2003/05/31 by T. Duty, D. Gunnarsson, David Gunnarsson +3 · 4 citations
Computer Science · Physics and Astronomy · #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum and electron transport phenomena #cond-mat.mes-hall #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.69.140503
published as Phys. Rev. B 69, 140503 (2004) · accepted for publication in Phys. Rev. B
arxiv created 2004/02/26 · openalex publication_date 2004/04/05 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We have fabricated a Josephson charge qubit by capacitively coupling a single-Cooper-pair box (SCB) to an electrometer based upon a single-electron transistor (SET) configured for radio-frequency readout (rf-SET). Charge quantization of 2e is observed and microwave spectroscopy is used to extract the Josephson and charging energies of the box. We perform coherent manipulation of the SCB by using very fast dc pulses and observe quantum oscillations in time of the charge that persist to \ensuremath≃10ns. The observed contrast of the oscillations is high and agrees with that expected from the finite EJ/EC ratio and finite rise time of the dc pulses. In addition, we are able to demonstrate nearly 100% initial charge state polarization. We also present a method to determine the relaxation time T1 when it is shorter than the measurement time Tmeas.