Showing papers on "Electromagnetically induced transparency published in 2010"
TL;DR: Electromagnetically induced transparency in an optomechanical system whereby the coupling of a cavity to a light pulse is used to control the transmission of light through the cavity may help to allow the engineering of light storage and routing on an optical chip.
Abstract: Electromagnetically induced transparency is a quantum interference effect observed in atoms and molecules, in which the optical response of an atomic medium is controlled by an electromagnetic field. We demonstrated a form of induced transparency enabled by radiation-pressure coupling of an optical and a mechanical mode. A control optical beam tuned to a sideband transition of a micro-optomechanical system leads to destructive interference for the excitation of an intracavity probe field, inducing a tunable transparency window for the probe beam. Optomechanically induced transparency may be used for slowing and on-chip storage of light pulses via microfabricated optomechanical arrays.
1,316 citations
TL;DR: A planar metamaterial analogue of electromagnetically induced transparency at optical frequencies is experimentally demonstrated and yields a sensitivity of 588 nm/RIU and a figure of merit of 3.8.
Abstract: We experimentally demonstrate a planar metamaterial analogue of electromagnetically induced transparency at optical frequencies. The structure consists of an optically bright dipole antenna and an optically dark quadrupole antenna, which are cut-out structures in a thin gold film. A pronounced coupling-induced reflectance peak is observed within a broad resonance spectrum. A metamaterial sensor based on these coupling effects is experimentally demonstrated and yields a sensitivity of 588 nm/RIU and a figure of merit of 3.8.
1,130 citations
TL;DR: In this paper, the authors consider the dynamical behavior of a nanomechanical mirror in a high-quality cavity under the action of a coupling laser and a probe laser and demonstrate the existence of the analog of electromagnetically induced transparency (EIT) in the output field at the probe frequency.
Abstract: We consider the dynamical behavior of a nanomechanical mirror in a high-quality cavity under the action of a coupling laser and a probe laser. We demonstrate the existence of the analog of electromagnetically induced transparency (EIT) in the output field at the probe frequency. Our calculations show explicitly the origin of EIT-like dips as well as the characteristic changes in dispersion from anomalous to normal in the range where EIT dips occur. Remarkably the pump-probe response for the optomechanical system shares all the features of the $\ensuremath{\Lambda}$ system as discovered by Harris and collaborators.
644 citations
TL;DR: By coupling a probe transition to a Rydberg state using electromagnetically induced transparency (EIT), the strong dipole-dipole interactions onto an optical field are mapped and the resulting cooperative optical nonlinearity is characterized as a function of probe strength and density.
Abstract: By coupling a probe transition to a Rydberg state using electromagnetically induced transparency (EIT) we map the strong dipole-dipole interactions onto an optical field. We characterize the resulting cooperative optical nonlinearity as a function of probe strength and density. We demonstrate good quantitative agreement between the experiment and an $N$-atom cooperative model for $N=3$ atoms per blockade sphere and the $n=60$ Rydberg state. The measured linewidth of the EIT resonance places an upper limit on the dephasing rate of the blockade spheres of $l110\text{ }\text{ }\mathrm{kHz}$.
413 citations
TL;DR: The observed almost 100% modulation of the reflection and transmission of propagating microwaves demonstrates full controllability of individual artificial atoms and a possibility to manipulate the atomic states.
Abstract: We present experimental observation of electromagnetically induced transparency (EIT) on a single macroscopic artificial "atom" (superconducting quantum system) coupled to open 1D space of a transmission line. Unlike in an optical media with many atoms, the single-atom EIT in 1D space is revealed in suppression of reflection of electromagnetic waves, rather than absorption. The observed almost 100% modulation of the reflection and transmission of propagating microwaves demonstrates full controllability of individual artificial atoms and a possibility to manipulate the atomic states. The system can be used as a switchable mirror of microwaves and opens a good perspective for its applications in photonic quantum information processing and other fields.
305 citations
TL;DR: This work demonstrates EIT with a single atom quasi-permanently trapped inside a high-finesse optical cavity, where the atom acts as a quantum-optical transistor with the ability to coherently control the transmission of light through the cavity.
