Microwave radiation of a single (angular) frequency ω ω can induce quantized DC voltages across the Josephson junction, in which case the Josephson phase takes the form φ φ ( t ) = φ φ 0 + n ω ω t + a sin ⁡ ⁡ ( ω ω t ) , and the voltage and current across the junction will be: V ( t ) = ℏ ℏ 2 e ω ω ( n + a cos ⁡ ⁡ ( ω ω t ) ) , and I ( t ) = I c ∑ ∑ m = − − ∞ ∞ ∞ ∞ J m ( a ) sin ⁡ ⁡ ( φ φ 0 + ( n + m ) ω ω t ) ,