Low-noise computer-controlled current source for quantum coherence experiments
| Autor: | T. Hime, Britton Plourde, P. A. Reichardt, Sven Linzen, Timothy Robertson, John Clarke |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | Review of Scientific Instruments. 75:2541-2544 |
| ISSN: | 1089-7623 0034-6748 |
| DOI: | 10.1063/1.1771499 |
| Popis: | We describe a dual current source designed to provide static flux biases for a superconducting qubit and for the Superconducting QUantum Interference Device (SQUID) which measures the qubit state. The source combines digitally programmable potentiometers with a stabilized voltage source. Each channel has a maximum output of ±1 mA, and can be adjusted with an accuracy of about ±1 nA. Both current supplies are fully computer controlled and designed not to inject digital noise into the quantum bit and SQUID during manipulation and measurement of the flux. For a 275 μA setting, the measured noise current is 2.6 parts per million (ppm) rms, in a bandwidth of 0.0017–10 Hz, from which we estimate dephasing times of hundreds of nanoseconds in the particular case of our own qubit design. By resetting the current every 10 min, we are able to reduce the drift to no more than 5 ppm at a current of 750 μA over a period of 3 days. The current source has been implemented without thermal regulation inside a radiofrequenc... |
| Databáze: | OpenAIRE |
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