Abstract: Optical nonlinearities offer unique possibilities for the control of light with light. A prominent example is electromagnetically induced transparency (EIT), where the transmission of a probe beam through an optically dense medium is manipulated by means of a control beam. Scaling such experiments into the quantum domain with one (or just a few) particles of light and matter will allow for the implementation of quantum computing protocols with atoms and photons, or the realization of strongly interacting photon gases exhibiting quantum phase transitions of light. Reaching these aims is challenging and requires an enhanced matter-light interaction, as provided by cavity quantum electrodynamics. Here we demonstrate EIT with a single atom quasi-permanently trapped inside a high-finesse optical cavity. The atom acts as a quantum-optical transistor with the ability to coherently control the transmission of light through the cavity. We investigate the scaling of EIT when the atom number is increased one-by-one. The measured spectra are in excellent agreement with a theoretical model. Merging EIT with cavity quantum electrodynamics and single quanta of matter is likely to become the cornerstone for novel applications, such as dynamic control of the photon statistics of propagating light fields or the engineering of Fock state superpositions of flying light pulses.
256 citations
TL;DR: In this paper, the authors studied the optical control of mechanical motion within two different nanocavity structures, a zipper nanobeam photonic crystal cavity and a double-microdisk whispering gallery resonator.
Abstract: The combination of the large per-photon optical force and small motional mass achievable in nanocavity optomechanical systems results in strong dynamical back-action between mechanical motion and the cavity light field. In this Article, we study the optical control of mechanical motion within two different nanocavity structures, a zipper nanobeam photonic crystal cavity and a double-microdisk whispering-gallery resonator. The strong optical gradient force within these cavities is shown to introduce significant optical rigidity into the structure, with the dressed mechanical states renormalized into optically bright and optically dark modes of motion. With the addition of internal mechanical coupling between mechanical modes, a form of optically controlled mechanical transparency is demonstrated in analogy to electromagnetically induced transparency of three-level atomic media. Based upon these measurements, a proposal for coherently transferring radio-frequency/microwave signals between the optical field and a long-lived dark mechanical state is described.
235 citations
TL;DR: In this paper, the gain-assisted plasmonic analog of electromagnetically induced transparency (EIT) in a metallic metamaterial was investigated for the purpose to enhance the sensing performance of the EIT-like PLASmonic structure.
Abstract: The gain-assisted plasmonic analog of electromagnetically induced transparency (EIT) in a metallic metamaterial is investigated for the purpose to enhance the sensing performance of the EIT-like plasmonic structure. The structure is composed of three bars in one unit, two of which are parallel to each other (dark quadrupolar element) but perpendicular to the third bar (bright dipolar element), The results show that, in addition to the high sensitivity to the refractive-index fluctuation of the surrounding medium, the figure of merit for such active EIT-like metamaterials can be greatly enhanced, which is attributed to the amplified narrow transparency peak.
223 citations
TL;DR: This work investigates the near-field optical coupling between a single semiconductor nanocrystal (quantum dot) and a nanometer-scale plasmonic metal resonator using rigorous electrodynamic simulations, revealing the roles of Fano interference and hybridization.
Abstract: We investigate the near-field optical coupling between a single semiconductor nanocrystal (quantum dot) and a nanometer-scale plasmonic metal resonator using rigorous electrodynamic simulations. Our calculations show that the quantum dot produces a dip in both the extinction and scattering spectra of the surface-plasmon resonator, with a particularly strong change for the scattering spectrum. A phenomenological coupled-oscillator model is used to fit the calculation results and provide physical insight, revealing the roles of Fano interference and hybridization. The results indicate that it is possible to achieve nearly complete transparency as well as enter the strong-coupling regime for a single quantum dot in the near field of a metal nanostructure.
214 citations
TL;DR: In this article, an approximate analytical solution for a system of two single-photon wave packets interacting via an ideal, localized Kerr medium is presented, along with numerical calculations, for the Schr\"odinger picture.
Abstract: An approximate analytical solution is presented, along with numerical calculations, for a system of two single-photon wave packets interacting via an ideal, localized Kerr medium. It is shown that, because of spontaneous emission into the initially unoccupied temporal modes, the cross-phase-modulation in the Schr\"odinger picture is very small as long as the spectral width of the single-photon pulses is well within the medium's bandwidth. In this limit, the Hamiltonian used can be derived from the ``giant Kerr effect'' for a four-level atom, under conditions of electromagnetically induced transparency; it is shown explicitly that the linear absorption in this system increases as the pulse's spectral width approaches the medium's transparency bandwidth, and hence, as long as the absorption probability remains small, the maximum cross-phase-modulation is limited to essentially useless values. These results are in agreement with the general, causality-based, and unitarity-based arguments of Shapiro and Razavi [J. H. Shapiro, Phys. Rev. A 73, 062305 (2006); J. H. Shapiro and M. Razavi, New J. Phys. 9, 16 (2007)].
