Strong Light–Matter Coupling as a New Tool for Molecular and Material Engineering: Quantum Approach

Abstract

When atoms come together and bond, these new states are called molecules and their properties determine many aspects of our daily life. Strangely enough, it is conceivable for light and molecules to bond, creating new hybrid light–matter states with far‐reaching consequences for these strongly coupled materials. Even stranger, there is no “real” light needed to obtain the effects; it simply appears from the vacuum, creating “something from nothing.” Surprisingly, the setup required to create these materials has become moderately straightforward. In its simplest form, one only needs to put a strongly absorbing material at the appropriate place between two mirrors, and quantum magic can appear. Only recently has it been discovered that strong coupling can affect a host of significant effects at a material and molecular level, which were thought to be independent of the “light” environment: phase transitions, conductivity, chemical reactions, etc. This review addresses the fundamentals of this opportunity: the quantum mechanical foundations, the relevant plasmonic and photonic structures, and a description of the various applications, connecting material chemistry with quantum information, entanglement, nonlinear optics, and chemical reactivity. Ultimately, revealing the interplay between light and matter in this new regime opens attractive avenues for various new technologies.

Recent Advances in Quantum Effects of 2D Materials

“…For example, according to the theory of cavity quantum electrodynamics (CQED), when the coupling strength between a quantum emitter and a cavity is greater than both the decays of emitter and cavity, the system reaches strong coupling region, characterizing as Rabi splitting and Rabi oscillation in the frequency and time domain, respectively (Figure b) . The strong coupling system is a typical coherent coupling system which can sustain coherent states with long de‐coherent time that allows advanced quantum technologies such as constructing quantum network and controllable quantum manipulations, greatly benefiting quantum communication and computing . Constructing a strong coupling system requires the quantum emitter with large transition momentum, which perfectly matches the advantage of strong excitonic effect in 2DLMs .…”

“…[194,195] The strong coupling system is a typical coherent coupling system which can sustain coherent states with long de-coherent time that allows advanced quantum technologies such as constructing quantum network and controllable quantum manipulations, greatly benefiting quantum communication and computing. [194][195][196][197][198][199][200] Constructing a strong coupling system requires the quantum emitter with large transition momentum, which perfectly matches the advantage of strong excitonic effect in 2DLMs. [201,202] Therefore, with the employment of 2DLMs, numbers of investigations with novel observations in the field of strong coupling are performed.…”

Tunable Open‐Access Microcavities for Solid‐State Quantum Photonics and Polaritonics

“…Here (m, n) are named the transverse mode orders, indicating that HG modes specified by the same value of (m + n) are degenerate. For the fundamental mode specified by m = n = 0, Equations (7) and (8) reduce to Equations (2) and (6), describing a Gaussian distribution of optical field in the transverse plane. If we solve the paraxial wave equation in cylindrical coordinates with the transform r = x 2 + y 2 , r (cos ϕ sin ϕ) = (x y),…”

“…[2,3] Otherwise, the system stays in the weak coupling regime in which the emitter and cavity lifetimes are modified by each other, resulting in cavity-enhanced or cavity-prohibited spontaneous emission, known as the Purcell effect. [4,5] Microcavities play a significant role in a wide range of research areas including light-matter interaction, [2] nonlinear optics, [6] quantum information, [7] and topological photonics, [8,9] serving as crucial elements of on-chip microlasers, [10] optical switches, [11] isolators, [12,13] sensors, [14] photonic logic gates, [15] quantum simulators, [16,17] and high-efficiency quantum light sources. [18] The main advantage of the microcavities over the macroscopic cavities is the small mode volume that is a necessity for enhancing light-matter interaction.…”

Linear and nonlinear optical effects in biophotonic structures using classical and nonclassical light

“…Since the first development of quantum physics, the entanglement is considered to be "the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought" [91,92]. This assessment was later confirmed by Bell's theorem [93] and the subsequent experiments, establishing that quantum entanglement gives rise to a certain kind of nonlocality in nature.…”