arXiv subjects

M. Khabipov

Publications and source records attributed to M. Khabipov.

4 recordsLinked to original sources

arXiv2022

Superconducting microwave resonators with non-centrosymmetric nonlinearity

We investigated both theoretically and experimentally open-ended coplanar waveguide resonators with rf SQUIDs embedded in the central conductor at different positions. These rf SQUIDs can be tuned by an external magnetic field and thus may exhibit the non-centrosymmetric nonlinearity of $χ^{(2)}$ type with suppressed Kerr nonlinearity. We demonstrated that this nonlinearity allows for efficient mixing of $λ/2$ and $λ$ modes in the cavity and thus enables various parametric effects with three wave mixing. These effects are the second harmonic generation, the half tone generation, the parametric amplification in both degenerate and non-degenerate regimes and deamplification in degenerate regime.

cond-mat.supr-con↗

arXiv2019

DC measurement of dressed states in a coupled 100~GHz resonator system using a single quasiparticle transistor as a sensitive microwave detector

We report on the on-chip detection of microwaves in the frequency range around 100GHz. For the purpose of detection, we employ a discrete transport channel triggered in a superconducting single-electron transistor by photon-assisted tunneling of quasiparticles. The technique is successfully applied to observe the spectrum of the dressed states of a model cQED system consisting of a superconducting coplanar resonator coupled to a quantum Josephson oscillator. The dressed states appear as typical resonance anticrossing exhibiting, in our case, an expectedly wide frequency splitting corresponding to the Jaynes-Cummings coupling strength, g/pi~10GHz. Due to the high decay rate, gamma~20-40GHz, in the very transparent Josephson junctions used, the strong coupling limit, g>>gamma, which is required for qubit operation, is not achieved, and the photon population in the resonator is low, ~1. Remarkably, the continuous readout of the low population states demonstrates the high microwave sensitivity of the detector.

cond-mat.supr-con↗

arXiv2017

Traveling-wave parametric amplifier based on three-wave mixing in a Josephson metamaterial

We have developed a recently proposed Josephson traveling-wave parametric amplifier with three-wave mixing [A. B. Zorin, Phys. Rev. Applied 6, 034006, 2016]. The amplifier consists of a microwave transmission line formed by a serial array of nonhysteretic one-junction SQUIDs. These SQUIDs are flux-biased in a way that the phase drops across the Josephson junctions are equal to 90 degrees and the persistent currents in the SQUID loops are equal to the Josephson critical current values. Such a one-dimensional metamaterial possesses a maximal quadratic nonlinearity and zero cubic (Kerr) nonlinearity. This property allows phase matching and exponential power gain of traveling microwaves to take place over a wide frequency range. We report the proof-of-principle experiment performed at a temperature of T = 4.2 K on Nb trilayer samples, which has demonstrated that our concept of a practical broadband Josephson parametric amplifier is valid and very promising for achieving quantum-limited operation.

cond-mat.supr-con↗

arXiv2010

Implementation of superconductor-ferromagnet-superconductor pi-shifters in superconducting digital and quantum circuits

The difference between the phases of superconducting order parameter plays in superconducting circuits the role similar to that played by the electrostatic potential difference required to drive a current in conventional circuits. This fundamental property can be altered by inserting in a superconducting circuit a particular type of weak link, the so-called Josephson $π$-junction having inverted current-phase relation and enabling a shift of the phase by $π$. We demonstrate the operation of three superconducting circuits -- two of them are classical and one quantum -- which all utilize such $π$-phase shifters realized using superconductor-ferromagnet-superconductor sandwich technology. The classical circuits are based on single-flux-quantum cells, which are shown to be scalable and compatible with conventional niobium-based superconducting electronics. The quantum circuit is a $π$-phase biased qubit, for which we observe coherent Rabi oscillations and compare the measured coherence time with that of conventional superconducting phase qubits.

cond-mat.supr-con↗