182 citations
TL;DR: A planar design of a metamaterial exhibiting electromagnetically induced transparency that is amenable to experimental verification in the microwave frequency band is presented and interpreted in terms of two linearly coupled Lorentzian resonators.
Abstract: We present a planar design of a metamaterial exhibiting electromagnetically induced transparency that is amenable to experimental verification in the microwave frequency band. The design is based on the coupling of a split-ring resonator with a cut-wire in the same plane. We investigate the sensitivity of the parameters of the transmission window on the coupling strength and on the circuit elements of the individual resonators, and we interpret the results in terms of two linearly coupled Lorentzian resonators. Our metamaterial designs combine low losses with the extremely small group velocity associated with the resonant response in the transmission window, rendering them suitable for slow light applications at room temperature.
TL;DR: A planar metamaterial structure composed of a split-ring-resonator (SRR) and paired nano-rods is employed to experimentally realize a spectral response at near-infrared frequencies resembling that of electromagnetically induced transparency.
Abstract: We employ a planar metamaterial structure composed of a split-ring-resonator (SRR) and paired nano-rods to experimentally realize a spectral response at near-infrared frequencies resembling that of electromagnetically induced transparency. A narrow transparency window associated with low loss is produced, and the magnetic field enhancement at the center of the SRR is dramatically changed, due to the interference between the resonances with significantly different linewidths. The variation of the spectral response in terms of relative position of the bright and dark elements is evaluated with numerical simulations.
TL;DR: In this paper, a planar metamaterial exhibiting classical electromagnetically induced transparency (EIT) was used to demonstrate that an EIT-like resonance can be achieved without breaking the symmetry of the structure.
Abstract: We report on our experimental work concerning a planar metamaterial exhibiting classical electromagnetically induced transparency (EIT). Using a structure with two mirrored split-ring resonators as the dark element and a cut wire as the radiative element, we demonstrate that an EIT-like resonance can be achieved without breaking the symmetry of the structure. The mirror symmetry of the metamaterial's structural element results in a selection rule inhibiting magnetic dipole radiation for the dark element, and the increased quality factor leads to low absorption (<10%) and large group index (of the order of 30).
TL;DR: In this article, the trapped magnetic resonance was induced in an asymmetric double-bar structure for electromagnetic waves normally incident onto the double bar plane, which mode otherwise cannot be excited if the double bars are equal in length.
Abstract: We demonstrate that the trapped magnetic resonance mode can be induced in an asymmetric double-bar structure for electromagnetic waves normally incident onto the double-bar plane, which mode otherwise cannot be excited if the double bars are equal in length. By adjusting the structural geometry, the trapped magnetic resonance becomes transparent with little resonance absorption when it happens in the dipolar resonance regime, a phenomenon so-called plasmonic analogue of electromagnetically induced transparency (EIT). This planar EIT-like metamaterial offers a great geometry simplification by combining the radiant and subradiant resonant modes in a single double-bar resonator.
TL;DR: In this paper, the authors explicitly set the threshold of separation between EIT and AT splitting in a unified study of four different three-level atomic systems and compared two resonances.
Abstract: Electromagnetically induced transparency (EIT) and Autler-Townes (AT) splitting are two phenomena that could be featured in a variety of three-level atomic systems. The considered phenomena, EIT and AT, are similar ``looking'' in the sense that they are both characterized by a reduction in absorption of a weak field in the presence of a stronger field. In this paper, we explicitly set the threshold of separation between EIT and AT splitting in a unified study of four different three-level atomic systems. Two resonances are studied and compared in each case. A comparison of the magnitudes of the resonances reveals two coupling-field regimes and two categories of three-level system.
TL;DR: In this article, a whispering-gallery mode optical micro-resonators was used to study the radiation pressure phenomena of radial-breathing modes of optical and mechanical oscillators, and a backaction-imprecision product close to the quantum limit was obtained.
