National Repository of Grey Literature 13 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Calculation of potentials and simulation of the behavior of calcium ions in Paul´s linear ion trap
Vadlejch, Daniel ; Oral, Martin ; Lešundák, Adam ; Pham, Minh Tuan ; Čížek, Martin ; Číp, Ondřej ; Slodička, L.
Precision of the experiments performed using trapped ion within Paul’s linear ion trap is highly dependent on the magnitude of ion’s residual motion. Two different radiofrequency driving modes of the electrodes are compared with respect to magnitude of the ion’s micromotion in the direction of trap’s axis. This comparison of the trapped ion’s micromotion is carried by numerical calculation using finite element method for geometry, which corresponds to trap located in laboratory of Institute of Scientific Instruments, Czech Academy of Science in Brno. The results of the calculations show that symmetrical driving mode should be more suitable to attenuation of trapped ion’s micromotion’s axial component.
Phase and group refractive indices of air calculation by fitting\nof phase difference measured using a combination of laser and\nlow-coherence interferometry
Pikálek, Tomáš ; Šarbort, Martin ; Číp, Ondřej ; Pham, Minh Tuan ; Lešundák, Adam ; Pravdová, Lenka ; Buchta, Zdeněk
The air refractive index is an important parameter in interferometric length measurements, since it substantially\naffects the measurement accuracy. We present a refractive index of air measurement method based on monitoring\nthe phase difference between the ambient air and vacuum inside a permanently evacuated double-spaced cell. The cell is placed in one arm of the Michelson interferometer equipped with two light sources—red LED and HeNe laser, while the low-coherence and laser interference signals are measured separately. Both phase and group refractive indices of air can be calculated from the measured signals. The method was experimentally verified by\ncomparing the obtained refractive index values with two different techniques.
Stabilized laser for spectroscopy on trapped calcium ions
Čížek, Martin ; Pham, Minh Tuan ; Lešundák, Adam ; Hucl, Václav ; Řeřucha, Šimon ; Hrabina, Jan ; Lazar, Josef ; Číp, Ondřej
The paper focuses on the ongoing development of clock laser assembly operating at a wavelength of 729 nm, which will be used for 40Ca+ calcium spectroscopy. As a primary source of coherent radiation, a diode laser with an external resonator operating at a wavelength of 729 nm is used. The width of the spectral line of the free-running laser is approx. 300 kHz. The laser is tunable by a piezoelectric actuator in the range of 10 GHz with a maximum bandwidth of 2 kHz. Fast fine-tuning in hundreds of MHz is possible by modulating the pump current of the laser diode with 50MHz bandwidth. The optical frequency of the laser is locked by means of electronic control loops on a resonator with a finesse better than 300 000 with a mode spectral width of approx. 8 kHz. The cavity of the resonator is made of ULE material and placed in a thermally stabilized vacuum chamber. The entire optical assembly is mounted on an active anti-vibration pad in a wooden box plated with acoustic and thermal isolation. The tuning of the primary laser to the resonator mode is detected by the Pound-Drever-Hall technique.
Trapping and cooling of single ions for frequency metrology and quantum optics experiments
Slodička, L. ; Pham, Minh Tuan ; Lešundák, Adam ; Hucl, Václav ; Čížek, Martin ; Hrabina, Jan ; Řeřucha, Šimon ; Lazar, Josef ; Obšil, P. ; Filip, R. ; Číp, Ondřej
Single trapped ions trapped in Paul traps correspond to ideal candidates for realization of extremely accurate optical atomic clocks and practical studies of the light–atom interactions and nonlinear mechanical dynamics. These systems benefit from both, the superb isolation of the ion from surrounding environment and excellent control of its external and internal\ndegrees of freedom, at the same time, which makes them exquisite platforms for experimental studies and applications of light matter interaction at its most fundamental level. The exceptional degree of control of single or few ion's state enabled in past decade number of major advancements in the applications from the fields of experimental quantum information\nprocessing and frequency metrology, including recent realization of scalable Shor's\nalgorithm, fractional uncertainties of the frequency measurements close to 10-18 level, or simulations of complex quantum many-body effects. These results, together with the rapid advancements in the production of low-noise segmented micro-traps, promise prompt access to long-desired regimes of quantum optomechanics and further development and applications\nof optical atomic clocks.
Optical low dispersion rezonator as length sensor using optical frequency comb
Pravdová, Lenka ; Hucl, Václav ; Lešundák, Adam ; Lazar, Josef ; Číp, Ondřej
Ultra-high precis measurements are domain of lasers interferometers. An optical resonator measuring method using broad spectrum of radiation of an optical frequency comb was designed and experimentally verified at our workplace. The measuring of a quantity – a distance of resonator mirrors – is provided by its conversion to the value of repetition frequency of the pulse laser with mode-locked optical frequency comb. In this paper the comparison of the absolute scale of the optical resonator with an incremental interferometer scale is introduced. The incremental interferometer is implemented for verification of the optical resonator scale. The double beam incremental interferometer is operating at the wavelength of 633 nm and the measuring mirror with piezo actuator is used as one of its reflectors. It turns out that the major error signal is the reflection of the periodic nonlinearity of the incremental resonator scale. The relative resolution of our method reaches values up to 10-9 while maintaining measuring scale.
