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Quantum control

Squinting at quantum systems

Quantum measurements always have a back-action: they 'kick' the system in a particular way. This can be used to drive the system to any desired state using a fixed type of measurement, provided it can be 'unsharpened'.

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Figure 1: Sharp and unsharp measurements.


  1. Ashhab, S. & Nori, F. Phys. Rev. A 82, 062103 (2010).

    Article  ADS  Google Scholar 

  2. Pechen, A., Il'in, N., Shuang, F. & Rabitz, H. Phys. Rev. A 74, 052102 (2006).

    Article  ADS  Google Scholar 

  3. Jacobs, K. New J. Phys. 12, 043005 (2010).

    Article  ADS  Google Scholar 

  4. Wiseman, H. M. & Milburn, G. J. Quantum Measurement and Control (Cambridge Univ. Press, 2010).

    MATH  Google Scholar 

  5. Banaszek, K. Phys. Rev. Lett. 86, 1366–1369 (2001).

    Article  ADS  CAS  Google Scholar 

  6. Renes, J. M., Blume-Kohout, R., Scott, A. J. & Caves, C. M. J. Math. Phys. 45, 2171–2180 (2004).

    Article  ADS  MathSciNet  Google Scholar 

  7. Wiseman, H. M. & Thomsen, L. K. Phys. Rev. Lett. 86, 1143–1147 (2001).

    Article  ADS  CAS  Google Scholar 

  8. Gillett, G. et al. Phys. Rev. Lett. 104, 080503 (2010).

    Article  ADS  CAS  Google Scholar 

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Correspondence to Howard M. Wiseman.

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Wiseman, H. Squinting at quantum systems. Nature 470, 178–179 (2011).

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