Electromagnetically induced transparency (EIT) and EIT-like effects have been investigated in a wide variety of coupled resonant systems. Here, a classification of the phase characteristics of the EIT-like spectral responses is presented. Newly identified phase responses reveal unexplored operation regimes of EIT-like systems. Taking advantage of these new phase regimes, one can obtain group delay, dispersion and nonlinearity properties greatly enhanced by almost one order of magnitude, compared to the traditionally constructed EIT-like devices, all of which breaks the fundamental limitation (e.g. delay–bandwidth product) intrinsic to atomic EIT and EIT-like effects. Optical devices and electrical circuits are analyzed as examples showing the universality of our finding. We show that cavity quantum electrodynamics (QED)-based quantum phase gates can be greatly improved to achieve a phase shift of π . The new phase characteristics are also believed to be useful to build novel doubly resonant devices in quantum information based cavity QED, optomechanics and metamaterials.
Electromagnetically induced transparency (EIT) and EIT-like effects have been investigated in a wide variety of coupled resonant systems. Here, a classification of the phase characteristics of the EIT-like spectral responses is presented. Newly identified phase responses reveal unexplored operation regimes of EIT-like systems. Taking advantage of these new phase regimes, one can obtain group delay, dispersion and nonlinearity properties greatly enhanced by almost one order of magnitude, compared to the traditionally constructed EIT-like devices, all of which breaks the fundamental limitation (e.g. delay–bandwidth product) intrinsic to atomic EIT and EIT-like effects. Optical devices and electrical circuits are analyzed as examples showing the universality of our finding. We show that cavity quantum electrodynamics (QED)-based quantum phase gates can be greatly improved to achieve a phase shift of π . The new phase characteristics are also believed to be useful to build novel doubly resonant devices in quantum information based cavity QED, optomechanics and metamaterials.
Coupled microresonators exhibit great potential for nonlinear applications. In the present work, we explore the nonlinear performance of an embedded ring resonator analogous to an electromagnetically induced transparency (EIT) medium, also known as coupled resonator induced transparency (CRIT). Interestingly, an EIT-like amplitude response can have a remarkably different power enhancement factor that varies by more than one order of magnitude, which is attributed to the different phase regimes of the embedded micro-ring resonators. In addition to the non-monotonic phase profile reported in atomic EIT systems, the phase responses featuring 2 π and 4 π monotonic transitions are identified and analyzed. We also present an interesting phenomenon, in which the power enhancement changes greatly, even with the same transfer function (both intensity and phase responses). This reveals that wisely choosing the operating regime is critical to optimize nonlinear performance of the embedded double resonator system, without adding to design or fabrication difficulty.
As one of the typical quantum coherence phenomena, electromagnetically induced transparency (EIT) has been extensively applied to implement various quantum coherent manipulations, typically, e.g., optical quantum memories, photonic switches, and optical quantum computations, etc. By applying the input-output theory to the photonic transports through two cavities dispersively coupled by an artificial two-level atomic ensemble, we show here that the EIT-like effects could be observed. Particularly, the transparency windows and phase shift spectra of the transmitting photons could be engineered by manipulating the atomic levels in the ensemble to adjust the effective coupling strength between the cavities. As a consequence, the group delays of the transmitting photons can be manipulated by using the EIT-like effects. The proposal is demonstrated specifically with the experimental superconducting coplanar waveguide resonators coupled by the voltage-biased electrons on liquid Helium.
We provide a broad outline of the requirements that should be met by components produced for a Quantum Information Technology (QIT) industry, and we identify electromagnetically induced transparency (EIT) as potentially key enabling science toward the goal of providing widely available few-qubit quantum information processing within the next decade. As a concrete example, we build on earlier work and discuss the implementation of a two-photon controlled phase gate (and, briefly, a one-photon phase gate) using the approximate Kerr nonlinearity provided by EIT. In this paper, we rigorously analyze the dependence of the performance of these gates on atomic dephasing and field detuning and intensity, and we calculate the optimum parameters needed to apply a π phase shift in a gate of a given fidelity. Although high-fidelity gate operation will be difficult to achieve with realistic system dephasing rates, the moderate fidelities that we believe will be needed for few-qubit QIT seem much more obtainable.
Abstract Electromagnetically induced transparency (EIT) stems from a quantum system, where an opaque atomic medium appears the narrow transparent state within a wide absorption area. This phenomenon can be achieved by quantum interference of pumping light and detecting light at different energy levels of transitions. In the generation process of EIT effect, in addition to transparent state, the atomic medium is usually accompanied with a strong dispersion effect, which will bright about a significant reduction of light velocity, thus realizing many important applications, such as slow light propagations. Although the EIT effect has many important applications, its application scenarios are greatly limited due to the fact that EIT realization usually requires specific and complicated conditions, such as refrigeration temperature, high intensity laser, etc. Recently, the analogue of EIT effect in metamaterial has attracted increasing attentions due to its advantages such as controllable room temperature and large operating bandwidth. Metamaterial analogue of EIT effect has become a new research focus. In this article, we review current research progresses on EIT metamaterials. Firstly, we describe the theoretical models for analyzing EIT metamaterials, including the mechanical oscillator model and the equivalent circuit model. Then, we describe the simulations, designs and experiments of passive EIT metamaterials with fixed structures and active EIT metamaterials with tunable elements. Furthermore, the applications of EIT metamaterials in the areas of slow lights, sensings, absorptions and other fields are also reviewed. Finally, the possible directions and key issues of future EIT metamaterial researches are prospected.
