Feb 07, 2019 3:45 pm - Nielsen Hall 170 - Colloquium
Xiao-Feng Qian - The Institute of Optics, and Department of Physics & Astronomy University of Rochester
Quantum-Classical Links in Optics

The issue of connection and boundary between quantum and classical is of great fundamental and prac- tical importance. It has always been one of the leading topics in physics research ever since the born of quantum mechanics. The field of quantum information science is one of the most prevailing modern ex- amples as an effort of searching and utilizing connections between quantum and classical information [1]. Fantastic applications in various subfields such as quantum computing, quantum communication, quantum cryptography have been proposed and extensively explored in the past few decades. Remarkably, new links beyond information, are emerging. Recently, it has been demonstrated in detail that properties such as en- tanglement, coherence, etc., that are widely considered as uniquely quantum, can also be found to exist in classical optical fields [2]. This new emerging field can be called “Classically Entangled Optics”, and it has stimulated various intriguing theoretical and experimental examinations. Both fundamental issues (e.g., Bell violation, wave-particle duality, optical polarization theory, hidden coherence) and practical applications (e.g., optical metrology, optical sensing, analog of teleportation) based on this new recognition are being actively investigated [2]. It is amazing that even a century after the birth of quantum mechanics, new issues of quantum-classical links are still emerging.

In this talk, I will discuss my recent research work in the perspective of quantum-classical links through way of the emerging field “Classically Entangled Optics”. A brief introduction of this field is given explaining quantum-classical analogs in optics. It is then followed by a detailed discussion of our recent advances in the investigation of Bohr’s complementarity [3] as an illustration of how the concepts of entanglement, coherence, wave-particle duality find their places in both classical coherence optics [4] and in quantum single photons [5]. To summarize, a brief outlook of my research is given.


  1. [1]  M.A. Nielsen and I.L. Chuang, Quantum Computation and Quantum Information, Cambridge Univ. Press, (2000).

  2. [2]  SeeabriefoverviewinX.-F.Qian,A.N.Vamivakas,andJ.H.Eberly,“EmergingConnections:Classical and Quantum Optics”, Optics & Photonics News, 28 (10), 34-41 (2017).

  3. [3]  N. Bohr, Naturwissenschaften 16, 245 (1928); “The Quantum Postulate and the Recent Development of Atomic Theory,” Nature 121, 580 (1928).

  4. [4]  X.-F. Qian, A.N. Vamivakas, and J.H. Eberly, “Entanglement limits duality and vice versa”, Optica 5, 942 (2018); J. H. Eberly, X.-F. Qian, and A. N. Vamivakas, ”Polarization coherence theorem,” Optica 4, 1113-1114 (2017).

  5. [5]  X.-F. Qian, K. Konthasinghe, S. K. Manikandan, D. Spiecker, A. N. Vamivakas, and J. H. Eberly, “Coherence without Complementarity”, submitted to Nature (2019); X.-F. Qian and G. S. Agarwal, “Are Quantum Objects Born with Duality?”, submitted to Physical Review Letters (2019).