The dc bias current, I B , is made greater than I o . The superconducting SQUID ring circuit undergoes the phenomenon of fluxoid quantization in which the magnetic flux linking the SQUID is given by n? o . n is an integer and ? o is the flux quantum, equal to h=2q ¼ 2?10 ?15 Wb. If we apply an additional flux, ? i , through the SQUID ring, a supercurrent, I S ¼ ?? I =L is set up in the ring to create a flux which cancels ?