Ultra-long quantum walks via spin–orbit photonics

Colandrea, Francesco Di; Babazadeh, Amin; Dauphin, Alexandre; Massignan, Pietro; Marrucci, Lorenzo; Cardano, Filippo

doi:10.1364/optica.474542

Cited by 16 publications

(6 citation statements)

References 43 publications

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“…The composed functional logic network would have great potential in high-dimensional photonics, optical computing and high-capacity optical informatics. In particular, it might benefit some computation concepts in the analogous version of quantum walks 46 , 47 , since the non-separable-states-mediated coins could allow more complex form and more flexible coin rotation rules in this logic network (see more discussions in Supplementary Note 6 ).…”

Section: Resultsmentioning

confidence: 99%

Logical rotation of non-separable states via uniformly self-assembled chiral superstructures

Zhang,

Liu,

Chen

et al. 2024

Nat Commun

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The next generation of high-capacity, multi-task optical informatics requires sophisticated manipulation of multiple degrees of freedom (DoFs) of light, especially when they are coupled in a non-separable way. Vector beam, as a typical non-separable state between the spin and orbital angular momentum DoFs, mathematically akin to entangled qubits, has inspired multifarious theories and applications in both quantum and classical regimes. Although qubit rotation is a vital and ubiquitous operation in quantum informatics, its classical analogue is rarely studied. Here, we demonstrate the logical rotation of vectorial non-separable states via the uniform self-assembled chiral superstructures, with favorable controllability, high compactness and exemption from formidable alignment. Photonic band engineering of such 1D chiral photonic crystal renders the incident-angle-dependent evolution of the spatially-variant polarizations. The logical rotation angle of a non-separable state can be tuned in a wide range over 4π by this single homogeneous device, flexibly providing a set of distinguished logic gates. Potential applications, including angular motion tracking and proof-of-principle logic network, are demonstrated by specific configuration. This work brings important insight into soft matter photonics and present an elegant strategy to harness high-dimensional photonic states.

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Section: Resultsmentioning

confidence: 99%

Logical rotation of non-separable states via uniformly self-assembled chiral superstructures

Zhang,

Liu,

Chen

et al. 2024

Nat Commun

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“…Index of bases Overall, our approach provides a promising avenue for addressing the challenges associated with verifying open QW. We expect that these results will lead to new insights and discoveries in this exciting area of research on numerous physical systems such as fiber loop (74), spatial path (75), orbital angular momentum (76), transverse momentum (77,78), hybrid architecture (79), etc. Moreover, the full quantum state tomography technique can be combined with the known abilities of arbitrary initialization (14,24) and flexible manipulation, which can inspire a prospective QW platform for developing diverse applications in a range of fields.…”

Section: Discussionmentioning

confidence: 99%

Efficient learning of mixed-state tomography for photonic quantum walk

Wang,

Dong,

et al. 2024

Sci. Adv.

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Noise-enhanced applications in open quantum walk (QW) has recently seen a surge due to their ability to improve performance. However, verifying the success of open QW is challenging, as mixed-state tomography is a resource-intensive process, and implementing all required measurements is almost impossible due to various physical constraints. To address this challenge, we present a neural-network–based method for reconstructing mixed states with a high fidelity (∼97.5%) while costing only 50% of the number of measurements typically required for open discrete-time QW in one dimension. Our method uses a neural density operator that models the system and environment, followed by a generalized natural gradient descent procedure that significantly speeds up the training process. Moreover, we introduce a compact interferometric measurement device, improving the scalability of our photonic QW setup that enables experimental learning of mixed states. Our results demonstrate that highly expressive neural networks can serve as powerful alternatives to traditional state tomography.

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“…Accordingly, both in cascaded setups and looped architectures, optical losses scale exponentially with the number of steps, thus preventing the simulations of extreme dynamics spanning large-scale lattices. To overcome this limitation, we propose a novel approach that allows compressing hundreds of time steps of translation-invariant QWs within only three liquid-crystal metasurfaces (LCMSs) [5].…”

Section: Introductionmentioning

confidence: 99%

Spin-orbit photonic circuits for quantum simulations

Di Colandrea,

Babazadeh,

Dauphin

et al. 2024

Quantum Computing, Communication, and Simulation IV

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The observation of extreme dynamics within quantum simulators based on photonic circuits is typically precluded by optical losses, exponentially increasing with the system depth or, equivalently, with the number of optical components. This is a natural consequence of the standard approach to photonic simulations of quantum dynamics, where the complexity of the setup grows with the extension of the evolution in time. By focusing on simple protocols of discrete-time quantum walks, we show that it is possible to compress homogeneous evolutions within only three liquid-crystal metasurfaces, encompassing up to a few hundreds of time steps. By exploiting spin-orbit effects, these devices implement spacedependent polarization transformations that mix circularly polarized optical modes carrying quantized transverse momentum, mimicking the target quantum dynamics with high efficiency and accuracy. Being extremely versatile, our compact platform will pave the way to the simulations of extreme regimes of more exotic dynamics.

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Ultra-long quantum walks via spin–orbit photonics

Cited by 16 publications

References 43 publications

Logical rotation of non-separable states via uniformly self-assembled chiral superstructures

Logical rotation of non-separable states via uniformly self-assembled chiral superstructures

Efficient learning of mixed-state tomography for photonic quantum walk

Spin-orbit photonic circuits for quantum simulations

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