### Abstract

When one of the parameters in the Euler-Lagrange
equations of motion of a sys- tem is modulated, particles
can be generated out of the quantum vacuum. This
phenomenon is known as the dynamical Casimir effect, and
it was recently realized experimentally in systems of
superconducting circuits, for example by using modulated
resonators made of coplanar waveg- uides, or arrays of
superconducting quantum intereference devices (SQUIDs)
forming a Josephson metamaterial. In this paper, we
consider a simple electrical circuit model for dynamical
Casimir effects, consisting of an LC resonator, with the
inductor modulated externally at 10.8 GHz and with the
resonant frequency tunable over a range of ±400MHz around
5.4 GHz. The circuit is analyzed classically using a
circuit simulator (APLAC). We demonstrate that if an
additional source of classical noise couples to the
resonator (on top of the quantum vacuum), for example via
dissipative "internal modes", then the resulting spectrum
of the photons in the cavity will present two strongly
asymmetric branches. However, according to the theory of
the dynamical Casimir effect, these branches should be
symmetric, a prediction which is confirmed by our ex-
perimental data. The simulation presented here therefore
shows that the origin of the photons generated in our
experiment with Josephson metamaterials is the quantum
vacuum, and not a spurious classical noise source.

Original language | English |
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Title of host publication | Proceedings |

Subtitle of host publication | Progress in Electromagnetics Research Symposium, PIERS 2013 |

Publisher | Electromagnetics Academy |

Pages | 151-153 |

ISBN (Print) | 978-193414224-0 |

Publication status | Published - 2013 |

MoE publication type | Not Eligible |

Event | 33rd Progress in Electromagnetics Research Symposium, PIERS 2013 - Taipei, Taiwan, Province of China Duration: 25 Mar 2013 → 28 Mar 2013 Conference number: 33 |

### Conference

Conference | 33rd Progress in Electromagnetics Research Symposium, PIERS 2013 |
---|---|

Abbreviated title | PIERS 2013 |

Country | Taiwan, Province of China |

City | Taipei |

Period | 25/03/13 → 28/03/13 |

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## Cite this

Lähteenmäki, P., Paraoanu, G. S., Hassel, J., & Hakonen, P. (2013). Photon generation from quantum vacuum using a josephson metamaterial. In

*Proceedings: Progress in Electromagnetics Research Symposium, PIERS 2013*(pp. 151-153). Electromagnetics Academy.