Ultrafast modulation of vibrational polaritons for controlling the quantum field statistics at mid-infrared frequencies

Controlling the quantum field statistics of confined light is a long-standing goal in integrated photonics. We show that by coupling molecular vibrations with a confined mid-infrared cavity vacuum, the photocount and quadrature field statistics of the cavity field can be reversibly manipulated over sub-picosecond timescales. The mechanism involves changing the cavity resonance frequency through a modulation of the dielectric response of the cavity materials using femtosecond UV pulses. For a single anharmonic molecular vibration in an infrared cavity under ultrastrong coupling conditions, the pulsed modulation of the cavity frequency can adiabatically produce mid- infrared light that is simultaneously sub-Poissonian and quadrature squeezed, depending on the dipolar behavior of the vibrational mode. For a vibration-cavity system in strong coupling, non-adiabatic polariton excitations can be produced after the frequency modulation pulse is over, when the system is initially prepared in the lower polariton state. We propose design principles for the generation of mid-infrared quantum light by analyzing the dependence of the cavity field statistics on the shape of the electric dipole function of the molecule, the cavity detuning at the modulation peak and the anharmonicity of the Morse potential. Feasible experimental implementations of the modulation scheme are suggested. This work paves the way for the development of molecule-based mid-infrared quantum optical devices at room temperature.

Asymmetric topological pumping in nonparaxial photonics

Topological photonics was initially inspired by the quantum-optical analogy between the Schrödinger equation for an electron wavefunction and the paraxial equation for a light beam. Here, we reveal an unexpected phenomenon in topological pumping observed in arrays of nonparaxial optical waveguides where the quantum-optical analogy becomes invalid. We predict theoretically and demonstrate experimentally an asymmetric topological pumping when the injected field transfers from one side of the waveguide array to the other side whereas the reverse process is unexpectedly forbidden. Our finding could open an avenue for exploring topological photonics that enables nontrivial topological phenomena and designs in photonics driven by nonparaxiality.

PR39_FellowshipResearchReport

Summary of a Project Outcomes report of research funded by a PhD Fellowship Award from IBM, in the area of integrated photonics and quantum optical communications.

PR38 Progress Towards Integrated Photon-Pair Sources and Their Applications (1640968-Y5)

The objective of this project was to make significant advances in quantum optical communications through the design, fabrication and demonstration of novel devices at the microchip scale. The principal goal of the device sub-project was to develop key building blocks for photonic microchips that are energy-efficient, leverages modern micro-fabrication platforms, reduces operational complexity and improve scalability with the potential for future adoption by industry. Summary of a Project Outcomes report of research funded by the U.S. National Science Foundation under Project Number 1640968 (Year 5).

Piloting a full-year, optics-based high school course on quantum computing

Quantum computing was once regarded as a mere theoretical possibility, but recent advances in engineering and materials science have brought practical quantum computers closer to reality. Currently, representatives from industry, academia, and governments across the world are working to build the educational structures needed to produce the quantum workforce of the future. Less attention has been paid to growing quantum computing capacity at the high school level. This article details work at The University of Texas at Austin to develop and pilot the first full-year high school quantum computing class. Over the course of two years, researchers and practitioners involved with the project learned several pedagogical and practical lessons that can be helpful for quantum computing course design and implementation at the secondary level. In particular, we find that the use of classical optics provides a clear and accessible avenue for representing quantum states and gate operators and facilitates both learning and the transfer of knowledge to other Science, Technology, and Engineering (STEM) skills. Furthermore, students found that exploring quantum optical phenomena prior to the introduction of mathematical models helped in the understanding and mastery of the material.

