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The reversible transfer of unknown quantum states between light and matter is essential for constructing large-scale quantum networks. Over the last decade, various physical systems have been proposed to realize such quantum memory for light. The solid-state quantum memory based on rare-earth-ion-doped solids has the advantages of a reduced setup complexity and high robustness for scalable application. We describe the methods used to spectrally prepare the quantum memory and release the photonic excitation on-demand. We will review the state of the art experiments and discuss the perspective applications of this particular system in both quantum information science and fundamental tests of quantum physics. [ABSTRACT FROM AUTHOR]

The concept of supersymmetry developed in particle physics has been applied to various fields of modern physics. In quantum mechanics, the supersymmetric systems refer to the systems involving two supersymmetric partner Hamiltonians, whose energy levels are degeneracy except one of the systems has an extra ground state possibly, and the eigenstates of the partner systems can be mapped onto each other. Recently, an interferometric scheme has been proposed to show this relationship in ultracold atoms [Phys. Rev. A96 043624 (2017)]. Here this approach is generalized to linear optics for observing the supersymmetric dynamics with photons. The time evolution operator is simulated approximately via Suzuki–Trotter expansion with considering the realization of the kinetic and potential terms separately. The former is realized through the diffraction nature of light and the later is implemented using a phase plate. Additionally, we propose an interferometric approach which can be implemented perfectly using an amplitude alternator to realize the non-unitary operator. The numerical results show that our scheme is universal and can be realized with current technologies. [ABSTRACT FROM AUTHOR]

Preserving non-Markovianity and quantum entanglement from decoherence effect is of theoretical and practical significance in the quantum information processing technologies. In this context, we study a system S that is initially correlated with an ancilla A, which interacts with the environment E via an amplitude damping channel. We also consider dipole-dipole interactions (DDIs) between the system and ancilla, which are responsible for strong correlations. We investigate the impact of DDIs and detuning on the non-Markovianity and information exchange in different environments. We show that DDIs are not only better than detuning at protecting the information (without destroying the memory effect) but also induce memory by causing a transition from Markovian to non-Markovian dynamics. In contrast, although detuning also protects the information, it causes a transition from non-Markovian to the Markovian dynamics. In addition, we demonstrate that the non-Markovianity grows with increasing DDI strength and diminishes with increasing detuning. We also show that the effects of negative detuning and DDIs can cancel out each other, causing a certain loss of coherence and information. [ABSTRACT FROM AUTHOR]