Two-stage quantum nondemolition experiment

R. E. Slusher*, A. La Porta, S. T. Ho, B. Yurke

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution


A backaction evading (BAE) measurement apparatus based on simple optics and a parametric downconversion amplifier was previously demonstrated. An important property predicted for the BAE apparatus is that if the input state is the eigenstate of the measured quantity, the output will be in the same state as the input state. This has not been verified in any of the BAE experiments performed to date. An experiment is in progress using two BAE measurements in series. The first BAE measurement of a quadrature component of the input signal yields a readout A. As a direct result of this measurement, the transmitted signal is projected into a near eigenstate with an eigenvalue given by readout A. The larger the gain of the BAE apparatus, the more exactly this eigenstate is known. This near eigenstate, prepared by the first BAE, is then used as the input for a second BAE measurement, yielding a readout B. Correlations between readout A, readout B, and the transmitted signal demonstrate a true quantum nondemolition measurement of a known eigenstate of a quadrature component of the field.

Original languageEnglish (US)
Title of host publicationXVII International Conference on Quantum Electronics. Digest of
PublisherPubl by IEEE
Number of pages1
StatePublished - Dec 1 1990
Event17th International Conference on Quantum Electronics - IQEC '90 - Anaheim, CA, USA
Duration: May 21 1990May 25 1990


Other17th International Conference on Quantum Electronics - IQEC '90
CityAnaheim, CA, USA

ASJC Scopus subject areas

  • General Engineering


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