr/en/spec/gq/membres-gq-en/

Daniel Esteve coauthored the quantronium demonstration of coherent superconducting-circuit control. Its combination of programmable microwave evolution and pulsed readout made an electrical circuit a candidate carrier of quantum information.^[ref]

Identity source: iramis.cea.fr/en/spec/gq/membres-gq-en/

Denis Vion coauthored the quantronium experiment: microwave pulses controlled the quantum state of a superconducting circuit behaving as a two-level system, with separate pulsed readout.^[ref]

Identity source: iramis.cea.fr/en/spec/gq/membres-gq-en/

Hugues Pothier coauthored the quantronium experiment, in which a superconducting tunnel-junction circuit acted as an artificial two-level system with programmable microwave-driven evolution and pulsed quantum measurement.^[ref]

Identity source: iramis.cea.fr/en/spec/gq/membres-gq-en/

Philippe Joyez coauthored coherent control of the quantronium qubit. The circuit separated microwave state manipulation from pulsed measurement, connecting superconducting-device design with controlled two-state quantum dynamics.^[ref]

Identity source: iramis.cea.fr/en/spec/gq/membres-gq-en/

The 2002 experiment described in Manipulating the Quantum State of an Electrical Circuit demonstrates Ramsey interferometry in a circuit using superconductivity. An aluminum island between two small Josephson junctions and a larger readout Josephson junction formed the loop; a dilution refrigerator cooled it. Manipulation used the charge/flux bias point least sensitive to first-order fluctuations. Microwave pulse amplitude and duration were calibrated using Rabi oscillations. Two phase-coherent $\pi /2$ pulses then enclosed a variable free interval. A current pulse switched the large Josephson junction to finite voltage with state-dependent probability; a preamplifier and threshold discriminator counted repeated trials.^[ref]

As a readout control, switching was tested against pulse height at thermal equilibrium. The Ramsey interferometry oscillation period agreed with inverse frequency detuning, supporting relative quantum phase accumulation against the external oscillator. The decaying envelope indicated finite quantum coherence, while reduced contrast was attributed provisionally to population relaxation during readout. This supports controlled coherent evolution over a finite interval, without establishing perfect isolation or identifying one exclusive noise mechanism.^[ref]