Decoherence control in different environments

Abstract

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.

8 pages, 4 figures, new figures added, text modified for clarity

References in corpus (8)

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• Quantum Zeno dynamics: mathematical and physical aspects
• Non-Markovian quantum jumps
• Non-Markovian quantum dynamics: local versus non-local
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• Engineering arbitrary pure and mixed quantum states
• Bath induced coherence and the secular approximation
• Heisenberg-Langevin vs. quantum master equation
• Quantum Zeno and anti-Zeno effects on quantum and classical correlations
• Coherence and entanglement of mechanical oscillators mediated by coupling to different baths
• Finite-time quantum-to-classical transition for a Schroedinger-cat state
• Quantum to classical transition induced by gravitational time dilation
• Environment dependent vibrational heat transport in molecular Junctions : Rectification, quantum effects, vibrational mismatch
• Mesoscopic fluctuations in biharmonically driven flux qubits