- 标题
- 摘要
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- 实验方案
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Frequency shift of an optical cavity mode due to a single-atom motion
摘要： Using quantum coherence effects, we have developed a new technique of detection of motion of single atoms or ions in an optical cavity. We have theoretically demonstrated that the presence of a single atom or ion inside cavity leads to a shift in cavity frequency and phase of transmitted probe beams. It has been shown by the use of EIT technique, the change of the phase is extremely sensitive to probe detuning in the vicinity of resonance frequency and can be in the order of 10?4.
关键词： optical cavity,frequency shift,Single-atom detector,phase shift,quantum coherence
更新于2025-09-23 15:22:29
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A direct diode pumped Ti:sapphire laser with single-frequency operation for high resolution spectroscopy
摘要： A direct diode pumped continuous-wave Ti:sapphire laser (DDPTS) is presented. A bow-tie geometry with optical diode is chosen for unidirectional single-mode operation. Frequency selection is performed with a standard combination of birefringent filter and etalon. To accomplish mode-hop free frequency tuning the piezo-driven etalon is stabilized to one of the cavity modes via dither-locking method. To suppress environmental fluctuations the cavity-mode is additionally locked to an external optical cavity with low frequency drift. Feasibility of the setup for high-resolution spectroscopy is demonstrated by saturated absorption spectroscopy of the D2 line of Rubidium.
关键词： Rubidium,Stabilization,Hyperfine structure,Laser,Titanium:sapphire,Optical cavity,Beatnote
更新于2025-09-23 15:21:01
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Optimal storage of a single photon by a single intra-cavity atom
摘要： We theoretically analyze the efficiency of a quantum memory for single photons. The photons propagate along a transmission line and impinge on one of the mirrors of a high-finesse cavity. The quantum memory is constituted by a single atom within the optical resonator. Photon storage is realized by the controlled transfer of the photonic excitation into a metastable state of the atom and occurs via a Raman transition with a suitably tailored laser pulse, which drives the atom. Our study is supported by numerical simulations, in which we include the modes of the transmission line and we use the experimental parameters of existing experimental setups. It reproduces the results derived using input–output theory in the corresponding regimes and can be extended to compute dynamics where the input–output formalism cannot be straightforwardly applied. Our analysis determines the maximal storage efficiency, namely, the maximal probability to store the photon in a stable atomic excitation, in the presence of spontaneous decay and cavity parasitic losses. It further delivers the form of the laser pulse that achieves the maximal efficiency by partially compensating parasitic losses. We numerically assess the conditions under which storage based on adiabatic dynamics is preferable to non-adiabatic pulses. Moreover, we systematically determine the shortest photon pulse that can be efficiently stored as a function of the system parameters.
关键词： single photon,three level system,storage efficiency,optical cavity,single atom,quantum memory
更新于2025-09-23 15:21:01
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Optical Fredkin gate assisted by quantum dot within optical cavity under vacuum noise and sideband leakage
摘要： We propose a deterministic fredkin gate which can accomplish controlled-swap operation between three-qubit states. the proposed fredkin gate consists of a photonic system (single photon) and quantum dots (QDs) confined in single-sided cavities (two electron spin states). In our scheme, the control qubit is the polarization state of the single photon, and two electron spin states in QDs play the role of target qubits (swapped states by control qubit). the interaction between a photon and an electron of QD within the cavity (QD-cavity system) significantly affects the performance of Fredkin gate. Thus, through the analysis of the QD-cavity system under vacuum noise and sideband leakage, we demonstrate that reliable interaction and performance of the QD-cavity system with photonic state (photon) can be acquired in our scheme. Consequently, the Fredkin gate proposed in this paper can be experimentally implemented with high feasibility and efficiency.
