Effect of broadband noise on adiabatic passage in superconducting nanocircuits
- Autori: La Cognata, A; Caldara, P; Valenti, D; Spagnolo, B; D'Arrigo, A; Paladino, E; Falci, G
- Anno di pubblicazione: 2010
- Tipologia: Altro
- Parole Chiave: STIRAP; Quantronium; Coherent transfer population; Zener transition; Three-level system.
- OA Link: http://hdl.handle.net/10447/50304
With the rapid technological progress in quantum-state engineering in superconducting devices there is an increasing demand for techniques of quantum control. Stimulated Raman adiabatic passage (STIRAP) is a powerful method in quantum optics which has remained largely unknown to solid-state physicists. It is used to achieve highly efficient and controlled population transfer in (discrete) multilevel quantum systems. Apart from other potential applications in solid-state physics, adiabatic passage offers interesting possibilities to manipulate qubit circuits, in particular for the generation of nonclassical states in nanomechanical or electromagnetic resonators. In this contribution, we study in detail a possible implementation of the STIRAP protocol in the Quantronium, a superconducting nanocircuit based on Josephson junctions in the so called charge-phase regime. Il has been proposed that this devices is a good candidate for observing coherent adiabatic population transfer for its characteristics of low decoherence and efficient addressability by external AC electromagnetic fields. In particular we present a detailed analysis of the efect of broadband charge noise, which is the main source of decoherence for this device, extending to a three level system the theory proposed in Ref.. It is shown that the effect of high-frequency noise is similar to the quantum optical case. The main problem in solid state devices comes from low-frequency noise, which has the 1/f form. In this case it may produce stray two-photon detunings which prevent the device to evolve adiabaticaly towards the correct target state. However inducing Zener tunneling between Autler-Townes states it is shown to increase the population transfer efficiency, minimizing the effect of low-frequency noise.