Balanced light detector

A random number generator (RNG) operable to generate one or more random bits of data, said RNG comprising:

• a first light detector having a first output, the first light detector configured to provide a first electrical signal from the first output, the first electrical signal representing light intensity of light received by the first light detector;
• a first amplifier coupled to the first output of the first light detector, the first amplifier operable to amplify the first electrical signal to yield a first amplified electrical signal;
• a second light detector having a second output, the second light detector configured to generate a second electrical signal from the second output, the second electrical signal representing light intensity of light received by the second light detector;
• a second amplifier coupled to the second output of the second light detector, the second amplifier operable to amplify the second electrical signal to yield a second amplified electrical signal;
• a common offset circuit operably coupled to the first and second outputs of the first and second light detectors, the common offset circuit configured to apply a common offset to the first and second outputs, whereby noise introduced to the first and second outputs by the common offset is common to the first and second outputs;
• and
• processing circuitry configured to generate a difference signal based on the first and second amplified electrical signals, the difference signal being indicative of quantum noise, the processing circuitry configured to output the one or more random bits of data based on the difference signal.

A method of detecting light, said method comprising:

• generating a first output from a first light detector based on light detected by the first light detector;
• amplifying the first output to yield a first amplified electrical signal;
• generating a second output from a second light detector based on light detected by the second light detector;
• amplifying the second output to yield a second amplified electrical signal;
• applying a common offset to the first and second outputs, wherein noise introduced by the common offset is common to both the first and second outputs;
• and
• generating a difference signal that is based on the first and second amplified electrical signals, wherein the noise introduced to the first and second outputs by the common offset is substantially absent from the difference signal.