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arXiv 1003.3737quant-ph
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不同环境下的退相干控制

Decoherence control in different environments

Janika Paavola, Sabrina Maniscalco

摘要:

我们研究了两种控制退相干的技术,重点是环境光谱所起的关键作用。我们展示了具有不同光谱的环境如何导致非常不同的动力学行为。我们的研究清楚地证明,这种差异必须考虑到设计退相干控制方案时。我们考虑的两种技术是油藏工程和量子芝诺控制。我们研究了一个初始制备在非经典态的量子谐振子,并在不同的玻色子热环境下解析地推导了它的非马尔可夫动力学。一方面,我们展示了如何通过改变环境的光谱来延长或缩短薛定谔猫态的寿命。另一方面,我们研究了非选择性能量测量对初始Fock态量子度退化的影响。在后一种情况下,我们看到Zeno(QZE)和anti-Zeno(AZE)效应之间的交叉,由Maniscalco等人[Phys. Rev. Lett. 97,130402(2006)]对光谱的细节高度敏感。特别是,对于某些类型的光谱,即使是非常小的系统频率的变化可能会导致测量引起的退相干加速,而不是它的抑制。

英文摘要:

We investigate two techniques for controlling decoherence, focusing on the crucial role played by the environmental spectrum. We show how environments with different spectra lead to very different dynamical behaviours. Our study clearly proves that such differences must be taken into account when designing decoherence control schemes. The two techniques we consider are reservoir engineering and quantum-Zeno control. We focus on a quantum harmonic oscillator initially prepared in a nonclassical state and derive analytically its non-Markovian dynamics in presence of different bosonic thermal environments. On the one hand we show how, by modifying the spectrum of the environment, it is possible to prolong or reduce the life of a Schrödinger cat state. On the other hand we study the effect of nonselective energy measurements on the degradation of quantumness of initial Fock states. In this latter case we see that the crossover between Zeno (QZE) and anti-Zeno (AZE) effects, discussed by Maniscalco et al. [Phys. Rev. Lett. 97, 130402 (2006)], is highly sensitive to the details of the spectrum. In particular, for certain types of spectra, even very small variations of the system frequency may cause a measurement-induced acceleration of decoherence rather than its inhibition.

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