Abstract
The noise temperature of a dc superconducting quantum interference device (SQUID) coupled to a tuned input circuit is computed using the complete quantum expression for the equilibrium noise in the shunt resistance of each junction. At T = 0, where the noise reduces to zero-point fluctuations, the noise temperature for an optimized system is hn/kB ln2, where n is the signal frequency. The computation is extended to nonzero temperatures, and it is shown that a SQUID operated at 1K can approach the quantum limit.
Original language | English (US) |
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Pages (from-to) | 380-382 |
Number of pages | 3 |
Journal | Applied Physics Letters |
Volume | 38 |
Issue number | 5 |
DOIs | |
State | Published - 1981 |
Externally published | Yes |
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)