Progress in Quantum Electronics最新文献

The minimalistic design of InGaN-based MQW microdisk lasers based on whispering gallery mode (WGM) resonances has been attracting research interests in recent years. To compete with the prevalent InGaN-based VCSELs and edge-emitters, microdisk lasers must demonstrate superior performance under electrical injection. Yet, the challenges in the shift from initial optically pumped investigations to studies centered on electrically injected microdisk lasers has posed a barrier to successful commercialization.

Probing the optical and charge transport characteristics in molecular junctions not only provides fundamental understanding of light–matter interactions and quantum transport at the atomic and molecular scale, but also holds great promise for the development of molecular-scale optical and electronic devices. Herein, an overview of recent progress in fabricating and characterizing photoswitching molecular systems using both the current measured from single molecule circuits as well as the light signals monitored in photodetectors is presented. We review four groups of azobenzene, diarylethene, dihydroazulene, spiropyran photoswitching molecules that have been used to construct photoswitching molecular devices by scanning tunneling microscope-based or mechanically controlled break-junction techniques, focusing on the impact of light-induced reactions on the charge transport processes at the single molecule level. We also discuss key optical properties of photoswitching systems, uncovered by a range of optical methods including transient absorption and ultrafast spectroscopies, that are critically related to structural symmetry or nonlinear optical effects.

Advanced laser methods have recently been used in human and animal head tissues for functional and molecular imaging. Combining these approaches with various probes and nanostructures gives up a new path for theranostic applications in brain tissues. The diverse optical properties of head tissues such as the scalp, skull, cerebrospinal fluid, and brain tissues result in considerable photon scattering and absorption. Diffusion of photons inside head tissues decreases the optical imaging quality and limits the optical resolutions of cellular and neural treatments. Tissue optical clearing (TOC) was set up more than a century ago to make tissue transparent by immersing it in liquids with a matching RI as the tissue. This approach has lately gained popularity in the field of brain imaging. The physical fundamentals of optical clearing (OC) procedures for brain tissue, such as RI matching with chemical agents, dehydration, delipidation, decalcification, hyperhydration, and innovative hybrid brain OC methods, are explored here. This study covers critical issues such as choosing the best brain OC methods and optimizing wavelength and laser energy to control tissue optical properties. Here, innovative ways for decreasing photon scattering based on immersion procedures and induced heating tunnels are discussed. In addition, simulation methods of photon migration in brain tissues (based on random approaches) are investigated, paving the way for the proper brain OC strategy. Finally, the limitations of this method for in vivo applications are discussed, as well as possible applications in cranial implants, optogenetics, laser brain stimulation, and functional optical imaging.

Miniaturized and rationally assembled nanostructures exhibit extraordinarily distinct physical properties beyond their individual units. This review will focus on structured small-scale optical cavities, especially on plasmonic nanoparticle lattices that show unique electromagnetic near fields from collective optical coupling. By harnessing different material systems and structural designs, various light-matter interactions can be engineered, such as nanoscale lasing, nonlinear optics, and exciton-polariton coupling. Key device performance of nanoscale lasers will be discussed, including low power threshold, output tunability, and electrical pump. This review will also cover emerging applications of nanoscale optical cavities in quantum engineering. Structured nanoscale cavities can serve as a scalable platform for integrated photonic circuits and hybrid quantum photonic systems.

