In this paper, we propose module scheme of a quantum commutator for different photonic states based on combining photonic interface and polarization quantum memory. The Q-Commutator ensures the transformation and store of photonic states with reconfigurable time delay, which significantly facilitates the implementation of hybrid quantum networks. The interface module receiving photonic qubits with phase-frequency encoding transmits them to the input of memory module, converting them into polarization encoding. As a memory cell we use a polarization quantum memory consisting of a small number of high-quality WGM ring resonators capable of storing a wideband multi-frequency signal. The proposed configuration has low noise and can be used to build a quantum repeater and distributed sensor systems.
An actual task of quantum communications over long distances is the creation of a bright source of photon pairs operating at standard wavelengths of fiber optic communication lines. In this work, we experimentally investigated the spectral and correlation characteristics of photon pairs generated on the phenomenon of spontaneous four-wave mixing in a highly nonlinear photonic-crystal fiber with a wavelength of one of the photons near 1.5 μm. The demonstrated source can be used as an efficient single photon generator at a telecommunications wavelength with prediction and tuning over a wide spectral range.
In this work, we present a nano-optical scheme of quantum memory for surface plasmon-polariton (SPP) modes in a nanoscale planar waveguide with a resonant atomic ensemble characterized by the periodic structure of the inhomogeneously broadened line. The theoretical study of the SPP modes is presented, where the regime of slow propagation and low-losses was found for these modes with fixed transverse spatial confinement, which provides a strong nondissipative interaction with resonant atoms. We describe the basic physical properties of the studied scheme and demonstrate a perspective area for the implementation of fast nanoscale quantum memory and processing with surface SPP modes.
We propose a composite frequency-scalable quantum memory (QM) scheme based on a system of coupled resonators with single atoms capable of efficient storage of the quantum states of broadband single-photon fields having an arbitrary time form. The analyzed QM consists of 8 high-Q miniresonators coupled to a common resonator that is connected to the external waveguide, where each miniresonator contains a single atom. Based on the methods of optimization of the transfer function, we found the optimal parameters of the QM scheme at which an efficient transfer of a photon wave packet from an external waveguide to the atoms is possible for efficient long-term storage in long-lived atomic states. Various functional modes of using the memory circuit are described and ways to increase efficiency for its use in quantum processing are discussed.
In this work, we present an integrated waveguide-resonator scheme of an atomic quantum transistor with a multi-qubit memory. The quantum transistor is realized in an atomic-photon molecule formed of a linear chain of three interconnected resonators, each of which contains one resonant three-level atom. The resonators are connected through the waveguides to the quantum memory containing long-lived multi-atomic ensembles capable of storage of photonic qubits with an arbitrary temporal mode. We consider the protocols for implementation of one- and two-qubit operations in the proposed scheme over a system of qubits stored in quantum memory. The advantages and experimental implementation of the proposed scheme are also discussed.
We propose a mechanism for increasing the bandwidth of impedance matching in an optical cavity. We demonstrate that placing a compensating medium with abnormal dispersion inside the cavity stretches an optical range by an order of magnitude. As a specific physical system, we consider a double-lambda scheme, where reversible absorption and compensating dispersion could be implemented via two-photon Raman absorption and gain respectively. To prove experimental feasibility of our proposal we study the application of the scheme for an optical quantum storage and provide thorough analysis of possible experimental realizations.
Configuration of three resonators connected located in triangular scheme is considered for implementation of single and two-qubit gates. Each of the resonators can be coupled with its three-level atom and with neighbor resonator in defined moment of time. The regimes for coherent control of atom-photonic molecule states in the studied scheme and realization of single- and two qubit gates on this basis are theoretically investigated. The two qubit gate is considered in two various regimes: at the sequential switching on the interactions with step by step transfer of excitation and when central resonator is coupled simultaneously with two side resonators and excitation is transferring in the course of single process. Comparison of these two approaches is performed and recommendations for the construction of quantum computers on the atom-photon molecular states are presented.
In this paper, we propose a scheme of a long-lived broadband superefficient multiresonator quantum memory in which a common resonator is connected with an external waveguide and with a system of high-quality miniresonators containing long-lived resonant electron spin ensembles. The scheme with 4 miniresonators has been analyzed in details and it was shown that it is possible to store an input broadband signal field to the electron spin ensembles with quantum efficiency 99.99%. The considered multiresonator system opens the way to elaboration of efficient multiqubit quantum memory devices for superconducting quantum computer.
The controllable storage and on demand retrieval of the microwave pulses by using the photon echo quantum memory approach based on a spin frequency comb of inhomogeneous broadening (SFC- protocol) have been demonstrated. We have used an electron-nuclear spin ensemble of tetracyanoethylene anion radicals in toluene which has a natural periodic structure of narrow electron-spin resonance (ESR) hyperfine lines. On-demand retrieval of the stored field has been realized by using two pulses of the magnetic field gradient of an opposite polarity which hold the electron spins in a dephased excited state during the storage time. The obtained experimental results demonstrate promising properties for coherent controlling the electron-nuclear spin ensemble of radicals in liquid that could be useful for implementation of room-temperature broadband quantum memory.
