Browsing by Author "Gulbahar, Burhan"

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Encrypted quantum state tomography with phase estimation for quantum Internet
(SPRINGER, 2023) Burhan Gulbahar; Gulbahar, Burhan
Quantum state tomography (QST) is a fundamental tool requiring privacy in future distributed systems where unknown states are measured for extracting information. Gentle measurement and differential privacy (DP)-based privacy solutions minimize the damage on unknown state and leakage about the quantum information respectively. In this article we propose a fundamentally different design for privacy-preserving QST in a multi-party setting. We assume that Alice delegates QST task of a distant source for which she has no access to a third-party player Bob accessing to the source while preserving the source privacy against the operations realized by Bob. Encrypted QST algorithm is proposed which encodes or maps source computational basis states by exploiting phase estimation and feature mapping concept of quantum machine learning (QML). Bob maps basis states to eigenvalues of a specially designed unitary operator in an entangled manner with his ancillary qubits while teleporting the source qubits back to Alice before applying conventional QST. Encoding mechanism is conjectured as having NP-hard decoding complexity based on difficulty of subset-sum problem combined with Hadamard transform. Linear optical design and quantum circuit implementations are presented for future experiments in noisy intermediate-scale quantum (NISQ) devices. Theoretical and numerical supporting evidences are proposed supporting the proposed eigenstructure. EQST promises further applications for multiple source classification tasks and as a novel feature mapping method for future data embedding tasks in QML.
Citation - WoS: 10
Citation - Scopus: 9
Maximum-Likelihood Detection With QAOA for Massive MIMO and Sherrington-Kirkpatrick Model With Local Field at Infinite Size
(Institute of Electrical and Electronics Engineers Inc., 2024) Burhan Gulbahar; Gulbahar, Burhan
Quantum-approximate optimization algorithm (QAOA) is promising in Noisy Intermediate-Scale Quantum (NISQ) computers with applications for NP-hard combinatorial optimization problems. It is recently utilized for NP-hard maximum-likelihood (ML) detection problem with challenges of optimization simulation and performance analysis for n × n multiple-input multiple output (MIMO) systems with large n. QAOA is recently applied by Farhi et al. on infinite size limit of Sherrington-Kirkpatrick (SK) model with a cost model including only quadratic terms. In this article we extend the model by including also linear terms and then realize SK modeling of massive MIMO ML detection. The proposed design targets near ML performance while with complexity including O 16p initial operations independent from problem instance and size n for optimizing QAOA angles and On2\p quantum operations for each instance. We provide both optimized and extrapolated angles for p ϵ [1 14] and signal-to-noise (SNR) < 12 dB achieving near-optimum ML performance with p ≥ 4 for 25 × 25 and 12 × 12 MIMO systems modulated with BPSK and QPSK respectively. We present two conjectures about concentration properties of QAOA and near-optimum performance for next generation massive MIMO systems covering n < 300. © 2024 Elsevier B.V. All rights reserved.
Citation - WoS: 1
Citation - Scopus: 1
Strong simulation of tracking single photons with which-way-detectors in linear optics
(IOP Publishing Ltd, 2023) Burhan Gulbahar; Gulbahar, Burhan
Which-way-detectors (WWDs) are path-entangled detectors characterizing mutual exclusivity between path information and interference visibility in wave-particle duality experiments. We show surprisingly that WWDs allow to utilize single photons distinguishable in time domain to realize linear optical circuits where tracking their paths is exponentially hard for strong simulation analogous to rectangular lattice based Ising models. Distinguishable photons have scalability advantages of generation and detection compared with indistinguishable photons by promising both theoretical and experimental improvements in linear optical computing including boson sampling. We calculate strong simulation complexities by using variable elimination (VE) method for undirected graphs related to tensor network contraction for quantum circuits and recursive Feynman path-integral (RFPI) method to reduce space complexity. Two designs include either a single photon touring m times or m single photons propagating sequentially through an optical circuit composed of n beam splitters and phase shifters entangled with n WWDs. VE method for tracking results in undirected graphs matching with (2m - 1) x (n + 1) and m x (n + 1) lattice Ising models with computational complexities of O(m n 2(min)((2 m - 1) (n + 1))) and O(m n 2(min(m n + 1))) in time and O(2(min(2 m - 1 n + 1))) and O(2(min(m n + 1))) in space for single and multi-photon based designs respectively. We exploit RFPI method for m >> n to reduce space complexities to polynomial levels with respect to n and log m. Probability amplitude of specific cases of multi-photon design is represented in terms of Ising partition function with purely imaginary weights to characterize sampling complexity. Open issues about sampling complexity and experimental implementation of multi-WWD set-ups are discussed.
Citation - WoS: 1
Citation - Scopus: 1
Theory and Experiment of Spatial Light Modulation and Demodulation With Multi-Plane Diffraction and Applications
(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2023) Burhan Gulbahar; Ahmet Emrecan Oksuz; Oksuz, Ahmet Emrecan; Gulbahar, Burhan
Spatial light modulation enhances capacity of optical communications by modulating spatial amplitude phase and polarization degrees of freedom with recent success of orbital angular momentum based architectures. There is a hardware challenge to demodulate large symbol families or high order symbols requiring a general design of spatial light demodulation. Multi-plane diffraction (MPD) recently introduced for improving spatial modulation capabilities in free space optical channels promises utilization at the receiver side as a demodulator. In this article we theoretically model numerically simulate and experimentally implement spatial light demodulation based on MPD. Numerical simulations and experimental implementations verify capabilities of MPD for increasing inter-symbol distances at the detector front-end. We obtain approximately two times improvement compared with direct detection for basic design including three diffraction planes as a proof-of-concept and improved performance with increasing number of diffraction planes compared with state-of-the-art single-plane diffraction (SPD) based interferometric receivers. Besides that we perform for the first time experimental implementation of MPD based spatial light modulation. In addition symmetric-key cryptography application of the proposed system is theoretically presented with low decoder complexity while numerical simulations promise high performance security against intruders. MPD based design is practically applicable and promising for diverse optical architectures including both communications and cryptography as a low-cost low hardware complexity passive and high performance design.