2009/10/31 by Carolyn Young, C. E. Young, Aashish A. Clerk +1
Computer Science · Engineering · Physics and Astronomy · #Advancements in Semiconductor Devices and Circuit Design #Charge (physics) #Detector #Mesoscopic physics #Noise (video) #Non-equilibrium thermodynamics #Physics #Quantum #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum electrodynamics #Quantum mechanics #Quantum noise #Quantum point contact #Quantum well #Shot noise #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevlett.104.186803
published as Phys. Rev. Lett. 104, 186803 (2010). · 4 pages, 2 figures
arxiv created 2010/05/04 · openalex publication_date 2010/05/04 · arxiv updated 2010/05/05 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study theoretically transitions of a double quantum-dot qubit caused by nonequilibrium charge fluctuations in a nearby quantum point contact (QPC) used as a detector. We show that these transitions are related to the fundamental Heisenberg backaction associated with the measurement, and use the uncertainty principle to derive a lower bound on the transition rates. We also derive simple expressions for the transition rates for the usual model of a QPC as a mesoscopic conductor, with screening treated at the RPA level. Finally, numerical results are presented which demonstrate that the charge noise and shot noise backaction mechanisms can be distinguished in QPCs having nonadiabatic potentials. The enhanced sensitivity of the charge noise to the QPC potential is explained in terms of interference contributions similar to those which cause Friedel oscillations.