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1. Distributed Interference Alignment for K-user Interference Channels via Deep Learning

   https://doi.org/10.1109/ISIT45174.2021.9517735  

   Mishra, Rajesh K; Chahine, Karl; Kim, Hyeji; Jafar, Syed; Vishwanath, Sriram (July 2021, IEEE International Symposium on Information Theory (ISIT))

   null (Ed.)

   In this paper, we develop a framework for an autoencoder based transmission strategy for achieving distributed interference alignment and optimal power allocation in a multiuser interference channel. The users in the interference channel have access to the local channel state information only. We compare the explicit schemes, such as MaxSINR [1], against the autoencoder schemes. We find that the MaxSINR schemes outperform the autoencoder networks which are either jointly or distributively trained from scratch. However, we find that the autoencoders which are pretrained with the beamforming vectors and the power allocation obtained from the explicit schemes outperform the explicit schemes when the interference gets stronger. The explicit schemes perform well as they are effective in choosing the set of users which are to be suppressed. The pretrained autoencoders benefit from this initialization, and also from the fact that end to end training can improve their performance even further. We showcase our performance comparison results for 5 user interference channels with different levels of interference. 

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2. Secure Retrospective Interference Alignment

   https://doi.org/10.3390/e21111092  

   Seif, Mohamed; Tandon, Ravi; Li, Ming (November 2019, Entropy)

   In this paper, the K-user interference channel with secrecy constraints is considered with delayed channel state information at transmitters (CSIT). We propose a novel secure retrospective interference alignment scheme in which the transmitters carefully mix information symbols with artificial noises to ensure confidentiality. Achieving positive secure degrees of freedom (SDoF) is challenging due to the delayed nature of CSIT, and the distributed nature of the transmitters. Our scheme works over two phases: Phase one, in which each transmitter sends information symbols mixed with artificial noises, and repeats such transmission over multiple rounds. In the next phase, each transmitter uses the delayed CSIT of the previous phase and sends a function of the net interference and artificial noises (generated in previous phase), which is simultaneously useful for all receivers. These phases are designed to ensure the decodability of the desired messages while satisfying the secrecy constraints. We present our achievable scheme for three models, namely: (1) K-user interference channel with confidential messages (IC-CM), and we show that 1 2 ( K - 6 ) SDoF is achievable; (2) K-user interference channel with an external eavesdropper (IC-EE); and 3) K-user IC with confidential messages and an external eavesdropper (IC-CM-EE). We show that for the K-user IC-EE, 1 2 ( K - 3 ) SDoF is achievable, and for the K-user IC-CM-EE, 1 2 ( K - 6 ) is achievable. To the best of our knowledge, this is the first result on the K-user interference channel with secrecy constrained models and delayed CSIT that achieves an SDoF which scales with K , square-root of number of users. 

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3. Multi-Layer Interference Alignment and GDoF of the K-User Asymmetric Interference Channel

   https://doi.org/10.1109/TIT.2021.3071037  

   Chen, Jinyuan (June 2021, IEEE Transactions on Information Theory)
4. Photonic Interference Beyond Two Modes

   https://doi.org/10.1364/QUANTUM.2023.QW4A.3  

   Oliver, Richard; Blau, Miri; Ji, Xingchen; Gutiérrez-Jáuregui, Ricardo; Asenjo-Garcia, Ana; Lipson, Michal; Gaeta, Alexander L (June 2023, Optica Quantum 2.0 Conference and Exhibition)

   We propose multipartite Bragg-scattering to perform all-to-all transformation among N frequency modes, realizing a bosonic N-level system. We demonstrate the N = 3 case illustrating a pathway towards scalability for frequency-domain optical quantum information systems. 

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5. Quantum interference in superposed lattices

   https://doi.org/10.1073/pnas.2315787121  

   Feng, Yejun; Wang, Yishu; Rosenbaum, T. F.; Littlewood, P. B.; Chen, Hua (February 2024, Proceedings of the National Academy of Sciences)

   Charge transport in solids at low temperature reveals a material’s mesoscopic properties and structure. Under a magnetic field, Shubnikov–de Haas (SdH) oscillations inform complex quantum transport phenomena that are not limited by the ground state characteristics and have facilitated extensive explorations of quantum and topological interest in two- and three-dimensional materials. Here, in elemental metal Cr with two incommensurately superposed lattices of ions and a spin-density-wave ground state, we reveal that the phases of several low-frequency SdH oscillations in ${\sigma }_{\mathit{xx}} \left({\rho }_{\mathit{xx}}\right)$and ${\sigma }_{\mathit{yy}} \left({\rho }_{\mathit{yy}}\right)$are no longer identical but opposite. These relationships contrast with the SdH oscillations from normal cyclotron orbits that maintain identical phases between ${\sigma }_{\mathit{xx}} \left({\rho }_{\mathit{xx}}\right)$and ${\sigma }_{\mathit{yy}} \left({\rho }_{\mathit{yy}}\right)$ . We trace the origin of the low-frequency SdH oscillations to quantum interference effects arising from the incommensurate orbits of Cr’s superposed reciprocal lattices and explain the observed $\pi$-phase shift by the reconnection of anisotropic joint open and closed orbits. 

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