Programme

O.25 -- Oral, VCTP-51

Date: Tuesday, 4 August 2026

Time: 15:20 - 15:40

Compact indicator set of intrinsic molecular asymmetry in high-order harmonic generation from polar molecules

Kim-Ngan H. Nguyen (1, 2), Thanh Tran (3), Doan-An Trieu (1, 2), Duong D. Hoang-Trong (4, 5), Cam-Tu Le (6, 7), Lan Nguyen Tran (8, 9), Van-Hoang Le (3), and Ngoc-Loan Phan (3)

(1) Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City 70000, Vietnam (2) Faculty of Natural Sciences, Duy Tan University, Da Nang City 50000, Vietnam (3) Computational Physics Key Laboratory K002, Department of Physics, Ho Chi Minh City University of Education, Ho Chi Minh City 72722, Vietnam (4) Simulation in Materials Science Research Group, Science and Technology Advanced Institute, Van Lang University, Ho Chi Minh City, Vietnam (5) Faculty of Applied Technology,Van Lang School of Technology, Van Lang University, Ho Chi Minh City, Vietnam (6) Atomic Molecular and Optical Physics Research Group, Institute for Advanced Study in Technology, Ton Duc Thang University, Ho Chi Minh City 72912, Vietnam (7) Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City 72912, Vietnam (8) University of Science, Vietnam National University, Ho Chi Minh City 70000, Vietnam (9) Vietnam National University, Ho Chi Minh City 70000, Vietnam

High-order harmonic generation (HHG) is a powerful tool for probing molecular structure [1] and ultrafast electron dynamics [2]. For oriented polar molecules, the breaking of the spatial symmetry of the laser-target system leads to the simultaneous emission of both odd and even harmonics [3, 4], which encode the intrinsic asymmetry of the molecule [3-6]. However, quantitatively characterizing this asymmetry by connecting spectral measurements with microscopic emission dynamics on the sub-cycle timescale remains an open challenge [5, 6]. Specifically, existing retrieval approaches remain highly indirect and not self-contained, as they rely heavily on auxiliary pre-calculated structural inputs [4, 5] or operationally involved inverse numerical procedures [6]. In this work, we establish a complete set of indicators - namely, the odd-even HHG intensity and phase difference observed in the spectral - creating a direct and invertible mapping to the amplitude and phase of attosecond bursts in the time domain. This theoretical framework is validated by solving the time-dependent Schrödinger equation (TDSE) for the CO molecule, confirming that this set of indicators is an intrinsic signature of the molecular structure and is largely insensitive to laser parameters. Hence, this approach enables direct reconstruction of attosecond-burst asymmetries from experimentally accessible odd-even HHG observables.

Presenter: Tran Thanh