Few-photon coherent nonlinear optics with a single molecule

The extraordinary success in laser cooling, trapping, and coherent manipulation of atoms has energized the efforts in extending this exquisite control to molecules. Not only are molecules ubiquitous in nature, but the control of their quantum states offers unparalleled access to fundamental constants and possible physics beyond the Standard Model. Quantum state manipulation of molecules can enable high-precision measurements including tests of fundamental symmetries and searc...

Nonlinear spectroscopy with quantum entangled photons is an emerging field of research that holds the promise to achieve a superior signal-to-noise ratio and effectively isolate many-body interactions. Photon sources used for this purpose however lack the frequency tunability and spectral bandwidth demanded by contemporary molecular materials. Here, we present design strategies for efficient spontaneous parametric downconversion to generate biphoton states with adequate spect...

Optical nonlinearities - how light-matter interactions are influenced by previous interactions with photons, are key resources in the contemporary photonics toolbox, relevant to quantum gate operations and all-optical switches. Optical nonlinearities of materials are often controlled at the microscopic level by chemical modification, which makes on-the-fly manipulation of such response challenging. Tunability of optical nonlinearities in the mid-IR is even less developed, hin...

The theory of the fundamental limits (TFL) of nonlinear optics is a powerful tool for experimentalists seeking to create molecules and materials with large responses, and for theorists who are seeking to understand how the basic elements of quantum theory delineate the boundaries within which these searches should be conducted. On a practical level, the TFL provides a metric for measuring the performance or 'goodness' of new molecules, relative to what is possible. Exploratio...

We demonstrate two-photon interference using two remote single molecules as bright solid-state sources of indistinguishable photons. By varying the transition frequency and spectral width of one molecule, we tune and explore the effect of photon distinguishability. We discuss future improvements on the brightness of single-photon beams, their integration by large numbers on chips, and the extension of our experimental scheme to coupling and entanglement of distant molecules.

The control and manipulation of quantum-entangled non-local states is a crucial step for the development of quantum information processing. A promising route to achieve such states on a wide scale is to couple solid-state quantum emitters through their coherent dipole-dipole interactions. Entanglement in itself is challenging, as it requires both nanometric distances between emitters and nearly degenerate electronic transitions. Implementing hyperspectral imaging to identify ...

The generation and control of entanglement in a quantum mechanical system is a critical element of nearly all quantum applications. Molecular systems are a promising candidate, with numerous degrees of freedom able to be targeted. However, knowledge of inter-system entanglement mechanisms in such systems is limited. In this work, we demonstrate the generation of entanglement between vibrational degrees of freedom in molecules via strong coupling to a cavity mode driven by a w...

The successful development of future photonic quantum technologies heavily depends on the possibility of realizing robust, reliable and, crucially, scalable nanophotonic devices. In integrated networks, quantum emitters can be deployed as single-photon sources or non-linear optical elements, provided their transition linewidth is broadened only by spontaneous emission. However, conventional fabrication approaches are hardly scalable, typically detrimental for the emitter cohe...

Conventional wisdom holds that quantum effects are fragile and can be destroyed by loss. Here, contrary to general belief, we show how to realize quantum revival of optical correlations at the single-photon level with the help of loss. We find that, accompanying loss-induced transparency of light in a nonlinear optical-molecule system, quantum suppression and revival of photonic correlations can be achieved. Specifically, below critical values, adding loss into the system lea...

Plasmonic waveguides offer the unique possibility to confine light far below the diffraction limit. Past room temperature experiments of single quantum emitters coupled to such waveguides have mainly focused on efficient channelling of the spontaneous emission into waveguide modes after a linear optical excitation. However, only the simultaneous interaction of the emitter with multiple plasmonic fields would lead to functionality in a plasmonic circuit. Here, we demonstrate t...