Quantum optical analysis of squeezed state of light through dispersive non-Hermitian optical bilayers

We investigate the propagation of a normally incident squeezed coherent state of light through dispersive non-Hermitian optical bilayers, particularly at a frequency that the bilayers hold parity-time (PT) symmetry. To check the realization of PT-symmetry in quantum optics, we reveal how dispersion and loss/gain-induced noises and thermal effects in such bilayers can affect quantum features of the incident light, such as squeezing and sub-Poissonian statistics. The numerical results show thermally-induced noise at room temperature has an insignificant effect on the propagation properties in these non-Hermitian bilayers. Moreover, tuning the bilayers’ loss/gain strength, we show that the transmitted squeezed coherent states through the structure can retain to some extent their nonclassical characteristics, specifically for the frequencies far from the emission frequency of the gain layer. Furthermore, we demonstrate, only below a critical value of gain, quantum optical effective medium theory can correctly predict the propagation of quantized waves in non-Hermitian and PT-symmetric bilayers.

Fluorescence blinking in MoS2 atomic layers by single photon energy transfer

The quantum optical phenomena, such as single photon emission, in two-dimensional (2D) transition metal dichalcogenides (TMDCs) have triggered extensive researches on 2D material-based quantum optics and devices. By far, most reported quantum optical emissions in TMDCs are based on atomic defects in the material or the local confinement of excitons by introducing local stain or potential. In contrast, energy transfer between two materials could also manipulate the photon emission behaviors in materials, even at the single photon level. Along with the single-photon emission nature of zero-dimensional (0D) quantum dots (QDs) at room temperature, constructing a 0D-2D hybrid heterostructure may provide an effective way to regulate the quantum states related optical emissions of TMDCs. Here, we report on fluorescence blinking, a quantum phenomenon, from MoS2 atomic layers in QD/ MoS2 heterostructure at room temperature. We demonstrate the single-photon nature of the QDs in heterostructures by second-order photon correlation measurements. Based on the transient PL spectroscopy and PL time trajectories, we attribute the fluorescence blinking behavior in MoS2 to the single photon energy transfer from QD to MoS2. Our work opens the possibility to achieve correlated quantum emitters in TMDCs at room temperature by controlling the energy transfer between QD and TMDCs.

Comparative Analysis of Spin, Paths, Temporal, and Spatial Modes

Research on optical modes, such as orbital, temporal, or parity, bring much attention, for these new degrees of freedom allow larger quantum communication alphabets. Each lab usually adapts the Bloch or Poincare sphere to their experiment or light mode. This takes an extra effort and time and produces a plethora of spheres and notations. Yet, we miss a common framework or convention valid among diverse physical-modes. We aim to unite in one representation the best points from many different spheres. Such common-sphere could also help to compare distant experiments, for an intuitive understanding of quantum optical states. We built a common representation by mathematically aligning the Hilbert space and a three dimensional color space. We define a unique color for each one of the three Poincare axes and positive Pauli vectors. Beyond three primary colors and states, our equations associate each Hilbert state to a specific tonality, among the infinite combinations in Color space. These maths achieve a new ability to unequivocally represent any quantum state by its precise combination of colors. Thus, with these equations, quantum states ‘yellow’ or ‘magenta’ are not mere names, rather each one denotes an exact superposition in Hilbert space. To handle disparities between SO3 vs. SU2 space operations, we propose a darkness bit and a Hermite-inspired shape. A simulation of HG modes let us align distinct shapes to quantum optical states. Three examples of applications show our color sphere in practice. First, we apply the Hilbert-Color mapping in Polarization. Then, the same color-space is shown in Orbital Angular Momentum. We also represent location paths in this color-mapping. The simulations and practical comparisons let us refine the proposed color sphere convention. For higher-order and path-to-industry, any sphere section serves as color constellation diagram. One color-space sphere served as common ground to represent coexisting concepts among diverse physical areas. The introduced change diagrams are visual tools to communicate setups and operators. The examples showed a unique notation matches many physical processes. The resulting diagram of superposition of spatially separated optical paths is coherent with a Plate on Polarization or cylinder lens on OAM Hermite Gaussian modes. A unique change diagram describes the three examples. The meaning persist despite the physical implementation. Found also how this color space let us grasp visually some meaning. Thus, the amount of blue in a state representation indicated the degree of its phase shift. Overall, we presented math and visual tools to display and compare experiments. We showed examples in different physical modes, all linked to a unique color sphere.