Continuous-wave nonclassical light with gigahertz squeezing bandwidth

Stefan Ast, Aiko Samblowski, Moritz Mehmet, Sebastian Steinlechner, Tobias Eberle, Roman Schnabel*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Squeezed states can be employed for entanglement-based continuous-variable quantum key distribution, where the secure key rate is proportional to the bandwidth of the squeezing. We produced a nonclassical cw laser field at the telecommunication wavelength of 1550 nm, which showed squeezing over a bandwidth of more than 2 GHz. The experimental setup used parametric downconversion via a periodically poled potassium titanyl phosphate crystal. We did not use any resonant enhancement for the fundamental wavelength, which should in principle allow a production of squeezed light over the full phase-matching bandwidth of several nanometers. We measured the squeezing to be up to 0.3 dB below the vacuum noise from 50 MHz to 2 GHz limited by the measuring bandwidth of the homodyne detector. The squeezing strength was possibly limited by thermal lensing inside the nonlinear crystal. (C) 2012 Optical Society of America

Original languageEnglish
Pages (from-to)2367-2369
Number of pages3
JournalOptics Letters
Issue number12
Publication statusPublished - 15 Jun 2012
Externally publishedYes



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