Abstract: Parametric coupling of optical and mechanical degrees of freedom forms the basis of many ultra-sensitive measurements of both force and mechanical displacement. An optical cavity with a mechanically compliant boundary enhances the optomechanical interaction, which gives rise to qualitatively new behavior which can modify the dynamics of the mechanical motion. As early as 1967, in a pioneering work, V. Braginsky analyzed theoretically the role of radiation pressure in the interferometric measurement process, but it has remained experimentally unexplored for many decades. Here, we use whispering-gallery mode optical microresonators to study these radiation pressure phenomena. Optical microresonators simultaneously host optical and mechanical modes, which are systematically analyzed and optimized to feature ultra-low mechanical dissipation, photon storage times exceeding the mechanical oscillation period (i.e. the "resolved-sideband regime") and large optomechanical coupling. In this manner, it is demonstrated for the first time that dynamical backaction can be employed to cool mechanical modes, i.e., to reduce their thermally excited random motion. Utilizing this novel technique together with cryogenic pre-cooling of the mechanical oscillator, the phonon occupation of mechanical radial-breathing modes could be reduced to (n) = 63 +/- 20 excitation quanta. The corresponding displacement fluctuations are monitored interferometrically with a sensitivity at the level of 1.10(-18) m/root Hz, which is below the standard quantum limit (SQL). This implies that the readout is already in principle sufficient to measure the quantum mechanical zero-point position fluctuations of the mechanical mode. Moreover, it is shown that optical measurement techniques employed here are operating in a near-ideal manner according to the principles of quantum measurement, displaying a backaction-imprecision product close to the quantum limit.
TL;DR: In this paper, the authors demonstrate theoretically and numerically that tunable slow light can be realized in planar semiconductor metamaterials with the unit cell composed of two different elements in a broad terahertz regime.
Abstract: We demonstrate theoretically and numerically that tunable slow light can be realized in planar semiconductor metamaterials with the unit cell composed of two different elements in a broad terahertz regime. In the unit cell, one element is a semiconductor split ring resonator and another one is a semiconductor cut wire. The interaction between the two elements of the unit cell, induced directly or indirectly by the incident electromagnetic wave, leads to a transparent window, resembling the classical analog of electromagnetically induced transparency. This transparent window, caused by the coupling of bright-bright modes or dark-bright modes, can be continuously tuned in a broad frequency regime. The strong normal phase dispersion in the vicinity of this transparent window results in the slow light effect. This scheme provides an alternative way to achieve tunable slow light in a broad frequency band and can find important applications in active and reversibly tunable slow light devices.
TL;DR: In this article, a planar planar atomic spectroscopy chip with hot rubidium atoms in hollow-core waveguides was used to demonstrate the ability to reduce the group velocity of light by a factor of 1,200.
Abstract: The ability to slow down the propagation of light touches both fundamental aspects of light–matter interactions and practical applications in photonic communication and computation1,2,3. Optical quantum interference can substantially reduce the speed of light while offering additional dramatic optical effects based on the ability to control electronic quantum states4,5. Recent efforts are increasingly being directed towards harnessing these effects in integrated photonic structures6,7. Here, we report the first demonstration of slow light and electromagnetically induced transparency in a self-contained, planar atomic spectroscopy chip. Using hot rubidium atoms in hollow-core waveguides, we demonstrate 44% optical transparency with a group index of 1,200, or more than sevenfold slower light than in photonic-crystal waveguides8. Optical pulse delays of 16 ns with a delay-bandwidth product of 0.8 are observed. This implementation of atomic quantum state control in integrated photonic structures will enable coherent photonics at ultralow power levels. Researchers exploit atomic quantum state control in a fully integrated photonic atomic spectroscopy chip to reduce the group velocity of light by a factor of 1,200 — the lowest group velocity ever reported for a solid-state material. The findings will enable the creation of on-chip nonlinear optical devices with enhanced quantum coherence operating at ultralow power levels.
TL;DR: In this paper, a planar metamaterial exhibiting classical electromagnetically induced transparency (EIT) was used to demonstrate that an EIT-like resonance can be achieved without breaking the symmetry of the structure.
Abstract: We report on our experimental work concerning a planar metamaterial exhibiting classical electromagnetically induced transparency (EIT). Using a structure with two mirrored split-ring resonators as the dark element and a cut wire as the radiative element, we demonstrate that an EIT-like resonance can be achieved without breaking the symmetry of the structure. The mirror symmetry of the metamaterial's structural element results in a selection rule inhibiting magnetic dipole radiation for the dark element, and the increased quality factor leads to low absorption (<10%) and large group index (of the order of 30).