We provide a broad outline of the requirements that should be met by components produced for a Quantum Information Technology (QIT) industry, and we identify electromagnetically induced transparency (EIT) as potentially key enabling science toward the goal of providing widely available few-qubit quantum information processing within the next decade. As a concrete example, we build on earlier work and discuss the implementation of a two-photon controlled phase gate and a one-photon phase gate using the approximate Kerr nonlinearity provided by EIT. We rigorously the dependence of the performance of these gates on atomic dephasing and field detuning and intensity, and we calculate the optimum parameters needed to apply a pi phase shift in a gate of a given fidelity. Although high-fidelity gate operation will be difficult to achieve with realistic system dephasing rates, the moderate fidelities that we believe will be needed for few-qubit QIT seem much more obtainable.
Recently, metamaterials with unique electromagnetic (EM) properties have attracted people’s great interest. In metamaterials, the eclectic and magnetic response to incident light can be conveniently tuned. For example, the enhancement of electric and magnetic response can bring about effective negative permittivity (epsilon) and negative permeability (mu), respectively [1,2]. Since the interactions of metamaterials and light can be manipulated by varying the structural and geometric parameters of metamaterials, metamaterials provide us a convenient platform to mimic a variety of quantum-optic phenomena such as electromagnetically induced transparency (EIT) [3] and vacuum Rabi splitting [4]. EIT in quantum optics occurs when atoms can transit via two pathways and make a destructive interference to inhibit absorption, which brings about slow-wave effect and strong group velocity dispersion [5]. However, the building process of atomic EIT is still unclear due to the very quick time evolution in the transition. EIT analog in metamaterials realized by the interference in two classical pathways can observe the dynamic process during the establishment of EIT in the time scale much larger than the atomic counterpart. Based on a waveguide structure, we study the dynamic evolution of EIT in metamaterials and reveal experimentally the parameters controlling excitation transfer during the building process of EIT [6]. The dynamic properties of classical EIT not only mimic the population transfer between energy levels in the atomic EIT, but also present a physical picture of rapid optical response that plays an important role in fast manipulating light by EIT. Moreover, we study another important problem in classical EIT, i.e., the influence of intrinsic losses on EIT. We provide systematic experimental demonstration of EIT in metamaterials with tunable intrinsic loss. It is found under the EIT condition the maximum transmittance as well as the corresponding group delay in the transmission window is nearly unchanged and only the delay bandwidth is affected by the intrinsic loss. Vacuum Rabi splitting, which appears when atoms or atom-like systems are put inside a cavity, is another important quantum phenomenon that may be applied for the quantum entanglement and computations [7]. In a cavity with high quality factor and small volume, vacuum Rabi splitting can occur for a single atom in the strong coupling regime. In general, the cavity modes are all in the form of standing waves and the cavity fields are inhomogeneous. To ensure strong coupling of an atom (or a quantum dot) and photons, we need to place the atom right at the peak(s) of the fields, which is very challenging in atomic or solid-state experiments. Moreover, in atomic experiments, a cold atom is needed. This is because a hot atom can move around the position-variant fields under thermal fluctuation, making the coupling of the atom and the cavity unstable. To overcome the position uncertainty, we propose another type of cavity filled with zero-index metamaterials (ZIMs) in which epsilon=0 and/or mu=0 . In an impedance-matched ZIM ( epsilon=mu=0), both phases and amplitudes of the EM fields are homogeneous [8]. However, in a epsilon-near-zero (ENZ) medium (epsilon=0,mu=1), although the phases of EM waves are uniform, in most cases the amplitudes of electric fields will vary in space. In practice, a highly doped semiconductor such as InGaAs can be utilized as an ENZ medium [9] and self-assembled or colloidal quantum dots could be embedded in this ENZ medium. So how to realize uniform electric fields in an ENZ medium is an important practical problem. We discover that, when an ENZ medium is inserted in the center of a two-dimensional photonic crystal with a gap that plays a role of magnetic wall, the electric fields in the ENZ medium are forced to be nearly uniform, as required by Maxwell equations and boundary conditions. Then, we embed a quantum dot in the ENZ medium confined by the magnetic-wall-like photonic barrier and obtain a nearly position-independent Rabi-like splitting. This is because the enhanced electric fields are almost same at any place of the ENZ medium. Finally, by loading lumped capacitors and inductors in a microwave transmission line, we realize a cavity with effective ZIM in which the enhanced fields are nearly homogeneous [10]. When an atom-like split ring resonator is coupled to this effective ZIM at various locations, we observe the nearly position-independent Rabi-like splitting. A ZIM-filled cavity in the strong coupling regime will provide us a new platform to study the interactions of atoms and photons in the future.