Download Pogosov_Abstract - Superconducting hybrid nanostructures

MIPT Conference 2016 “Superconducting hybrid nanostructures: physics and application”
Nonadiabatic QED effects with Josephson qubits
W. V. Pogosov1,2,3, A. A. Zhukov1,4, D. S. Shapiro1,2,5, S. V. Remizov1,5, and Yu. E.
Lozovik1,6
1
All-Russia Research Institute of Automatics, Moscow, Russia
Moscow Institute of Physics and Technology, Dolgoprudny, Russia
3
Institute for Theoretical and Applied Electrodynamics RAS, Moscow, Russia
4
National Research Nuclear University (MEPhI), Moscow, Russia
5
V. A. Kotel'nikov Institute of Radio Engineering and Electronics RAS, Moscow, Russia
6
Institute of Spectroscopy RAS, Troitsk, Russia
2
Quantum electrodynamics (QED) of superconducting circuits is one of fast and
intensively developing fields of a modern physics. The interest to
superconducting circuits, which consist of Josephson qubits and transmission
line cavities, is heated by the possibility of implementation of quantum
computation, observation of new phenomena of quantum optics, as well as an
engineering of sub-wavelength quantum metamaterials. An outstanding feature of
Josephson qubits is that their parameters are tunable in situ. Moreover, it is also
possible to tune certain degrees of freedom which are normally frozen in optical
systems, such as the coupling energy between the Josephson qubit and the
photon mode. This possibility makes it perspective to use superconducting
quantum circuits for investigation of various nonstationary QED effects related to
vacuum amplification and parametric generation of excitations from vacuum via
counter-rotating wave processes which are usually neglected. One of such
phenomena is the dynamical Lamb effect, induced by a nonadiabatic modulation
of atomic level Lamb shift [1], which was initially predicted for a natural atom
placed into a cavity with time-dependent parameters. We here study the
dynamical Lamb effect and accompanying quantum phenomena for the case of a
coupled superconducting qubit-resonator system under variation of either the
coupling energy [2,3] or resonator frequency [4]. Energy dissipation is taken into
account. We reveal various dynamical regimes in which dynamical Lamb effect
can be suppressed or enhanced in comparison with other channels of a
parametric qubit excitation. We also find that the effect of energy dissipation on
the dynamics of such systems can be highly nontrivial. One of the most striking
results is that photon generation from vacuum can be strongly enhanced due to
the qubit relaxation, which opens a new channel for such a process. We also
show that parametric processes can be used to efficiently create entangled
states of Josephson qubits.
[1] N. B. Narozhny, A. M. Fedotov, Yu. E. Lozovik, Phys. Rev. A 64, 053807 (2001).
[2] D. S. Shapiro, A. A. Zhukov, W. V. Pogosov, Yu. E. Lozovik, Phys. Rev. A 91, 063814 (2015).
[3] A. A. Zhukov, D. S. Shapiro, W. V. Pogosov, Yu. E. Lozovik, Phys. Rev. A 93, 063845 (2016).
[4] A. A. Zhukov, D. S. Shapiro, S. V. Remizov, W. V. Pogosov, Yu. E. Lozovik, arXiv:1607.03054.
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