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N. Abramov

Publications and source records attributed to N. Abramov.

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Towards practical non-Markovianity measures: Normalization and regularization techniques

Measures characterizing the non-Markovianity degree of the quantum dynamics have several drawbacks when applied to real devices. They depend on the chosen measurement time interval and are highly sensitive to experimental noise and errors. We propose several techniques to enhance the practical applicability of the measures and verify our findings experimentally on a superconducting transmon and a trapped-ion qubit. The time dependence can be disregarded by introduction of the measure per oscillation, while the sensitivity to noise is reduced by applying a regularization procedure. The results for both types of qubits are compared with theoretical predictions for a simple model of non-Markovianity based on qubit-qubit interaction.

quant-ph

Broadband Sample Holder for Microwave Spectroscopy of Superconducting Qubits

We present a practical design and implementation of a broadband sample holder suitable for microwave experiments with superconducting integrated circuits at millikelvin temperatures. Proposed design can be easily integrated in standard dilution cryostats, has flat pass band response in a frequency range from 0 to 32 GHz, allowing the RF testing of the samples with substrate size up to 4x4 mm. The parasitic higher modes interference in the holder structure is analyzed and prevented via design considerations. The developed setup can be used for characterization of superconducting parametric amplifiers, bolometers and qubits. We tested the designed sample holder by characterizing of a superconducting flux qubit at 20 mK temperature.

cond-mat.supr-con