2002/11/27 by A. Shnirman, Shnirman, A., D. Mozyrsky +3
Physics and Astronomy · #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #cond-mat.mes-hall
paper · pdf · doi:10.48550/arxiv.cond-mat/0211618
11 pages, 9 figures, v.4: version re-submitted to PRB, appendix about Majorana representation rewritten
arxiv created 2003/05/28 · arxiv updated 2009/11/30
We calculate the noise spectrum of the output signal of a quantum detector during continuous measurement of a two-level system (qubit). We generalize the previous results obtained for the regime of high voltages (when eV is much larger than the qubit's energy level splitting Δ) to the case of arbitrary voltages and temperatures. When V ∼ Δ the output spectrum is essentially asymmetric in frequency, i.e., the output signal is no longer classical. In the emission (negative frequency) part of the spectrum the peak due to the qubit's coherent oscillations can be 8 times higher that the background pedestal. For V < Δ and T=0 the coherent peaks do not appear at all.