关键词： quantum dot,Fredkin gate,sideband leakage,optical cavity,vacuum noise
更新于2025-09-23 15:19:57
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[IEEE 2019 Joint Conference of the IEEE International Frequency Control Symposium anEuropean Frequency and Time Forum (EFTF/IFC) - Orlando, FL, USA (2019.4.14-2019.4.18)] 2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC) - Ultrastable Laser System Using Room-Temperature Optical Cavity with 4.8??10 <sup>a??17</sup> Thermal Noise Limit
摘要： A new clock laser system using an optical cavity with 4.8×10-17 thermal noise limit has been developed for rapid evaluation of ytterbium lattice clocks. This was realized by using a 30-cm-long ULE cavity, fused-silica mirror substrates, and crystalline mirror coatings. The frequency stability of the beating signal between the new clock laser and the old clock laser was limited by the latter. The linewidth and the frequency stability of the new clock laser will be measured by comparing the frequency between two similar systems.
关键词： linewidth,ytterbium,optical lattice clock,frequency stability,optical cavity,clock laser,crystalline coating
更新于2025-09-19 17:13:59
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Laser-Based Phase Contrast for Transmission Electron Microscopy
摘要： Laser control of free electrons has been used to advance the exploration of matter on the atomic scale. For example, temporal modulation of electron waves with light has enabled the study of transient processes with attosecond resolution. By contrast, laser-based spatial shaping of the electron wave function has not yet been realized, even though it could be harnessed to probe radiation-sensitive systems, such as biological macromolecules, at the standard quantum limit and beyond. We demonstrate increased image contrast by laser control of the spatial phase profile of the electron wave function in transmission electron microscopy (TEM). We first realize an electron interferometer, using continuous-wave laser-induced retardation to coherently split the electron beam, and capture TEM images of the light wave. We then demonstrate Zernike phase contrast by using the laser beam to shift the phase of the electron wave scattered by a specimen relative to the unscattered wave. Electrons interact with light via the repulsive ponderomotive potential arising from stimulated Compton scattering. Due to the short electron-light interaction time in a micron-scale laser focus, retardation of the relativistic electrons used in TEM requires an intensity of tens of GW/cm2. Such intensities have so far only been attained with pulsed lasers, but a cw laser is needed in order to work state-of-the-art, continuously operating TEM. The requisite laser intensity is generated by 4000-fold resonant power enhancement in a near-concentric Fabry-Perot optical cavity with a mode waist of w0 = 13 μm. A laser system consisting of a fiber amplifier seeded by a low-power master laser supplies an input laser beam at a wavelength of λ = 1064 nm. The experiments are carried out with 80 keV electrons, in a custom-modified TEM (FEI Titan) equipped with additional electron optics that magnify the diffraction pattern to an effective focal length of f = 20 mm. The cavity is suspended in the TEM column, with its axis orthogonal to the electron beam propagation direction and with the mode waist positioned close to the center of the magnified electron diffraction plane, as shown in Fig. 1. Zernike phase contrast is evident in a typical close-to-focus image (Fig. 1), showing the structure of the carbon film. A high-intensity CW laser field generates Zernike phase contrast in a TEM and significantly increases the image contrast at low spatial frequencies. Such a phase plate will enable dose-efficient data collection in single-particle analysis of biological macromolecules, electron tomography of vitrified cells, and imaging of sensitive materials science specimens. The controllable phase shift in this device can also be used for holographic reconstruction of the post-specimen wave function. Work in the immediate future will include working with 300-keV electrons, which requires constructing a new cavity with lower-loss optical coatings to reach higher laser intensity. We will also study and optimize the imaging properties of the phase-contrast TEM, and apply it to structural biology.
关键词： Zernike phase contrast,Laser control,Fabry-Perot optical cavity,Transmission Electron Microscopy,electron wave function
更新于2025-09-19 17:13:59
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Electrically Tunable Liquid-Crystala??Polymer Composite Laser with Symmetric Sandwich Structure
摘要： This study investigates and develops for the first time an electrically tunable liquid-crystal?polymer composite laser with a symmetric sandwich structure. This structure includes two identical polymer-stablized cholesteric liquid-crystal (PSCLC) layers, and a dye-doped nematic LC (DDNLC) layer is sandwiched between them. The PSCLC and DDNLC layers act as distributed Bragg reflectors and half-wave plate with a gain medium, respectively. The entire cell behaves as an optical cavity, where the resonant modes occur at the maxima of the cell’s transmission spectrum. Through the competition among the resonant modes by considering the gain and loss, the resonant mode with the lowest lasing threshold can be sieved out for lasing occurrence. When the same voltage is applied to the two PSCLC layers, the pitch gradients are simultaneously formed through the two layers because of the electrically induced ion-concentration gradients. When the voltage increases, the pitch gradients increase, thereby leading to the expansion of the cell photonic band gap (PBG) and blue shift of the lasing wavelength. The sandwich cell PBG can expand from 55 nm to over 170 nm, and the tuning range of the lasing wavelength is as high as 70 nm, which is the widest ever achieved in LC-related sandwich systems. The proposed configuration of the sandwich sample presents new insights into tunable LC PBG and laser devices, thereby providing potential applications in the form of sensors, medical imaging, displays and lighting, among others.
