Squeezing of a quantum flux in a double rf-SQUID system

Autor(en)

Kohji Takashima, Shigemasa Matsuo, Toshiyuki Fujii, Noriyuki Hatakenaka, Susumu Kurihara, Anton Zeilinger

Abstrakt

We investigate the nonstationary boundary effect for a quantum flux in a double rf-SQUID system. In a superconducting ring interrupted by a dc-SQUID (so-called double rf-SQUID), the Josephson potential can be controlled by the magnetic flux through the dc-SQUID ring. This system is equivalent to an anharmonic oscillator with a time-dependent frequency. A rapid change of the magnetic flux in the dc-SQUID leads to the nonadiabatic mixing of the quantum states for a quantum flux in a double rf-SQUID. Therefore, this becomes a circuit analogue of the dynamical Casimir effect in quantum field theory. We perform numerical calculations for the quantum state evolution of the quantum flux within a harmonic approximation, taking account of the nonadiabatic effect. We found that the resulting state distribution has a super-Poissonian character that reflects flux squeezing caused by the Bogoliubov transformation between eigenstates at different times.

Organisation(en)

Quantenoptik, Quantennanophysik und Quanteninformation

Externe Organisation(en)

Hiroshima University, Waseda University

Anzahl der Seiten

4

DOI

https://doi.org/10.1088/1742-6596/150/5/052260

Publikationsdatum

2009

ÖFOS 2012

103026 Quantenoptik, 103025 Quantenmechanik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/c99f860d-6d82-4dfc-be4e-b75e4133cccf