We have studied quantum entanglement generation using nonlinear interaction of slowly propagating quantum field in a solid medium. Due to enhanced nonlinearity based on electromagnetically induced transparency and standing light phenomenon, a reversible nondegenerate four-wave mixing processing results in quantum entanglement generation. Our attention is to determine nonlinear perspectives of the entanglement with single photon fields. To accomplish the quantum entanglement based on the slow light involved standing light scheme, non-Doppler broadening has been required, where multiple atomic coherences have been the basis in a time-reversed manner. This study is potential for nonlinear optics application to quantum information science such as quantum computing and quantum memories using macroscopic optical medium.
We analytically demonstrate a quantum memory based on coherence transfer for manipulating quantum states of photons interacting with a macroscopic medium. The present quantum memory has potential for quantum information and communications using entanglement storage and retrieval. Using this technique the quantum coherent control of a quantum state is effectively possible by simply varying the classical laser parameters.
Femtosecond electron-vibrational dynamics in a gas of diatomic molecules pumped by single-photon quantum field is theoretically investigated on the basis of the femtosecond pump-probe spectroscopy technique. The developed theory is applied for calculation of luminescence signal in a gas of Na2 molecules and it is found that that there is a strong dependence between the form of the temporal spectrum of the signal and the optical density of the medium.
Katzenellenbaum method of cross sections is developed to the calculation of the light field parameters in nearfield microscopy probe. The dynamics of the modes propagation in the narrowing probe is studied when the probe aperture size is less than the wavelength λ of light. The analytical expressions for the modes wave numbers in the taper probe have been obtained, which essentially facilitate the analysis of the field parameters in the probe and allow to save the computing time considerably. The influence of walls inclination corner of the probe on modes amplitudes behavior is determined for the excitation of the probe by the monochromatic light. We demonstrate that the variation of the wall inclination corner can result to essential changing of the spatial field structure in the output probe aperture. Using the cross sections method we have studied the propagation and decreasing of the femtosecond pulse of light with 50 fs pulse duration in the taper probe.
The novel variants of the photon echo technique for the storage and complete reconstruction of the quantum states of one and two photon fields are theoretically investigated. Such new possible schemes are proposed for two types of three-level macroscopic coherent media, where the specific spectral and temporal properties of the quantum dynamics are analyzed. Special physical analysis is devoted to the complete reconstruction of the mapped quantum states at the multipulse restoring, its spatial, temporal and spectral properties. The specific possibilities of the proposed schemes for the quantum computations are also discussed. (Summary only available)
Kinetics of the decay of a dynamical grating formed by nonequilibrium charge carries in thin monocrystalline silicon films under femtosecond laser excitation are studied. A case of limiting concentration of charge carriers is analyzed. Contributions of ambipolar diffusion and Auger- recombination in the decay of a dynamical grating are estimated. At high intensities an effect of the long-lived dynamical grating is discovered.
The paper considers some peculiarities of NaK-type diatomic molecule dynamics at multipulsed excitation by femtosecond laser fields. It is studied how intensity of the laser pulses may affect the form of the electronic-vibrational wave packet. Based on numerical calculations of the luminescence signal it has been found that there are domains of excitation parameters with stable and unstable vibrational dynamics.
Currently, it is obvious [1] that nonstationary tasks of quantum mechanics in more degree differ from those of classical physics than stationary ones. Accordingly, time- domain quantum optics experiments are very important for deepening our knowledge of quantum dynamics. It appears that a single-photon wave (SPW-) packets [2] are the best objects of quantum optics for investigation of the quantum dynamics at macroscopic level. One of the fundamental problems herein is the comprehension of interactions of quantum fields (SPW4MIN and TPW-packets) with macroscopic media. In particular, this is immediately associated with development of our knowledge about the fundamental properties of the irreversibility and of detecting quantum fields. At present, our notion about interaction of quantum fields with a detector, is mainly based on the phenomenological approaches to the properties of the detector [3]. That is why more exact quantum models of macroscopic detectors must be investigated. One of the macroscopic objects, which can be interesting for these purposes is the resonant quantum (Two-,Three-level) medium with phase memory intensively studied in coherent optics. Unusual properties of quantum time-domain interference effects and of photon echoes initiated in resonant media by interactions with an SPW-packet, have been predicted in our works 4LB4-6]. In the present paper study of the quantum dynamics at interaction of the field with the medium we will carry out by investigation of the two photon echo properties. At that, we consider interaction of a three- level (TL-) medium with polarized two-photon wave packets for the purpose of eliciting new nonclassical polarization properties in quantum dynamics of the echo signals.
Kinetics of the decay of transient gratings (four-wave non- simultaneous interaction) in nitrobenzene liquid in the femtosecond time scale is studied. Experimental results are explained in terms of coherent vibrational molecular motion in liquid. A strong dependence of the kinetics of the signal decay on the polarization of the probe field is discovered. The beats of underdamped vibrational modes of nitrobenzene are separated.
Kinetics of spatial-frequency gratings decay determined by inter-atomic interactions of the two-level medium in solids is theoretically investigated. Building of the theory is oriented towards search for such optical experiments in which kinetics of the SFI-gratings could be studied in a simpler way. Analytical solutions for instantaneous diffraction signal and signal of the stimulated photon echo are obtained.
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