Continuous quantum measurement with particular output: pure wavefunction evolution instead of decoherence

1998/08/17 by Alexander N. Korotkov, Korotkov, Alexander N.
Computer Science · Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum Physics (quant-ph) #cond-mat.mes-hall #quant-ph

paper · pdf · doi:10.48550/arxiv.quant-ph/9808026

short version of quant-ph/9807051 (4 pages, 2 figures)

arxiv created 1998/08/17 · openalex publication_date 1998/08/17 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We consider a continuous measurement of a two-level system (double-dot) by weakly coupled detector (tunnel point contact nearby). While usual treatment leads to the gradual system decoherence due to the measurement, we show that the knowledge of the measurement result can restore the pure wavefunction at any time (this can be experimentally verified). The formalism allows to write a simple Langevin equation for the random evolution of the system density matrix which is reflected and caused by the stochastic detector output. Gradual wavefunction ``collapse'' and quantum Zeno effect are naturally described by the equation.

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