Editing Rapid single flux quantum (section)

== Disadvantages ==

* Requires [[cryogenic]] cooling.  Traditionally this has been achieved using cryogenic liquids such as [[liquid nitrogen]] and [[liquid helium]].  More recently, closed-cycle cryocoolers, e.g.,  [[pulse tube refrigerator]]s have gained considerable popularity as they eliminate cryogenic liquids which are both costly and require periodic refilling.  Cryogenic cooling is also an advantage since it reduces the working environment's [[thermal noise]].
* The cooling requirements can be relaxed through the use of [[high-temperature superconductor]]s. However, only very-low-complexity RFSQ circuits have been achieved to date using high-''T''<sub>c</sub> superconductors. It is believed that SFQ-based digital technologies become impractical at temperatures above ~ 20&nbsp;K – 25&nbsp;K because of the exponentially increasing bit error rates (thermally-induced junction switching) cause by decreasing of the parameter ''E''<sub>J</sub>/''k''<sub>B</sub>''T'' with increasing temperature ''T'', where ''E''<sub>J</sub> = ''I''<sub>c</sub>Φ<sub>0</sub>/2π is the [[Josephson energy]].  
* Static power dissipation that is typically 10–100 times larger than the dynamic power required to perform logic operations was one of the drawbacks. However, the static power dissipation was eliminated in ERSFQ version of RSFQ by using superconducting inductors and Josephson junctions instead of bias resistors, the source of the static power dissipation.