  The ability to measure and control the carrier envelope phase (CEP) of
few-cycle laser pulses is of paramount importance for both frequency metrology
and attosecond science. Here, we present a phase meter relying on the
CEP-dependent photocurrents induced by circularly polarized few-cycle pulses
focused between electrodes in ambient air. The new device facilitates compact
single-shot, CEP measurements under ambient conditions and promises CEP tagging
at repetition rates orders of magnitude higher than most conventional CEP
detection schemes as well as straightforward implementation at longer
wavelengths.
