This general method can be used for any qubit system. Measure the spectrum of low-frequency noise. Josephson phase qubit that uses the resonant response of the qubit to directly In this Letter we present the results of a novel measurement in a To the measured dephasing times of superconducting qubits ( nakamura, johnPRB, kochNew, ). Now it seems clear that theĮxcess low-temperature noise of these SQUIDs is intimately connected Noise in these experiments was never understood, and the issue has The origin of the excess low temperature flux With a canonical value at 1 Hz of about 2 μ Φ 0 / √ Hz. Parameters such as SQUID loop inductance, geometry, material, etc., Noise was seen to be only weakly dependent on a wide range of device Power spectrum which scaled like 1 / f α at low frequencies, Researchers found that the devices displayed a flux noise with a
FLUX NETWORKS CANT CREAK FLUX SERIES
More that 20 years ago in a series ofĮxperiments on SQUIDs cooled to millikelvin temperatures, QUantum Interference Devices (SQUIDs) kochOld wellstood. Low-frequency noise in superconducting circuits has been studied forĭecades in the context of amplifiers based on the Superconducting Moreover, the magnitude of the flux noise inferred from qubit Ramseyįringe experiments is of the order of several μ Φ 0 / √ Hzįor both three-junction flux qubits and phase qubits, despite a difference in loop inductance of almost two To arise from a magnetic flux noise applied to the qubit loop, withĪ spectral density that scales inversely with frequency ( 1 / f ). In the case of the Josepshon flux qubit and theįlux-biased Josephson phase qubit, these fluctuations are believed Dephasing is produced by low-frequency fluctuations in Which can be implemented, and represents a significant obstacle to Present dephasing times are in the 100’s of ns range the shortĬoherence places a strict limit on the number of gate operations
FLUX NETWORKS CANT CREAK FLUX FULL
However, to realize the full potential of Josephson junctionsįor QIP, it will be necessary to extend qubit dephasing times. Understood johnPRL, and steady improvements can be expected in the coming Moreover, the dominant mechanism for energy relaxation is becoming Milestones, including single and coupled qubit state tomography matthiasPRL matthias. Quantum bits (qubits)īased on Josephson junctions have already achieved several key Scalable quantum information processing (QIP) general.
Superconducting integrated circuits are a leading candidate for
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