TL;DR: In this article, the authors demonstrate spatially resolved, coherent excitation of Rydberg atoms on an atom chip using Electromagnetically induced transparency (EIT) to investigate the properties of the atoms near the gold-coated chip surface.
Abstract: We demonstrate spatially resolved, coherent excitation of Rydberg atoms on an atom chip. Electromagnetically induced transparency (EIT) is used to investigate the properties of the Rydberg atoms near the gold-coated chip surface. We measure distance-dependent shifts ({approx}10 MHz) of the Rydberg energy levels caused by a spatially inhomogeneous electric field. The measured field strength and distance dependence is in agreement with a simple model for the electric field produced by a localized patch of Rb adsorbates deposited on the chip surface during experiments. The EIT resonances remain narrow (<4 MHz) and the observed widths are independent of atom-surface distance down to {approx} 20 {mu}m, indicating relatively long lifetime of the Rydberg states. Our results open the way to studies of dipolar physics, collective excitations, quantum metrology, and quantum information processing involving interacting Rydberg excited atoms on atom chips.
TL;DR: A full exploration of the coherent light generation and fluorescence as a function of both pump frequencies reveals that coherent blue light is generated close to (85)Rb two-photon resonances, as predicted by theory, but at high vapor pressure is suppressed in spectral regions that do not support phase matching or exhibit single-Photon Kerr refraction.
Abstract: We demonstrate highly efficient generation of coherent 420 nm light via up-conversion of near-infrared lasers in a hot rubidium vapor cell. By optimizing pump polarizations and frequencies we achieve a single-pass conversion efficiency of 260% per Watt, significantly higher than in previous experiments. A full exploration of the coherent light generation and fluorescence as a function of both pump frequencies reveals that coherent blue light is generated close to (85)Rb two-photon resonances, as predicted by theory, but at high vapor pressure is suppressed in spectral regions that do not support phase matching or exhibit single-photon Kerr refraction. Favorable scaling of our current 1 mW blue beam power with additional pump power is predicted.
TL;DR: In this paper, an atomic phase grating created with arbitrarily weak fields was proposed to allow almost 30% of a probe beam to be diffracted into the first diffraction order.
Abstract: Exploiting the giant Kerr nonlinearity associated with electromagnetically induced transparency, an atomic phase grating created with arbitrarily weak fields is proposed. Almost 30% of a probe beam can be diffracted into the first diffraction order.
TL;DR: In this paper, a superconducting phase qubit was observed to trap coherent population trapping (CPT) by simultaneously driving two coherent transitions in a $\ensuremath{\Lambda}$-type configuration.
Abstract: The phenomenon of coherent population trapping (CPT) of an atom (or solid state ``artificial atom''), and the associated effect of electromagnetically induced transparency (EIT), are clear demonstrations of quantum interference due to coherence in multilevel quantum systems. We report observation of CPT in a superconducting phase qubit by simultaneously driving two coherent transitions in a $\ensuremath{\Lambda}$-type configuration, utilizing the three lowest lying levels of a local minimum of a phase qubit. We observe $60(\ifmmode\pm\else\textpm\fi{}7)%$ suppression of the excited state population under conditions of CPT resonance. We present data and matching theoretical simulations showing the development of CPT in time. Finally, we used the observed time dependence of the excited state population to characterize quantum dephasing times of the system.
TL;DR: It is suggested that the plasmonic EIT is possible to be actively manipulated even by the single optical field, and the mechanical control paves the way for active manipulation of plas Monte Carlo EIT and benefits the clarification of its origin.
Abstract: Plasmonic electromagnetically-induced transparency (EIT) can be excited by a single optical field unlike EIT in atom system, since the coupling between the bright and the dark modes is inherently induced through the near-field interaction in metamaterials. As a result, the complexity of the experimental realization can be reduced significantly, while the tunability is lost inevitably.We suggest a scheme that the plasmonic EIT is possible to be actively manipulated even by the single optical field. The bright and the dark modes are selective to be either coupled or uncoupled, depending on the angle of incidence. Even though the mechanical control has the disadvantage for high-speed applications, it paves the way for active manipulation of plasmonic EIT and benefits the clarification of its origin.
TL;DR: The elementary case of electromagnetically induced transparency with a single atom inside an optical cavity probed by a weak field is experimentally demonstrated and points towards all-optical switching with single photons.
