Phase shaping of single-photon wave packets

Although the phase of a coherent light field can be precisely known, this is not true for the phase of the individual photons that create the field, considered individually 1 . Phase changes within single-photon wave packets, however, have observable effects. In fact, actively controlling the phase of individual photons has been identified as a powerful resource for quantum communication protocols 2 , 3 . Here we demonstrate arbitrary phase control of a single photon. The phase modulation is applied without affecting the photon's amplitude profile and is verified by means of a two-photon quantum interference measurement 4 , 5 , demonstrating fermionic spatial behaviour of photon pairs. Combined with previously demonstrated control of a single photon's amplitude 6 , 7 , 8 , 9 , 10 , frequency 11 , and polarization 12 , the fully deterministic phase shaping presented here allows for the complete control of single-photon wave packets. Arbitrary phase control within a single photon wave packet is demonstrated and verified by two-photon quantum interference measurements. Combined with the previously demonstrated ability to control a single photon's amplitude, frequency and polarization, the phase shaping presented here allows for the complete control of single-photon wave packets.