关键词： distributed Bragg reflectors,electrically tunable,dye-doped nematic LC,photonic band gap,liquid-crystal?polymer composite laser,optical cavity,symmetric sandwich structure,half-wave plate,lasing wavelength,polymer-stablized cholesteric liquid-crystal
更新于2025-09-19 17:13:59
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Collective dynamics of inhomogeneously broadened emitters coupled to an optical cavity with narrow linewidth
摘要： We study collective effects in an inhomogeneously broadened ensemble of two-level emitters coupled to an optical cavity with narrow linewidth. Using second-order mean-field theory we find that the emitters within a few times the cavity linewidth exhibit synchronous behavior and undergo collective Rabi oscillations. Under proper conditions, the synchronized oscillations give rise to a modulated intracavity field which can excite emitters detuned by many linewidths from the cavity resonance. To study the synchronization in further detail, we simplify the model and consider two ensembles and study steady-state properties when the emitters are subjected to an incoherent drive.
关键词： collective dynamics,optical cavity,Rabi oscillations,inhomogeneous broadening,synchronization
更新于2025-09-12 10:27:22
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Description of an air temperature sensor based on O2 absorption spectroscopy
摘要： In this paper, we describe in detail an assembled open-path optical cavity to act as a temperature sensor of air. A metal absorption cell in a temperature-regulated tube furnace is placed at the center of an optical cavity. The optical cavity consists of two mirrors, two nitrogen buffer sleeves, and the open cell. The air is injected through a ?tting in one extreme of the metal tube and travels half the tube length through a channel in the wall of the tube. The channel directs the air towards the center of the cell. The air ?owing is heated at the temperature of the metal tube in contact with the furnace. The heated air injected at the center of the tube, ?ows towards the open extremes of the tube. The nitrogen buffer sleeves protect the mirrors from the heated air. The temperature of the air ?owing through the tube is determined by measuring the absorption of the A band of oxygen as a function of the wavenumber in the 769–755 nm wavelength range. The absorption technique is phase-shift cavity ring down spectroscopy. To obtain the temperature, the energy of the lower rotational state for eleven selected rotational transitions is linearly ?tted to a logarithmic function that contains the relative intensity of the rotational transition, the initial and ?nal rotational quantum numbers and the energy of the transition. Accuracy of the measurement is determined by comparing the calculated temperature from the spectra with the analog reading of the temperature-regulated tube furnace. This technique is proposed for exhaust air temperature measurements of combustion chambers and cooling air after passing through the blades of a turbine.
关键词： Flowing air,Optical cavity,Temperature sensor,Oxygen,Cavity ring down,A-band
更新于2025-09-10 09:29:36
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A vibration-insensitive-cavity design holds impact of higher than $$100g$$100g
摘要： In this paper, we report a robust and vibration insensitive optical cavity design. The robustness of the supporting structure was tested by dropping an aluminum and a ULE cavity model mounted in the supporting frame onto an optical table from a height of about 250 and 20 mm repetitively. The impact acceleration on hitting the table was estimated to be higher than 100g. The success of the test demonstrated that the design was very robust. Meanwhile, the vibration sensitivities of the cavity in three orthogonal directions were measured to be 0.8 × 10?10∕g, 2.5 × 10?10∕g and 1.5 × 10?10∕g, respectively. The robustness and low vibration sensitivity suggested that the design was suitable for transportable system and might be a good candidate for space applications.
关键词： Optical cavity,Space,Transportable,Ultra-stable laser
更新于2025-09-10 09:29:36