The research of this Emeritus Group focuses on the three-dimensional vector patterns of optical modes and on their quantized excitation. In the year 2000, when Gerd Leuchs suggested the establishment of a Research Group to the Max Planck Society he also proposed the possibility of focussing light tighter by polarization pattern engineering. The first experimental verification of this effect in 2003 was also the first paper published by the newly established Max Planck Research Group at Erlangen. The following years have seen an unprecedented worldwide increase of research into radially polarized and related light modes. The topic was of course also continued in this division, leading to projects on the transverse angular momentum of light, on localisation of particles and on non-factorable mode patterns resembling entanglement and including applications e.g. in plasmonics. The other line of research on quantized excitations goes back to Gerd Leuchs' observation of photon anti bunching in 1979 and of squeezed light in second harmonic generation in 1990 and has led to numerous on-going projects on quantum communication, including the generation of temporally tailored single photon wave packets using a whispering gallery mode resonator, the generation of bright squeezed vacuum states and the distribution of quantum keys via satellites. In one project both research lines are combined to study the efficiency of the coupling of quantum light to a single atom. The goal is two-fold: to experimentally demonstrate the reversibility of spontaneous emission and to provide photon-photon interaction at the highest bandwidth allowed by nature.
The research of this Emeritus Group focuses on the three-dimensional vector patterns of optical modes and on their quantized excitation. There are six groups working on different research-topics within the field of optics and information.
The membership of Optica, formerly OSA, the leading organization for the advancement of optics and photonics worldwide, has elected Gerd Leuchs,…
Chiral light-matter-interaction is an intriguing phenomenon, which links the geometry and symmetry of certain molecules or nanostructures with their…
Efficient generation of temporally shaped photons using nonlocal spectral filtering
V. Averchenko, D. Sych, C. Marquardt, G. Leuchs
We study the generation of single-photon pulses with the tailored temporal shape via nonlocal spectral filtering. A shaped photon is heralded from a time-energy entangled photon pair upon spectral filtering and time-resolved detection of its entangled counterpart. We show that the temporal shape of the heralded photon is defined by the time-inverted impulse response of the spectral filter and does not depend on the heralding instant. Thus one can avoid postselection of particular heralding instants and achieve a substantially higher heralding rate of shaped photons as compared to the generation of photons via nonlocal temporal modulation. Furthermore, the method can be used to generate shaped photons with a coherence time in the ns-μs range and is particularly suitable to produce photons with the exponentially rising temporal shape required for efficient interfacing to a single quantum emitter in free space.
Microscale Generation of Entangled Photons without Momentum Conservation
Cameron Okoth, Andrea Cavanna, Tomas Santiago-Cruz, Maria Chekhova
We report, for the first time, the observation of spontaneous parametric down-conversion (SPDC) free of phase matching (momentum conservation).We alleviate the need to conserve momentum by exploiting the position-momentum uncertainty relation and using a planar geometry source, a 6 μm thick layer of lithium niobate. Nonphase-matched SPDC opens up a new platform on which to investigate fundamental quantum effects but it also has practical applications. The ultrasmall thickness leads to a frequency spectrum an order of magnitude broader than that of phase-matched SPDC. The strong two-photon correlations are still preserved due to energy conservation. This results in ultrashort temporal correlation widths and huge frequency entanglement. The studies we make here can be considered as the initial steps into the emerging field of nonlinear quantum optics on the microscale and nanoscale.
Interaction of light carrying orbital angular momentum with a chiral dipolar scatterer
Pawel Wozniak, Israel De León, Katja Höflich, Gerd Leuchs, Peter Banzer
The capability to distinguish the handedness of circularly polarized light is a well-known intrinsic property of a chiral nanostructure. It is a long-standing controversial debate, however, whether a chiral object can also sense the vorticity, or the orbital angular momentum (OAM), of a light field. Since OAM is a non-local property, it seems rather counter-intuitive that a point-like chiral object could be able to distinguish the sense of the wave-front of light carrying OAM. Here, we show that a dipolar chiral nanostructure is indeed capable of distinguishing the sign of the phase vortex of the incoming light beam. To this end, we take advantage of the conversion of the sign of OAM, carried by a linearly polarized Laguerre-Gaussian beam, into the sign of optical chirality upon tight focusing. Our study provides for a deeper insight into the discussion of chiral light-matter interactions and the respective role of OAM.