Ultra high resolution Josephson sampling technique

A sampling system for measuring unknown signals, comprising:

• a monitor gate having at least two distinguishable states to which said unknown signal is applied as a control signal along with a sampling pulse and an adjustable bias signal,
• switching means for switching the state of said monitor gate, said switching means including a source of said unknown signal, a source of said sampling pulse, and a source of said adjustable bias signal,
• noise elimination means for unambiguously defining the switching threshold of said monitor gate, said noise elimination means including means for time averaging the output of said monitor gate and being connected in a feedback loop between said source of bias signals and said monitor gate, said means for time averaging including means for applying an error signal to said source of bias signals in order to adjust the amplitude of said bias signal to that exact amplitude which switches the state of said monitor gate,
• a monitor gate source for providing a signal through said monitor gate of a predetermined value,
• timing means for providing a timing reference and an accurate sampling delay time, said timing means including means for initiating the sampling of said unknown signal by said monitor gate and means for establishing a sampling delay time, said timing means including said source of sample pulses and a delay means for establishing a delay in the application of said sample pulses with respect to the application of said unknown signals,
• a trigger pulse source for providing trigger pulses to said source of unknown signals and to said source of sampling pulses to initiate the application of said unknown signal to said monitor gate and the application of said sampling pulse to said monitor gate,
• means for recording the state of said monitor gate at the instance of each said sampling pulse application, said recording means including means relating the magnitude of said bias signal to the magnitude of said unknown signal at each sampling instant.