Multiphoton controllable transport between remote resonators

We develop a novel method for multiphoton controllable transport between remote resonators. Specifically, an auxiliary resonator is used to control the coherent long-range coupling of two spatially separated resonators, mediated by a coupled-resonator chain of arbitrary length. In this manner, an arbitrary multiphoton quantum state can be either transmitted through or reflected off the intermediate chain on demand, with very high fidelity. We find, on using a time-independent perturbative treatment, that quantum information leakage of an arbitrary Fock state is limited by two upper bounds, one for the transmitted case and the other for the reflected case. In principle, the two upper bounds can be made arbitrarily small, which is confirmed by numerical simulations.Comment: 16 pages, 7 figure

Roadmap on quantum nanotechnologies

Quantum phenomena are typically observable at length and time scales smaller than those of our everyday experience, often involving individual particles or excitations. The past few decades have seen a revolution in the ability to structure matter at the nanoscale, and experiments at the single particle level have become commonplace. This has opened wide new avenues for exploring and harnessing quantum mechanical effects in condensed matter. These quantum phenomena, in turn, have the potential to revolutionize the way we communicate, compute and probe the nanoscale world. Here, we review developments in key areas of quantum research in light of the nanotechnologies that enable them, with a view to what the future holds. Materials and devices with nanoscale features are used for quantum metrology and sensing, as building blocks for quantum computing, and as sources and detectors for quantum communication. They enable explorations of quantum behaviour and unconventional states in nano- and opto-mechanical systems, low-dimensional systems, molecular devices, nano-plasmonics, quantum electrodynamics, scanning tunnelling microscopy, and more. This rapidly expanding intersection of nanotechnology and quantum science/technology is mutually beneficial to both fields, laying claim to some of the most exciting scientific leaps of the last decade, with more on the horizon

Two-color electromagnetically induced transparency via modulated coupling between a mechanical resonator and a qubit

We discuss level splitting and sideband transitions induced by a modulated coupling between a superconducting quantum circuit and a nanomechanical resonator. First, we show how to achieve an unconventional time-dependent longitudinal coupling between a flux (transmon) qubit and the resonator. Considering a sinusoidal modulation of the coupling strength, we find that a first-order sideband transition can be split into two. Moreover, under the driving of a red-detuned field, we discuss the optical response of the qubit for a resonant probe field. We show that level splitting induced by modulating this longitudinal coupling can enable two-color electromagnetically induced transparency (EIT), in addition to single-color EIT. In contrast to standard predictions of two-color EIT in atomic systems, we apply here only a single drive (control) field. The monochromatic modulation of the coupling strength is equivalent to employing two eigenfrequency-tunable mechanical resonators. Both drive-probe detuning for single-color EIT and the distance between transparent windows for two-color EIT, can be adjusted by tuning the modulation frequency of the coupling.Comment: 13 pages; 8 figure

Ultrafast nonlinear plasmonics

Metal nanostructures can enhance the optical signals by orders of magnitude due to surface plasmon resonance. This field enhancement of the plasmonic nanostructures has led to optical detection and light manipulation beyond the free space diffraction limit. However, the significant enhancement of optical signals of the nanostructures has not been fully understood. In order to examine field-enhanced phenomena, this dissertation studies a variety of plasmonic nanostructures using two nonlinear optical processes, multiphoton-absorption-induced luminescence (MAIL) and metal-enhanced multiphoton absorption polymerization (MEMAP). Nonlinear absorption of near-infrared light can lead to luminescence of metal nanostructures. This luminescence can be observed at localized areas of the nanostructures because of localized surface plasmon resonance and the “lightning rod” nanoantenna effect. In the presence of a prepolymer resin, luminescence generated from the nanostructures can induce polymerization by exciting a photoinitiator. The strong correlation between MAIL and MEMAP is demonstrated by using different excitation wavelengths and different types of prepolymer resins. While localized surface plasmon resonance plays a pivotal role in field-enhanced optical phenomena observed at local areas of gold nanoparticles, nanowires, and nanoplates, surface plasmon propagation is essential to understanding of the nonlinear optical properties in silver nanowires. As silver nanowires can support surface plasmon propagation for many microns, excitation of NIR light at one end of the nanowire can induce luminescence at the other end of the nanowire. This broadband luminescence can excite a photoinitiator, inducing polymerization. The luminescence-induced polymerization in remote positions can be used to assemble nanostructures. Nonlinear luminescence and its correlation to polymerization are also studied using carbon nanostructures. While metal nanostructures exhibit plasmonic field enhancement, carbon nanotubes have strong Coulomb interactions between excited electrons and holes, which results in luminescent emission. Additionally, the high density of electron states of carbon nanotubes can increase the probability of the recombination of the excited electron and hole, which in turn induce luminescence. The luminescence emission and photopolymerization are studied using different kinds of carbon nanostructures

Stabilizing optical microcavities in 3D

Optical (micro-)cavities are the workhorse for studying light-matter interactions with important applications in lasing, sensing, and quantum simulations, to name a few. Open resonators in particular offer great versatility due to their tunability but pose challenges in terms of control. This concerns, on the one hand, the control of their length, and on the other hand, the relative orientation (tilt) of the mirror planes to each other. The latter becomes particularly important when working with optically unstable resonators, such as plane-parallel resonators.There are numerous strategies to enhance stability using passive techniques, such as material selection, mechanical damping, or thermal compensation. But especially for tuneable microcavities often an active stabilization method with feedback control systems must be employed. Here, we present a novel method for tilt measurement and stabilization using inverse solving of the Schrödinger equation arising in the paraxial description of the cavity modes. Our method enables the highly precise determination of absolute tilt angles, making it suitable for microcavity applications that require the highest level of cavity parallelism