arXiv subjects

Vladimir Manucharyan

Publications and source records attributed to Vladimir Manucharyan.

4 recordsLinked to original sources

arXiv2022

Microwave cavity-free hole burning spectroscopy of Er$^{3+}$:Y$_2$SiO$_5$ at millikelvin temperatures

Efficient quantum memory is of paramount importance for long-distance quantum communications, as well as for complex large-scale computing architectures. We investigate the capability of Er$^{3+}$:Y$_2$SiO$_5$ crystal to serve as a quantum memory for the travelling microwave photons by employing techniques developed for dense optical ensembles. In our efforts to do so, we have performed high-resolution microwave spectroscopy of Er$^{3+}$:Y$_2$SiO$_5$, where we identified electronic spin as well as hyperfine transitions. Furthermore, we have explored spectral hole burning technique and studied the spin relaxation process at millikelvin temperatures, determined the main relaxation mechanisms, which lay the groundwork for further studies of the topic.

quant-ph↗

arXiv2020

Superconducting TiN films grown by directional reactive evaporation

We report a novel method of growing strongly-disordered superconducting titanium nitride (TiN) thin films by reactive electron-beam deposition. The normal state sheet resistance and superconducting critical temperature (Tc) can be tuned by controlling the deposition pressure in the range of 1.1*10^-6 to 3.1*10^-5 mbar} and film thickness d from 10nm to 300nm. For 10nm thick films, the sheet resistance reaches 1361 Ω/\square and T_c = 0.77K, which translates into an estimate for the sheet inductance as large as L_\square = 2.4nH/\square. Benefiting from the directionality of reactive evaporation, we fabricated RF test devices with micron-sized dimensions using a resist mask and a lift-off process, which would be impossible with sputtering or atomic layer deposition methods. The spectroscopic measurements result in consistent sheet inductance values in two different device geometries and the quality factors ranged from Q = 300-2200. The loss is likely due to the presence of titanium oxynitride in the morphological composition of our films. The flexibility of the lift-off process suggest applications of reactively-evaporated TiN for making supporting structures around quantum circuits, such as readout resonators or compact on-chip filters.

cond-mat.supr-con↗

arXiv2019

Transport Properties of Near Surface InAs Two-dimensional Heterostructures

Two-dimensional electron systems (2DESs) confined to the surface of narrowband semiconductors have attracted great interest since they can easily integrate with superconductivity (or ferromagnetism) enabling new possibilities in hybrid device architectures and study of exotic states in proximity of superconductors. In this work, we study indium arsenide heterostructures where combination of clean interface with superconductivity, high mobility and spin-orbit coupling can be achieved. The weak antilocalization measurements indicate presence of strong spin-orbit coupling at high densities. We study the magnetotransport as a function of top barrier and density and report clear observation of integer quantum Hall states. We report improved electron mobility reaching up to 44,000 cm$^{2}$/Vs in undoped heterstructures and well developed integer quantum Hall states starting as low as 2.5~T.

cond-mat.mes-hall↗

arXiv2010

Superconducting Nanowires as Nonlinear Inductive Elements for Qubits

We report microwave transmission measurements of superconducting Fabry-Perot resonators (SFPR), having a superconducting nanowire placed at a supercurrent antinode. As the plasma oscillation is excited, the supercurrent is forced to flow through the nanowire. The microwave transmission of the resonator-nanowire device shows a nonlinear resonance behavior, significantly dependent on the amplitude of the supercurrent oscillation. We show that such amplitude-dependent response is due to the nonlinearity of the current-phase relationship (CPR) of the nanowire. The results are explained within a nonlinear oscillator model of the Duffing oscillator, in which the nanowire acts as a purely inductive element, in the limit of low temperatures and low amplitudes. The low quality factor sample exhibits a "crater" at the resonance peak at higher driving power, which is due to dissipation. We observe a hysteretic bifurcation behavior of the transmission response to frequency sweep in a sample with a higher quality factor. The Duffing model is used to explain the Duffing bistability diagram. We also propose a concept of a nanowire-based qubit that relies on the current dependence of the kinetic inductance of a superconducting nanowire.

cond-mat.mes-hall↗