def bits(self):
        """list of `Bits` for this `StateVector`

        :type: `Bits`
        """
        try:
            return self._bits
        except AttributeError:
            if self.dtype.name.startswith(('uint', 'int')):
                nbits = self.itemsize * 8
                self.bits = Bits(['Bit %d' % b for b in range(nbits)],
                                 channel=self.channel, epoch=self.epoch)
                return self.bits
            elif hasattr(self.channel, 'bits'):
                self.bits = self.channel.bits
                return self.bits
            return None
list of `Bits` for this `StateVector`

        :type: `Bits`