Quantum sensing, built upon fundamental quantum phenomena like entanglement and squeezing, is revolutionizing precision and sensitivity across diverse domains, including quantum metrology and imaging. Its impact is now stretching into radar and LiDAR applications, giving rise to the concept of quantum radar. Unlike traditional radar systems relying on classical electromagnetic, quantum radar harnesses the potential of the quantum properties of photon states like entanglement and quantum superposition to transcend established boundaries in sensitivity and accuracy. This comprehensive review embarks on an exploration of quantum radar and quantum LiDAR, guided by two primary objectives: enhancing sensitivity through quantum resources and refining accuracy in target detection and range estimation through quantum techniques. We initiate our exploration with a thorough analysis of the fundamental principles of quantum radar, which includes an evaluation of quantum illumination protocols, receiver designs, and their associated methodologies. This investigation spans across both microwave and optical domains, providing us with insights into various experimental demonstrations and the existing technological limitations. Additionally, we review the applications of quantum radar protocols for enhanced accuracy in target range determination and estimation. This section of our review involves a comprehensive analysis of quantum illumination, quantum interferometry radar, and other quantum radar protocols, providing insights into their contributions to the field. This review offers valuable insights into the current state of quantum radar, providing a deep understanding of key concepts, experiments, and the evolving landscape of this dynamic and promising field.

Encoding quantum information into a set of harmonic oscillators is considered a hardware efficient approach to mitigate noise for reliable quantum information processing. Various codes have been proposed to encode a qubit into an oscillator – including cat codes, binomial codes and Gottesman–Kitaev–Preskill (GKP) codes – and are among the first to reach a break-even point for quantum error correction. Though GKP codes are widely recognized for their promise in quantum computation, they also facilitate near-optimal quantum communication rates in bosonic channels and offer the ability to safeguard arbitrary quantum states of oscillators. This review focuses on the basic working mechanism, performance characterization, and the many applications of GKP codes—emphasizing recent experimental progress in superconducting circuit architectures and theoretical advancements in multimode GKP qubit codes and oscillators-to-oscillators (O2O) codes. We begin with a preliminary continuous-variable formalism needed for bosonic codes. We then proceed to the quantum engineering involved to physically realize GKP states. We take a deep dive into GKP stabilization and preparation in superconducting architectures and examine proposals for realizing GKP states in the optical domain (along with a concise review of GKP realization in trapped-ion platforms). Finally, we present multimode GKP qubits and GKP-O2O codes, examine code performance and discuss applications of GKP codes in quantum information processing tasks such as computing, communication, and sensing.

Mechanical systems prepared in quantum non-Gaussian states constitute a new advanced class of phenomena breaking the laws of classical physics. Specifically, such mechanical states cannot be described as any mixture of the Gaussian states produced by operations described by Hamiltonians at most quadratic in position and momentum, such as phase rotations, squeezing operations and linear driving. Therefore, they form a class of resourceful states for quantum technological tasks such as metrology, sensing, simulation and computation. Quantum opto- and electromechanics are advanced platforms for quantum mechanical experiments with broad applications offering various methods for preparing such mechanical quantum non-Gaussian states. The suitability of these platforms as transducers additionally allows the integration of such mechanical states into a variety of other related platforms. Here, we summarize the current techniques for creating these states, emphasizing those that have had experimental success and looking to methods that show promise for future experiments. By collating these results, we expect to stimulate new ideas for non-Gaussian state preparation in these fields, resulting in the realization of further experiments. Moreover, we provide concise and clear explanations of the milestones of research in the quantum non-Gaussianity of mechanical states and its implementation and verification in a laboratory setting.

Two-dimensional (2D) magnetism in van der Waals (vdW) atomic crystals and moiré superlattices has emerged as a topic of tremendous interest in the fields of condensed matter physics and materials science within the past half-decade since its first experimental discovery in 2016–2017. It has not only served as a powerful platform for investigating phase transitions in the 2D limit and exploring new phases of matter, but also provided new opportunities for applications in microelectronics, spintronics, magnonics, optomagnetics, and so on. Despite the flourish developments in 2D magnetism over this short period of time, further efforts are welcome in multiple forefronts of 2D magnetism research for achieving the ultimate goal of routinely implementing 2D magnets as quantum electronic components. In this review article, we will start with basic concepts and properties of 2D magnetism, followed by a brief overview of historical efforts in 2D magnetism research and then a comprehensive review of vdW material-based 2D magnetism. We will conclude with discussions on potential future research directions for this growing field of 2D vdW magnetism.