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Wang N, Feng F, Ping Wang G. Achieving bi-anisotropic coupling through uniform temporal modulations without inversion symmetry disruption. OPTICS LETTERS 2024; 49:2493-2496. [PMID: 38691752 DOI: 10.1364/ol.518816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 04/10/2024] [Indexed: 05/03/2024]
Abstract
Temporal modulations provide a new approach for realizing metamaterials. In this study, through the imposition of uniform temporal modulations, we achieve two types of reciprocal bi-anisotropic metamaterials. Notably, these achievements do not rely on any spatial modulation, preserving inversion symmetry at any instantaneous time. This stands in sharp contrast to the scenario of traditional bi-anisotropic metamaterials, where the disruption of inversion symmetry by spatial arrangements is necessary. Conditions for realizing nonzero bi-anisotropic coupling are discussed and verified through full-wave simulations. Our work will stimulate research in the field of temporal bi-anisotropic metamaterials, as well as the application of temporal modulations in manipulating photonic spin angular momentum.
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Piao X, Yu S, Park N. Programmable Photonic Time Circuits for Highly Scalable Universal Unitaries. PHYSICAL REVIEW LETTERS 2024; 132:103801. [PMID: 38518334 DOI: 10.1103/physrevlett.132.103801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 02/01/2024] [Indexed: 03/24/2024]
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.
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Affiliation(s)
- Xianji Piao
- Wave Engineering Laboratory, School of Electrical and Computer Engineering, University of Seoul, Seoul 02504, Korea
| | - Sunkyu Yu
- Intelligent Wave Systems Laboratory, Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea
| | - Namkyoo Park
- Photonic Systems Laboratory, Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea
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Liu W, Liu Q, Ni X, Jia Y, Ziegler K, Alù A, Chen F. Floquet parity-time symmetry in integrated photonics. Nat Commun 2024; 15:946. [PMID: 38297005 PMCID: PMC10830577 DOI: 10.1038/s41467-024-45226-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 01/16/2024] [Indexed: 02/02/2024] Open
Abstract
Parity-time (PT) symmetry has been unveiling new photonic regimes in non-Hermitian systems, with opportunities for lasing, sensing and enhanced light-matter interactions. The most exotic responses emerge at the exceptional point (EP) and in the broken PT-symmetry phase, yet in conventional PT-symmetric systems these regimes require large levels of gain and loss, posing remarkable challenges in practical settings. Floquet PT-symmetry, which may be realized by periodically flipping the effective gain/loss distribution in time, can relax these requirements and tailor the EP and PT-symmetry phases through the modulation period. Here, we explore Floquet PT-symmetry in an integrated photonic waveguide platform, in which the role of time is replaced by the propagation direction. We experimentally demonstrate spontaneous PT-symmetry breaking at small gain/loss levels and efficient control of amplification and suppression through the excitation ports. Our work introduces the advantages of Floquet PT-symmetry in a practical integrated photonic setting, enabling a powerful platform to observe PT-symmetric phenomena and leverage their extreme features, with applications in nanophotonics, coherent control of nanoscale light amplification and routing.
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Affiliation(s)
- Weijie Liu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, 250100, Jinan, China
| | - Quancheng Liu
- Department of Physics, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Xiang Ni
- School of Physics, Central South University, 410083, Changsha, Hunan, China
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA
| | - Yuechen Jia
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, 250100, Jinan, China
| | - Klaus Ziegler
- Institut für Physik, Universität Augsburg, 86135, Augsburg, Germany
| | - Andrea Alù
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031, USA.
- Physics Program, Graduate Center, City University of New York, New York, NY, 10016, USA.
| | - Feng Chen
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, 250100, Jinan, China.
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Zhou L, Zhang DJ. Non-Hermitian Floquet Topological Matter-A Review. ENTROPY (BASEL, SWITZERLAND) 2023; 25:1401. [PMID: 37895522 PMCID: PMC10606436 DOI: 10.3390/e25101401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/19/2023] [Accepted: 09/27/2023] [Indexed: 10/29/2023]
Abstract
The past few years have witnessed a surge of interest in non-Hermitian Floquet topological matter due to its exotic properties resulting from the interplay between driving fields and non-Hermiticity. The present review sums up our studies on non-Hermitian Floquet topological matter in one and two spatial dimensions. We first give a bird's-eye view of the literature for clarifying the physical significance of non-Hermitian Floquet systems. We then introduce, in a pedagogical manner, a number of useful tools tailored for the study of non-Hermitian Floquet systems and their topological properties. With the aid of these tools, we present typical examples of non-Hermitian Floquet topological insulators, superconductors, and quasicrystals, with a focus on their topological invariants, bulk-edge correspondences, non-Hermitian skin effects, dynamical properties, and localization transitions. We conclude this review by summarizing our main findings and presenting our vision of future directions.
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Affiliation(s)
- Longwen Zhou
- College of Physics and Optoelectronic Engineering, Ocean University of China, Qingdao 266100, China
- Key Laboratory of Optics and Optoelectronics, Qingdao 266100, China
- Engineering Research Center of Advanced Marine Physical Instruments and Equipment of MOE, Qingdao 266100, China
| | - Da-Jian Zhang
- Department of Physics, Shandong University, Jinan 250100, China
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Wang X, Mirmoosa MS, Asadchy VS, Rockstuhl C, Fan S, Tretyakov SA. Metasurface-based realization of photonic time crystals. SCIENCE ADVANCES 2023; 9:eadg7541. [PMID: 37018399 PMCID: PMC10075962 DOI: 10.1126/sciadv.adg7541] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/08/2023] [Indexed: 06/19/2023]
Abstract
Photonic time crystals are artificial materials whose electromagnetic properties are uniform in space but periodically vary in time. The synthesis of these materials and experimental observation of their physics remain very challenging because of the stringent requirement for uniform modulation of material properties in volumetric samples. In this work, we extend the concept of photonic time crystals to two-dimensional artificial structures-metasurfaces. We demonstrate that time-varying metasurfaces not only preserve key physical properties of volumetric photonic time crystals despite their simpler topology but also host common momentum bandgaps shared by both surface and free-space electromagnetic waves. On the basis of a microwave metasurface design, we experimentally confirmed the exponential wave amplification inside a momentum bandgap and the possibility to probe bandgap physics by external (free-space) excitations. The proposed metasurface serves as a straightforward material platform for realizing emerging photonic space-time crystals and as a realistic system for the amplification of surface-wave signals in future wireless communications.
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Affiliation(s)
- Xuchen Wang
- Department of Electronics and Nanoengineering, Aalto University, Espoo, Finland
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | | | - Viktar S. Asadchy
- Department of Electronics and Nanoengineering, Aalto University, Espoo, Finland
- Ginzton Laboratory and Department of Electrical Engineering, Stanford University, USA
| | - Carsten Rockstuhl
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Shanhui Fan
- Ginzton Laboratory and Department of Electrical Engineering, Stanford University, USA
| | - Sergei A. Tretyakov
- Department of Electronics and Nanoengineering, Aalto University, Espoo, Finland
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