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arXiv:2305.17632 · Physical Review Letters

Programmable Photonic Time Circuits for Highly Scalable Universal Unitaries

Xianji Piao, Sunkyu Yu, Namkyoo Park

Published Mar 5, 2024• 13 citations
arXivHTMLPDF

Abstract

Programmable photonic circuits (PPCs) have garnered substantial interest for their potential in facilitating deep learning accelerations and universal quantum computations. Although photonic computation using PPCs offers ultrafast operation, energy-efficient matrix calculations, and room-temperature quantum states, its poor scalability hinders integration. This challenge arises from the temporally one-shot operation of propagating light in conventional PPCs, resulting in a light-speed increase in device footprints. Here we propose the concept of programmable photonic time circuits, utilizing time-cycle-based computations analogous to gate cycling in the von Neumann architecture and quantum computation. Our building block is a reconfigurable SU(2) time gate, consisting of two resonators with tunable resonances, and coupled via time-coded dual-channel gauge fields. We demonstrate universal U(N) operations with high fidelity using an assembly of the SU(2) time gates, substantially improving scalability from O(N^{2}) to O(N) in terms of both the footprint and the number of gates. This result paves the way for PPC implementation in very large-scale integration.

DOI
10.1103/physrevlett.132.103801

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We introduce the platform for photonic computation using dynamically modulated coupled resonances. By realizing the interference between the couplings with tunable gauge fields, we implement reconfigurable and universal SU(2) time gates, which are the unit elements for achieving universal U(NNN) operations in an adaptable manner. In the talk, the application of the proposed platform to quantum gates and quantum-optical analogy as examples.
I introduce time-reflection photonic quantum computing, an architecture in which qubits are encoded in pairs of counter-propagating photonic modes that evolve along dual temporal channels. By engineering gates that implement time reflections between these channels, the dynamics become intrinsically reversible, causing dominant error processes—dephasing, photon loss, and phase noise—to be continuously unwound and rephased without external feedback or active error-correction cycles. This built-in self-correction enables ultra-low-energy quantum information processing at room temperature and substantially reduces hardware complexity compared with superconducting or trapped-ion platforms. My analytical modeling and numerical simulations show that time-reflection circuits preserve coherence over large depths, maintain high fidelities in the presence of realistic noise, and support the implementation of a universal gate set using photonic resources. These results establish time-reflection photonic architectures as a promising, energy-efficient route toward scalable quantum information processing.
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Abstract I introduce time-reflection photonic quantum computing, an architecture in which qubits are encoded in pairs of counterpropagating photonic modes that evolve along dual temporal channels. By engineering gates that implement time reflections between these channels, the dynamics become intrinsically reversible, causing dominant error processes—dephasing, photon loss, and phase noise—to be continuously unwound and rephased without external feedback or active errorcorrection cycles. This builtin selfcorrection enables ultralowenergy quantum information processing at room temperature and substantially reduces hardware complexity compared with superconducting or trappedion platforms. My analytical modeling and numerical simulations show that timereflection circuits preserve coherence over large depths, maintain high fidelities in the presence of realistic noise, and support the implementation of a universal gate set using photonic resources. These results establish timereflection photonic architectures as a promising, energyefficient route toward scalable quantum information processing.
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