Abstract: We experimentally demonstrate the elementary case of electromagnetically induced transparency with a single atom inside an optical cavity probed by a weak field. We observe the modification of the dispersive and absorptive properties of the atom by changing the frequency of a control light field. Moreover, a strong cooling effect has been observed at two-photon resonance, increasing the storage time of our atoms twenty-fold to about 16 seconds. Our result points towards all-optical switching with single photons.
TL;DR: In this paper, a superconducting two-level system (qubit) dressed by a single-mode cavity field was investigated and it was shown that both the EIT and the EIA can be tuned by controlling the level-spacing of the qubit and hence controlling the dressed system.
Abstract: Electromagnetically induced transparency and absorption (EIT and EIA) are usually demonstrated using three-level atomic systems In contrast to the usual case, we theoretically study the EIT and EIA in an equivalent three-level system: a superconducting two-level system (qubit) dressed by a single-mode cavity field In this equivalent system, we find that both the EIT and the EIA can be tuned by controlling the level-spacing of the superconducting qubit and hence controlling the dressed system This tunability is due to the dressed relaxation and dephasing rates which vary parametrically with the level-spacing of the original qubit and thus affect the transition properties of the dressed qubit and the susceptibility These dressed relaxation and dephasing rates characterize the reaction of the dressed qubit to an incident probe field Using recent experimental data on superconducting qubits (charge, phase, and flux qubits) to demonstrate our approach, we show the possibility of experimentally realizing this proposal
TL;DR: This work investigates the electromagnetic response of the concentric multi-ring, or the bull's eye, structure as an extension of the dual-ring metamaterial which exhibits electromagnetically-induced transparency (EIT)-like transmission characteristics.
Abstract: We investigate the electromagnetic response of the concentric multi-ring, or the bull's eye, structure as an extension of the dual-ring metamaterial which exhibits electromagnetically-induced transparency (EIT)-like transmission characteristics. Our results show that adding inner rings produces additional EIT-like peaks, and widens the metamaterial’s spectral range of operation. Analyses of the dispersion characteristics and induced current distribution further confirmed the peak’s EIT-like nature. Impacts of structural and dielectric parameters are also investigated.
TL;DR: In this article, the principles of the electromagnetically induced transparency (EIT) in basic three-level schemes are sketched, and some applications of this phenomenon are described, and a presentation follows of a five-level EIT model of Bloch equations, which was developed to reconstruct multipeak cascade-EIT spectra registered in a sample of cold 85 Rb atoms in MOT.
Abstract: In the initial part of the paper, the principles of the electromagnetically induced transparency (EIT) in basic three-level schemes are sketched, and some applications of this phenomenon are described. Next a presentation follows of a five-level EIT model of Bloch equations, which was developed to reconstruct multipeak cascade-EIT spectra registered in a sample of cold 85 Rb atoms in MOT. The respective experiment is also described. The achieved good agreement between theory and performed experiment is documented and discussed.
TL;DR: It is shown that controlling relative phases of electromagnetic fields driving an atom with a Δ-configuration energy-level structure enables optical susceptibility to be engineered in novel ways and can yield electromagnetically induced transparency.
Abstract: We show that controlling relative phases of electromagnetic fields driving an atom with a Δ-configuration energy-level structure enables optical susceptibility to be engineered in novel ways. In particular, relative-phase control can yield electromagnetically induced transparency but with the benefit that the transparency window is sandwiched between an absorption and an amplification band rather than between two absorption bands in typical electromagnetically induced transparency. We show that this new phenomenon is achievable for a microwave field interacting with a fluxonium superconducting circuit.
TL;DR: In this article, the authors demonstrate the formation of radio frequency-dressed EIT resonances in a thermal Rb vapour and show that such states exhibit enhanced sensitivity to dc electric fields compared to their bare counterparts.
Abstract: Optical detection of Rydberg states using electromagnetically induced transparency (EIT) enables continuous measurement of electric fields in a confined geometry. In this paper, we demonstrate the formation of radio frequency (rf)-dressed EIT resonances in a thermal Rb vapour and show that such states exhibit enhanced sensitivity to dc electric fields compared to their bare counterparts. Fitting the corresponding EIT profile enables precise measurements of the dc field independent of laser frequency fluctuations. Our results suggest that space charges within the enclosed cell reduce electric field inhomogeneities within the interaction region.