Dephasing of a superconducting qubit induced by photon noise

We have studied the dephasing of a superconducting flux qubit coupled to a dc-SQUID based oscillator. By varying the bias conditions of both circuits we were able to tune their effective coupling strength. This allowed us to measure the effect of such a controllable and well-characterized environmen...

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Bibliographic Details
Published in:Physical review letters 2005-12, Vol.95 (25), p.257002.1-257002.4, Article 257002
Main Authors: BERTET, P, CHIORESCU, I, BURKARD, G, SEMBA, K, HARMANS, C. J. P. M, DIVINCENZO, D. P, MOOIJ, J. E
Format: Article
Language:English
Subjects:
Applied sciences
Classical and quantum physics: mechanics and fields
Electronics
Exact sciences and technology
Physics
Quantum computation
Quantum information
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Superconducting devices
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Summary:We have studied the dephasing of a superconducting flux qubit coupled to a dc-SQUID based oscillator. By varying the bias conditions of both circuits we were able to tune their effective coupling strength. This allowed us to measure the effect of such a controllable and well-characterized environment on the qubit coherence. We can quantitatively account for our data with a simple model in which thermal fluctuations of the photon number in the oscillator are the limiting factor. In particular, we observe a strong reduction of the dephasing rate whenever the coupling is tuned to zero. At the optimal point we find a large spin-echo decay time of .
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.95.257002