Josephson Qubits as Probes of 1/f Noise

Abstract

Quantum mechanical manipulations ("quantum state engineering") of solidstate systems is one of the most rapidly developing areas of research. Substantial progress has been achieved with superconducting circuits based on Josephson junctions. Solid-state building blocks of quantum computers have the advantages that they can be switched quickly, and they can be integrated into electronic control and measuring circuits. Strong coupling to the external circuits and other parts of the environment brings with it the problem of noise and, thus, decoherence. Therefore, the study of sources of decoherence is necessary. On the other hand, the Josephson qubits have found their first application as sensitive spectrometers of the surrounding noise.

Dual-probe decoherence microscopy: Probing pockets of coherence in a decohering environment

“…Such perturbations at the same time contain information about the surrounding environment which generates them. The idea of using qubits as probes of their environment has recently generated interest [1,2,3,4,5] as an alternative application of qubit technology where the effects of decoherence are used, rather than suppressed.…”