Proposal for Trapped-Ion Quantum Memristor.

A quantum memristor combines the memristive dynamics with the quantum behavior of the system. We analyze the idea of a quantum memristor based on ultracold ions trapped in a Paul trap. Corresponding input and output memristor signals are the ion electronic levels populations.

48 -cm-long room-temperature cavities in vertical and horizontal orientations for Sr optical clock.

The development of an optical clock with ultimate accuracy and stability requires lasers with very narrow linewidths. We present two ultrastable laser systems based on 48-cm-long Fabry-Perot cavities made of ultralow expansion glass in horizontal and vertical configurations operating at 698 nm. Fractional frequency instability of the beat signal between the two lasers reaches 1.

Simultaneous bicolor interrogation in thulium optical clock providing very low systematic frequency shifts.

Optical atomic clocks have already overcome the eighteenth decimal digit of instability and uncertainty, demonstrating incredible control over external perturbations of the clock transition frequency. At the same time, there is an increasing demand for atomic (ionic) transitions and new interrogation and readout protocols providing minimal sensitivity to external fields and possessing practical operational wavelengths. One of the goals is to simplify the clock operation while maintaining the relative uncertainty at a low 10 level achieved at the shortest averaging time.

Inner-shell clock transition in atomic thulium with a small blackbody radiation shift.

One of the key systematic effects limiting the performance of state-of-the-art optical clocks is the blackbody radiation (BBR) shift. Here, we demonstrate unusually low sensitivity of a 1.14 μm inner-shell clock transition in neutral Tm atoms to BBR.

Loading of mass spectrometry ion trap with Th ions by laser ablation for nuclear frequency standard application.

We describe an original multisectional quadrupole ion trap aimed to realize nuclear frequency standard based on the unique isomer transition in thorium nucleus. It is shown that the system effectively operates on Th, Th and Th ions produced by laser ablation of metallic thorium-232 target. Laser intensity used for ablation is about 6 GW/cm.

Mass selective laser cooling of Th in a multisectional linear Paul trap loaded with a mixture of thorium isotopes.

We consider an experiment on trapping and laser cooling of Th ions in a linear Paul trap in the presence of undesirable impurities such as ions of the radioactive isotope Th. We suggest a method of separating these impurities by means of selective laser cooling utilizing the isotope shift of cooling transitions in Th and Th ions. According to our estimation, the isotope shift is equal to 3.

The Rydberg constant and proton size from atomic hydrogen.

At the core of the "proton radius puzzle" is a four-standard deviation discrepancy between the proton root-mean-square charge radii () determined from the regular hydrogen (H) and the muonic hydrogen (µp) atoms. Using a cryogenic beam of H atoms, we measured the 2S-4P transition frequency in H, yielding the values of the Rydberg constant = 10973731.568076(96) per meterand = 0.

Active fiber-based retroreflector providing phase-retracing anti-parallel laser beams for precision spectroscopy.

We present an active fiber-based retroreflector providing high quality phase-retracing anti-parallel Gaussian laser beams for precision spectroscopy of Doppler sensitive transitions. Our design is well-suited for a number of applications where implementing optical cavities is technically challenging and corner cubes fail to match the demanded requirements, most importantly retracing wavefronts and preservation of the laser polarization. To illustrate the performance of the system, we use it for spectroscopy of the 2S-4P transition in atomic hydrogen and demonstrate an average suppression of the first order Doppler shift to 4 parts in 10 of the full collinear shift.