Detection of frequency noise properties of diode laser working on 729 nm
Pham, Minh Tuan ; Čížek, Martin ; Hucl, Václav ; Lazar, Josef ; Hrabina, Jan ; Řeřucha, Šimon ; Lešundák, Adam ; Číp, Ondřej
Paper report on the frequency noise investigation of the Extended Cavity Diode Laser (ECDL), working at 729 nm. The ECDL will be used as an excitation laser for the forbidden transition in a trapped and laser cooled 40Ca+ ion. For that an Hz of sub-Hz level linewidth is required. We present the experimental design for linewidth narrowing and frequency noise analysis. The linewidth is first narrowed with a phase lock loop of the ECDL onto a selected component of an optical frequency comb where the frequency noise was suppressed with a fast electronic servo-loop controller that drives the laser injection current with a high bandwidth.\n
Radio frequency resonator for feeding ion trap
Jedlička, Petr ; Pham, Minh Tuan ; Čížek, Martin ; Pavelka, Jan ; Lešundák, Adam ; Hucl, Václav ; Hrabina, Jan ; Řeřucha, Šimon ; Lazar, Josef ; Číp, Ondřej
Two versions of resonators were designed and manufactured - asymmetric and symmetric.\nThe resonator consists of a coil and capacity of ion trap which makes parallel resonant circuit.\nEnergy is supplied to the resonator through the coupling inductance. Resonator assembly was equipped with outputs for monitoring high-frequency voltage. Both versions have been tuned and tested.\n\n
Laser cooling of the trapped ions for frequency and time metrology
Číp, Ondřej ; Pham, Minh Tuan ; Čížek, Martin ; Lešundák, Adam ; Hucl, Václav ; Hrabina, Jan ; Řeřucha, Šimon ; Jedlička, Petr ; Lazar, Josef
In the laser cooled trapped ions field current research is oriented to yield isolated ions in their basic state of the motion. The detection of the Doppler cooled iont excitation to its quadrupole transition of the electronic structure gives the opportuniny to stabilize highly coherent lasers of the optical frequency of the hundreds of THz. This way a new standart of the time or optical frequencies called „Optical atomic clock“ can be defined. Institute of the Scientific Instruments in Brno in the cooperation with the Department of the Optics of the Palacky University in Olomouc implemented a unique research infrastructure for laser cooling of 40Ca+ ions and subsequent experiments of the quantum mechanics and spectroscopy in a joint laboratory in Brno. Currently 40Ca+ ions are routinely generated and captured. The Doppler cooling of those ions is performed using dipole transition at a wavelength of the 397 nm. Also detection and spectroscopy of the electronic structure of the ion and the presence of his dark resonances is implemented.\n
Lenght characterization of a piezoelectric actuator by use of a mode-locked femtosecond laser
Pravdová, Lenka ; Lešundák, Adam ; Šmíd, Radek ; Číp, Ondřej
Modern laser interferometers with high resolution are considered as very precise sensors for length measurement. We assembled a specialized optical resonator using silver mirrors. The femtosecond laser with a repetition frequency of 250 MHz and a central wavelength 1560 nm of supercontinuum is used. Femtosecond laser is stabilized by optical frequency comb technique, ie. the frequency offset fCEO and repetition frequency frep is synchronized by our ultra-stable frequency source - hydrogen maser. The technique of derivative spectroscopy is used for locking the resonance peaks of the resonator component of the supercontinuum. The frequency frep in fine steps in the desired range of values is changed via control electronics. This was achieved by changing the length of the cavity in the order of several hundred of nanometers. Repetition frequency change is carried out so that the entire range of the length of the actuator is tested. Value of the applied voltage is recorded for every measured point of the characteristics. The result is a measured characteristic hysteresis curve of the PZT actuator.
Distribution of the accurate optical frequency and time via photonic networks in the Czech Republic
Číp, Ondřej ; Čížek, Martin ; Pravdová, Lenka ; Hucl, Václav ; Řeřucha, Šimon ; Hrabina, Jan ; Lešundák, Adam ; Mikel, Břetislav ; Lazar, Josef ; Vojtěch, J. ; Smotlacha, V.
To verify the stability of the frequency of optical clock an intensive research in the transmission of stable frequency via optical fibers is in progress for many years. Interconnection of large cities and metropolitan networks with optical fiber running DWDM allowing to transfer many optical signals in parallel over one fiber at the same time contributes significantly to troubleshoot the problem. Between nodes of ISI Brno and the main center of CESNET there are several dedicated bi-directional channels through the DWDM technology. The first tests are ongoing with the transfer of accurate time, which are using the possibility of bi-directional communication over a single fiber, thus the phase delay including Doppler shift are reflected on the two signals as well. From periodic measurements can subsequently be evaluated daily, weekly and seasonal fluctuations of the delay and after deduction of such data from the measured data a mutual stability of used time normal can be determined. The second technique is a full compensation of phase of the laser wave through active control of phase changes of the wave during its transmission from the ISI to the node of CESNET. At present, a characterization of the behavior of individual system elements, including their commissioning is in progress.

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