Berlin 2014 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 56: Quantum effects: QED II
Q 56.2: Talk
Friday, March 21, 2014, 10:45–11:00, DO26 208
Inducing coherent oscillations between a superconducting resonator and an ensemble of NV spins II. Theory — •Dmitry Krimer1, Stefan Putz2, Abhilash Valookaran2, Robert Amsüss2, Johannes Majer2, and Stefan Rotter1 — 1Institute for Theoretical Physics, Vienna University of Technology, Vienna, Austria — 2Atominstitut, Vienna University of Technology, Vienna, Austria
We study the dynamics of an ensemble of negatively charged NV centers in diamond with a strong magnetic coupling to a superconducting coplanar single-mode waveguide resonator. To accurately describe the experiment we set up a Volterra integral equation for the cavity amplitude, taking into account that the spin ensemble consists of many spins with individual frequencies, inhomogeneously distributed around a certain mean frequency. When shifting this mean frequency into resonance with the cavity mode, Rabi oscillations are found between the spin ensemble and the cavity mode which we describe accurately, including their damping which is mainly due to the non-negligible inhomogeneity of the spin distribution. Our theory predicts that this rapid decoherence process can be overcome by pumping the system by a sequence of rectangular pulses with a carrier frequency equal to the cavity mode frequency and with pulse durations matching a special resonance condition. This approach implemented successfully in the experiment, allows us not only to sustain the coherent oscillations, but even to enhance them substantially. Furthermore, our theoretical analysis discloses a crossover between Markovian and non-Markovian dynamics which is realized by varying the collective coupling strength.