学术报告（2009年9月23日）

发布时间: 2009-09-18 　　浏览次数: 37

学术报告

下周三（9月23日）的报告将于下午3：20开始，到4：30结束，光学楼525。报告人是徐雷老师邀请的意大利的Lorenzo Marrucci教授（Università di Napoli Federico II）。关于更多报告内容，请登录下面的网页查阅详情：

http://www.optics.fudan.edu.cn/colloquium/2009fall/colloquium.htm

这次报告的题目和摘要是

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Rotating photons:

conversion of the angular momentum of light from the spin form to the orbital form and vice versa, Hong-Ou-Mandel quantum interference, and quantum cloning of single photon vortices

Lorenzo Marrucci

Dipartimento di Scienze Fisiche, Università di Napoli Federico II, Napoli, ITALY

A beam of light, or even a single photon, can carry two different forms of angular momentum: the “spin” form, associated with a circular polarization, and the “orbital” form, associated with a helical wavefront and with an optical vortex at the beam core.¹ Both forms of angular momentum can be coupled with matter and thus induce the rotation of a small particle. A few years ago, we have found that an optical medium that is both birefringent and inhomogeneous can couple these two forms of angular momentum to each other and thus give rise to a conversion from one form to the other.² A novel optical element having this conversion capability, named “q-plate”, has been thus developed by us using patterned liquid crystals technology.^{2-5 A q-plate allows a much more flexible control of the orbital angular momentum (OAM) of light, both at a classical and quantum level, than other existing methods. For example, the possibility of transferring a qubit of quantum information encoded in a single photon from the polarization (spin) degree of freedom to the OAM and vice versa has been demonstrated.6,7} This quantum transfer works well even with pairs of photons exhibiting quantum correlations.⁶ Exploiting this good control of the OAM of photons, we have then demonstrated for the first time the Hong-Ou-Mandel quantum coalescence effect of two OAM-carrying photons impinging on a beam-splitter and the optimal quantum cloning of the OAM quantum state of a single photon.⁸

1. “Advances in optical angular momentum”, S. Franke-Arnold, L. Allen, M. Padgett, Laser & Photon. Rev. 2, 299 (2008).

2. “Optical spin-to-orbital angular momentum conversion in inhomogeneous anisotropic media”, L. Marrucci, C. Manzo, D. Paparo, Phys. Rev. Lett. 96, 163905 (2006).

3. “Pancharatnam-Berry phase optical elements for wavefront shaping in the visible domain: switchable helical modes generation”, L. Marrucci, C. Manzo, D. Paparo, Appl. Phys. Lett. 88, 221102 (2006)

4. “Light propagation in a birefringent plate with topological charge”, E. Karimi, B. Piccirillo, L. Marrucci, E. Santamato, Opt. Lett. 34, 1225-1227 (2009).

5. “Efficient generation and sorting of orbital angular momentum eigenmodes of light by thermally tuned q-plates”, E. Karimi, B. Piccirillo, E. Nagali, L. Marrucci, E. Santamato, Appl. Phys. Lett. 94, 231124 (2009).

6. “Quantum information transfer from spin to orbital angular momentum of photons”, E. Nagali, F. Sciarrino, F. De Martini, L. Marrucci, B. Piccirillo, E. Karimi, E. Santamato, Phys. Rev. Lett. 103, 013601 (2009).

7. “Polarization control of single photon quantum orbital angular momentum states”, E. Nagali, F. Sciarrino, F. De Martini, B. Piccirillo, E. Karimi, L. Marrucci, E. Santamato, submitted.

8. “Optimal quantum cloning of orbital angular momentum photon qubits via Hong-Ou-Mandel coalescence”, E. Nagali, F. Sciarrino, L. Sansoni, F. De Martini, L. Marrucci, B. Piccirillo, E. Karimi, E. Santamato, submitted.

请大家准时参加。另外，报告前15分钟在光学楼500房间提供茶叶和一次性杯子，请大家自己动手泡茶喝；同时，也提供老师和同学们面对面交流的机会。谢谢。