  Quantum random number generators (QRNGs) output genuine random numbers based
upon the uncertainty principle. A QRNG contains two parts in general --- a
randomness source and a readout detector. How to remove detector imperfections
has been one of the most important questions in practical randomness
generation. We propose a simple solution, measurement-device-independent QRNG,
which not only removes all detector side channels but is robust against losses.
In contrast to previous fully device-independent QRNGs, our scheme does not
require high detector efficiency or nonlocality tests. Simulations show that
our protocol can be implemented efficiently with a practical coherent state
laser and other standard optical components. The security analysis of our QRNG
consists mainly of two parts: measurement tomography and randomness
quantification, where several new techniques are developed to characterize the
randomness associated with a positive-operator valued measure.
