论文标题
离散时间量子步行中的探测连贯性和噪声耐受性：揭示自我关注和呼吸动力学
Probing coherence and noise tolerance in discrete-time quantum walks: unveiling self-focusing and breathing dynamics
论文作者
论文摘要
量子系统对外部干扰的敏感性是实施功能量子设备，量子信息和计算的基本问题。基于光学和超冷气体的显着实验进展，我们研究了短时（瞬时）噪声的后果，而依赖强度的相时，与在$ n $ cycle上传播的量子相关。通过采用量子相干度量，我们报告了迄今未知的量子步行的新出现的状态，例如自我关注和呼吸动力学。我们的结果推出了有利于稳定制度的适当设置，渐近分布在弱非线性中幸存，并以$ 1/n $的价格消失在热力学限制中。显示不同机制阈值的图显示了量子门接近Pauli-Z是更耐噪声的。当我们朝着Pauli-X量子门移动时，这种智慧急剧下降，而对自我关注的机制的门槛几乎变得不可避免。接近Hadamard的量子门表现出一个不寻常的方面，其中非线性强度的增量可以从自我关注方向上消除动力学。
The sensitivity of quantum systems to external disturbances is a fundamental problem for the implementation of functional quantum devices, quantum information and computation. Based on remarkable experimental progress in optics and ultra-cold gases, we study the consequences of a short-time (instantaneous) noise while an intensity-dependent phase acquisition is associated with a qubit propagating on $N$-cycle. By employing quantum coherence measures, we report emerging unstable regimes in which hitherto unknown quantum walks arise, such as self-focusing and breathing dynamics. Our results unveil appropriate settings which favor the stable regime, with the asymptotic distribution surviving for weak nonlinearities and disappearing in the thermodynamic limit with $1/N$. The diagram showing the threshold between different regimes reveals the quantum gates close to Pauli-Z as more noise-tolerant. As we move towards the Pauli-X quantum gate, such aptness dramatically decreases and the threshold to self-focusing regime becomes almost unavoidable. Quantum gates close to Hadamard exhibit an unusual aspect, in which an increment of the nonlinear strength can remove the dynamics from self-focusing regime.
