An attractive feature of surface plasmons (SPs) is the sub-wavelength characteristics, especially the SPs in two dimensional Dirac systems. In mid-infrared region, the wave vectors of graphene plasmons (GPs) can be two orders larger than that in vacuum, which have potential applications in optical imaging. Here, we propose a scheme that combining the GPs and structured illumination microscopy to realize a nanometer-scale microscopy. This scheme also takes advantage of the other two exciting properties of GPs, <i>i.e.</i>, tunability and low loss. The microscopy works in the linear regime and can be used in bioimaging.
For the first time, we show how quantum teleportation can be achieved without the assistance of classical channels. Our protocol does not need any pre-established entangled photon pairs beforehand. Just by utilizing quantum Zeno effect and couterfactual communication idea, we can achieve two goals; entangling a photon and an atom and also disentangling them by non-local interaction. Information is completely transferred from atom to photon with controllable disentanglement processes. More importantly, there is no need to confirm teleportation results via classical channels.
The resolutions of the optical lithography is limited by the well-known Rayleigh limit. Although the atom lithography can generate features smaller than this limit, the spacing of the pattern is still limited by the optical wavelength. Here, we proposed two atom lithography methods, both of which used the coherent Rabi oscillation to break the diffraction limit. One is in the microwave regime where the Rydberg atom is used and micrometer resolution can be achieved. The other is in the optical regime where sub-10 nanometer resolution is possible.
Quantum entanglement is a critical resource for quantum information and quantum computation. However, entanglement of a quantum system is subjected to change due to the interaction with the environment. One typical result of the interaction is the amplitude damping that usually results in the reduction of the entanglement. Here we propose a protocol to protect quantum entanglement from the amplitude damping by applying Hadamard and CNOT gates. As opposed to some recently studied methods, the scheme presented here does not require weak measurement in the reversal process, leading to a faster recovery of entanglement. We propose a possible experimental implementation based on linear optical system.
Controlling reflectivity optically over a wide range of frequency band can be of great demand technologically.
In this paper we show how this can be realized using a Fabry-P´erot cavity filled with a three-level atomic gas.
Furthermore, we employ both concepts of electromagnetic induced transparency EIT and the white light cavity
which in turn play the essential rule to control the susceptibility of the atomic gas. Once the susceptibility is
controlled, all one needs to do is to look for the satisfying resonance conditions that run over a wide range of
frequencies, which results in a wide band optical switch.
The resolutions of the optical microscope and the optical lithography are both limited by the well-known Rayleigh
limit. Rabi oscillation is a coherent nonlinear process that can modulate the population distribution between
two energy states and also modulate the resonant fluorescence spectrum. If we have a gradient electric field
amplitude in the space, the Rabi frequency for different position is also different. The spatial distribution of the
population in the excited state can be modulated and the spatial information of the atoms can also be encoded
in the resonant fluorescence spectrum. If the gradient of the field is large enough, the pattern generated can be
subwavlength and the atoms with subwavelength distances can also be extracted. Here we present a review on
both the subwavelength photolithography and microscopy via Rabi oscillations.
The properties of localised dipole emitters in the form of a quantum dot or a colour centre embedded in a crystal
environment can be drastically modified by a change in the composition, size and shape of the environment in
which the emitter is embedded. Thanks to recent advances in material deposition techniques and lithography,
as well as the advances in detection techniques and optical manipulation, experimental work is now capable of
revealing a new range of physical phenomena when the typical dimensions are of the order of an optical dipole
transition wavelength and below. These advances have arisen at a time of a heightened research effort devoted to
the important goal of identifying a qubit and a suitable environment that forms the basis for a scalable hardware
architecture for the practical realisation of quantum information processing. A physical system that we have
recently put forward as a candidate for such a purpose involves localised emitters in the form of quantum dots
or colour centres embedded in a nanocrystal. This suggestion became more persuasive following the success of
experiments which, for the first time, were able to demonstrate quantum cryptography using a nitrogen vacancy
in a diamond nanocrystal as a single-photon source. It has, however, been realised that a more versatile scenario
could be achieved by making use of the interplay between dielectric cavity confinement and dipole orientation.
Besides position dependence the main properties exhibit strong dipole orientational dependece suggesting that the
system is a possible candidate as a qubit for a scalable hardward architecture for quantum information processing.
Cavity confinement can control processes since it can lead to the enhancement and the complete suppression of
the de-excitation process, with further control provided by the manipulation of the dipole orientation by optical
means. This article is concerned with the modelling of quantum processes for quantum systems localised in
artificially fabricated structures made of high conductivity metals and dielectric cavities. The essential features
of cavity field confinement in this context are presented and the effects on de-excitation rates are assessed.
Theoretical work has already established the existence of a light-induced torque acting on the centre of mass of an atom, ion or molecule immersed in twisted light, where the transition frequency is suitably detuned from that of the twisted light beam. The twisted beam carries <i>l</i> units of orbital angular momentum per photon, and the steady-state saturation form of the torque is also determined by the width of the upper state in the atomic transition. It has been shown that, to leading order, the transfer of orbital angular momentum can only occur between the twisted light and the centre of mass motion. We argue here that, for small linewidth, the full time-dependence of the torque is needed to account correctly for the dynamics of atoms in a twisted light beam. We outline the theoretical framework needed to derive this full time-dependence, applying the theory to the motion in a twisted light beam of Eu<sup>3+</sup> ions, which possess a particularly narrow linewidth state. For relatively large linewidth, the steady-state forces and torque are appropriate, but the processes of cooling and trapping require the application of several suitably oriented twisted beams. The description of atomic motion in multiple twisted beams demands the application of special coordinate transformations. We show how to construct the appropriate transformation matrices to represent a twisted light beam propagating in an arbitrary direction, and we proceed to investigate the cooling and trapping of Mg<sup>+</sup> ions in sets of pairs of counter-propagating twisted beams in two-dimensional and three-dimensional molasses configurations.