Abstract
Quantum-to-classical transition still eludes a full understanding. Out of its multiple aspects, one has recently gained an increased attention—the appearance of objective world out of the quantum. One particular idea is that objectivity appears thanks to specific quantum state structures formation during the evolution, known as spectrum broadcast structures (SBS). Despite that quite some research was already performed on this strong and fundamental form of objectivity, the practical realization of SBS in a concrete physical medium has not been explicitly analyzed so far. In this work, we study the possibility to simulate objectivization process via SBS formation using widely studied nitrogen-vacancy centers in diamonds. Assuming achievable limits of dynamical polarization technique, we show that for high, but experimentally viable polarizations (p > 0.5) of nuclear spins and for magnetic fields lower than ≈20 G the state of the NV center and its nearest polarized environment approaches an SBS state reasonably well.
Highlights
The central spin model - of a two-level system interacting with many other spins - is a paradigmatic model of decoherence [1, 2], but it has been highly relevant for description of dephasing of many kinds of semiconductor-based electron spin qubits interacting with nuclear spins [3,4,5,6,7]
Analytical studies of the decoherence and the fidelity factors, derived in the previous Section, are quite limited due to the fact that compact approximate expressions can only be obtained for weakly coupled (ω Azk, A⊥k ) or weakly polarized nuclei - and below we will show that having large polarization and strong coupling is needed for appearance of genuine Spectrum Broadcast Structures (SBS)
We have analyzed a realistic model of NV center as a ’simulator’ for an important process of the quantum-toclassical transition – the appearance of objectivity. The latter is described by Spectrum Broadcast Structures – specific multipartite quantum states, encoding an operational notion of objectivity and related to the idea of quantum Darwinism
Summary
The central spin model - of a two-level system interacting with many other spins - is a paradigmatic model of decoherence [1, 2], but it has been highly relevant for description of dephasing of many kinds of semiconductor-based electron spin qubits interacting with nuclear spins [3,4,5,6,7]. Dynamics of nuclear-induced decoherence has been understood to a very large degree for many kinds of spin qubits interacting with nuclear environments consisting of between ∼ 102 to ∼ 106 nuclei [5, 7, 8]. The spin qubit based in this center has been extensively studied theoretically and experimentally in order to characterize its spin environment (both natural, consisting of spins of 13C isotope [11,12,13], and artificially modified by putting organic molecules on top of the diamond [14, 15]) by analyzing the timedependence of dephasing of an appropriately driven qubit [16]. Having a well-tested theoretical model of open system dynamics for NV centers interacting with their nuclear environment [8, 17], one can shift the focus from the process of qubit’s loss of coherence, to the possibly accompanying processes of modification of environmental state due to interaction with the qubit
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