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Laser ablation of calcium atoms for laser cooling experiment
Grim, Jakub ; Pham, Minh Tuan ; Číp, Ondřej
Our work describes two most common methods of generating neutral atoms needed for experiments with trapped and cooled ions. The easiest but not most effective way of the neutral atoms generating is to use a heated oven. A better method allowing a fine control of generating atoms is to use a pulsed laser ablation. A vacuum chamber with Ca atoms source and necessary optics was assembled. Detection of generated particles was achieved by laser-induced fluorescence and sensitive camera. The paper consists of measurement of both method of generating the atoms.
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Orbital motion from optical spin: the extraordinary momentum of circularly polarized light beams
Svak, Vojtěch ; Brzobohatý, Oto ; Šiler, Martin ; Jákl, Petr ; Zemánek, Pavel ; Simpson, Stephen Hugh
We provide a vivid demonstration of the mechanical effect of transverse spin momentum in an\noptical beam in free space. This component of the Poynting momentum was previously thought\nto be virtual, and unmeasurable. Here, its effect is revealed in the inertial motion of a probe\nparticle in a circularly polarized Gaussian trap, in vacuum. Transverse spin forces combine with\nthermal fluctuations to induce a striking range of non-equilibrium phenomena. With increasing\nbeam power we observe (i) growing departures from energy equipartition, (ii) the formation of\ncoherent, thermally excited orbits and, ultimately, (iii) the ejection of the particle from the trap.\nOur results complement and corroborate recent measurements of spin momentum in evanescent\nwaves, and extend them to a new geometry, in free space. In doing so, we exhibit fundamental,\ngeneric features of the mechanical interaction of circularly polarized light with matter. The work\nalso shows how observations of the under-damped motion of probe particles can provide detailed\ninformation about the nature and morphology of momentum flows in arbitrarily structured light\nfields as well as providing a test bed for elementary non-equilibrium statistical mechanics.
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Analysis of linear ion Paul traps using 3-D FEM and the azimuthal multipole expansion
Oral, Martin ; Číp, Ondřej ; Slodička, L.
Radiofrequency (RF) Paul traps are valuable in the design and in the operation of highly stable\noptical atomic clocks based on suitable trapped ions. The traditional setup involves a single\nion in an RF trap irradiated with a laser beam. The frequency of the laser light is then fine-tuned to match that of photons coming from an electronic transition in the atomic shell. The\nachievable frequency stability is about 10-17 for laser-cooled ions. However, the stability can be\nfurther improved by using heavy atoms (such as Thorium) and the more stable frequencies of\ntheir nuclear transitions, and by setting up so-called Coulomb crystals, to improve the frequency measurement statistics by increasing the number of reference atoms. These techniques and their combination could reach relative stabilities beyond 10-20.
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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.
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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.
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Frequency stabilized semiconductor laser source for high-resolution interferometry
Řeřucha, Šimon ; Hucl, Václav ; Holá, Miroslava ; Čížek, Martin ; Pham, Minh Tuan ; Pravdová, Lenka ; Lazar, Josef ; Číp, Ondřej
We have assembled an experimental iodine stabilized Distributed Bragg Reflector (DBR) diode based laser system lasing at a wavelength that is in a close proximity to the wavelength of a stabilized He-Ne lasers traditionally used for metrological applications (λ=632.9 nm in vacuum). The aim was to verify whether such a system could be used as an alternative to the He-Ne laser while yielding wider optical frequency tuning range, higher output power and high frequency modulation capability. We have measured the basic characteristics of the laser source and then we have compared the performance of the laser system with that of a traditional frequency stabilized He-Ne laser with a series of experimental arrangements similar to those usually found in laser interferometry and displacement metrology applications. The results indicate that DBR diode laser system provides a good laser source for applications in dimensional (nano)metrology since it provides more output power and advanced tunability options than stabilized He-Ne lasers while maintaining fundamental requirements such as the frequency stability, coherence length and also a defined traceability.\n\n
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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.
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