214 research outputs found

    Analysis and minimization of bending losses in discrete quantum networks

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    We study theoretically the transfer of quantum information along bends in two-dimensional discrete lattices. Our analysis shows that the fidelity of the transfer decreases considerably, as a result of interactions in the neighbourhood of the bend. It is also demonstrated that such losses can be controlled efficiently by the inclusion of a defect. The present results are of relevance to various physical implementations of quantum networks, where geometric imperfections with finite spatial extent may arise as a result of bending, residual stress, etc

    Photonic simulation of entanglement growth and engineering after a spin chain quench

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    The time evolution of quantum many-body systems is one of the most important processes for benchmarking quantum simulators. The most curious feature of such dynamics is the growth of quantum entanglement to an amount proportional to the system size (volume law) even when interactions are local. This phenomenon has great ramifications for fundamental aspects, while its optimisation clearly has an impact on technology (e.g., for on-chip quantum networking). Here we use an integrated photonic chip with a circuit-based approach to simulate the dynamics of a spin chain and maximise the entanglement generation. The resulting entanglement is certified by constructing a second chip, which measures the entanglement between multiple distant pairs of simulated spins, as well as the block entanglement entropy. This is the first photonic simulation and optimisation of the extensive growth of entanglement in a spin chain, and opens up the use of photonic circuits for optimising quantum devices

    Non-classical light state transfer in su(2)su(2) resonator networks

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    We use a normal mode approach to show full and partial state transfer in a class of coupled resonator networks with underlying su(2)su(2) symmetry that includes the so-called JxJ_{x} photonic lattice. Our approach defines an auxiliary Hermitian coupling matrix describing the network that yields the normal modes of the system and its time evolution in terms of orthogonal polynomials. These results provide insight on the full quantum state reconstruction time in a general su(2)su(2) network of any size and the full quantum transfer time in the JxJ_{x} network of size 4n+14 n + 1 with n=1,2,3,…n=1,2,3,\ldots In the latter, our approach shows that the Fock state probability distribution of the initial state is conserved but the amplitudes suffer a phase shift proportional to π/2\pi/2 that results in partial quantum state transfer for any other network size.Comment: 13 pages, 1 figur
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