报告题目：Coherent Spectroscopy for Quantum Control of Matter

报 告 人：Alan D. Bristow Department of Physics & Astronomy, West Virginia University

报告时间：2015年4月15日10:00

报告地点：理科楼三楼报告厅 (C302)

报告摘要：Quantum control can be achieved in many atomic and chemical settings, for example to enhance product or byproduct branching ratios, direct photocurrents or photoionization channels and enhance mechanisms in photocatalysis. Quantum control primarily uses constructive and destructive interference of quantum pathways between initial and final states to select and controlled the desired process with the amplitude and phase of the incoming light. In this talk, a simple quantum control scheme based on two harmonically related pulses is demonstrated to drive and direct photocurrents in semiconductors[1] and topological insulators[2]. In practice, quantum control is often hindered by insufficient information about the target states. Calculation of the system’s Hamiltonian can even be impossible. In this talk, multidimensional coherent spectroscopy is also used to acquire the Hamiltonian for potassium vapor[3]. This method yields line centers and line widths for all the quantum pathways for a three-level atomic system, such that the full Hamiltonian can be modeled empirically. Multidimensional coherent spectroscopy paves the way for measuring the desired properties of any system in situ, prior to the implementation of a deterministic quantum control scheme. Preliminary results on semiconductors will are also presented[4].

[1]. Costa, L., Betz, M., Spasenovic, M., Bristow, A. D. & Van Driel, H. M. All-optical injection of ballistic electrical currents in unbiased silicon. Nat. Phys. 3, 632–635 (2007).

[2]. Bas, D. A. et al. Coherent control of injection currents in high-quality films of Bi2Se3. Appl. Phys. Lett. 106, 041109 (2015).

[3]. Li, H., Bristow, A. D., Siemens, M. E., Moody, G. & Cundiff, S. T. Unraveling quantum pathways using optical 3D Fourier-transform spectroscopy. Nat. Commun. 4, 1390 (2013).

[4]. Cundiff, S. T., Zhang, T., Bristow, A. D., Karaiskaj, D. & Dai, X. Optical Two-Dimensional Fourier Transform Spectroscopy of Semiconductor Quantum Wells. Acc. Chem. Res. 42, 1423–1432 (2009).