2010/09/21 by A. Aharony, Amnon Aharony, S. A. Gurvitz +5 · 1 citation
Computer Science · Mathematics · Physics and Astronomy · #Charge qubit #Current (fluid) #Density matrix #Exponential decay #Flux qubit #Mathematics #Noise (video) #Phase qubit #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum decoherence #Quantum dot #Quantum mechanics #Quantum tunnelling #Qubit #Symmetry (geometry) #cond-mat.mes-hall #quant-ph
paper · pdf · doi:10.1103/physrevb.82.245417
published as Phys. Rev. B82, 245417 (2010) · 10 pages, 4 figures
arxiv created 2010/09/21 · openalex publication_date 2010/12/10 · arxiv updated 2013/05/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The time evolution of a qubit, consisting of two single-level quantum dots, is studied in the presence of telegraph noise. The dots are connected by two tunneling paths with an Aharonov-Bohm flux enclosed between them. Under special symmetry conditions, which can be achieved by tuning gate voltages, there develops partial decoherence: at long times, the off-diagonal element of the reduced density matrix (in the basis of the two dot states) approaches a nonzero value, generating a circulating current around the loop. The flux dependence of this current contains full information on the initial quantum state of the qubit, even at infinite time. Small deviations from this symmetry yield a very slow exponential decay toward the fully decoherent limit. However, the amplitudes of this decay also contain the full information on the initial qubit state, measurable either via the current or via the occupations of the qubit dots.