Optimal noninvasive measurement of full counting statistics by a single qubit

Article

关键词: REAL-TIME DETECTION;    CHARGE-TRANSPORT;    SHOT-NOISE;    QUANTUM;    COHERENT;   

DOI  :  10.1103/PhysRevB.93.115140

来源: SCIE

【 摘 要 】

The complete characterization of the charge transport in a mesoscopic device is provided by the full counting statistics (FCS) P-t(m), describing the amount of charge Q = me transmitted during the time t. Although numerous systems have been theoretically characterized by their FCS, the experimental measurement of the distribution function Pt (m) or its moments < Q(n)> is rare and often plagued by strong back-action. Here, we present a strategy for the measurement of the FCS, more specifically its characteristic function chi(lambda) and moments < Q(n)>, by a qubit with a set of different couplings lambda(j), j = 1,..., k,... k + p, k = inverted right perpendicularn/2inverted left perpendicular, p >= 0, to the mesoscopic conductor. The scheme involves multiple readings of Ramsey sequences at the different coupling strengths lambda(j), and we find the optimal distribution for these couplings lambda(j) as well as the optimal distribution N-j of N = Sigma N-j measurements among the different couplings lambda(j). We determine the precision scaling for the moments < Qn > with the number N of invested resources and show that the standard quantum limit can be approached when many additional couplings p >> 1 are included in the measurement scheme.

【 授权许可】

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