174th RQC Seminar
講演者
Mr. Finn Schmolke
( Institute for Theoretical Physics I, University of Stuttgart, Germany )日程
2024年11月21日（木） 16:00-17:00
開催場所
ハイブリッド（ZOOM・ 和光地区 研究本館3階 セミナー室(345-347) (C01)）
講演タイトル
Quantum Synchronization and Ergodicity Breaking
お問合せ
norilab_rqc_assist[at]ml.riken.jp
講演概要
Random fluctuations can lead to cooperative behavior in classical complex systems.
For instance, coherent activation of sensory neurons may be triggered by a common noise signal leading to the effect of noise-induced synchronization.
We show that this classical phenomenon can be extended to the quantum regime.
In particular, we show that a spin chain subject to Gaussian white noise on a single site exhibits stable synchronization of the individual z-polarizations and present precise synchronization conditions for arbitrary system size.
These results are verified and extended with superconducting qubits in the first experiment on noise-induced quantum synchronization.
However, synchronization induced by classical noise emerges only on average over the ensemble of noise realizations while
'single shot' synchronization, where synchronous dynamics appears for individual realizations, would be more desirable.
In contrast, quantum noise, that may for instance be induced by continuous measurement, has a more profound impact on quantum systems.
Indeed, observing a quantum object may dramatically affect its dynamics in a non-classical manner.
In this case, we show that a continuously monitored quantum many-body system can undergo an irreversible localization transition from stochastic dynamics to noise-free stable synchronization at the level of individual quantum trajectories, when subject to standard homodyne detection.
On the trajectory level, ergodicity is thus typically broken and synchronization may appear along individual realizations while being absent at the ensemble level.
Reference:
• noise-induced sync, https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.250601
• experiment, https://arxiv.org/abs/2406.10457
• measurement-induced sync, https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.010402