We use slow light and electromagnetically induced transparency to make and modulate single photons. Using spread spectrum technology we describe how a single photon may be hidden in an environment of noise photons. Article not available.
The slow light effects of an amplitude modulated Gaussian (AMG) pulse in a cesium atomic vapor are presented. In a single-Λ type electromagnetically induced transparency (EIT) medium, more severe distortion is observed for an AMG pulse than a Gaussian one. Using Fourier spectrum analysis, we find that the distortion, as well as the loss, is dominantly caused by linear absorption than dispersion. Accordingly, a compensation method is proposed to reshape the slow light pulse based on the transmission spectrum. In addition, we find a novel way to obtain simultaneous slow and fast light.
We propose a scheme to generate triple electromagnetically induced transparency (TEIT) where EIT is induced simultaneously for three weak slow light pulses.We calculate the complex polarizibilities and group velocities of the three slow light pulses in the weak field limit by means of the full Hamiltonian approach.It is shown that strong cross-phase modulation can be realized and large cross-phase shifts on the order of π radians can be generated for three slow weak pulses even if light pulses of ultrasmall energies, i.e. single photons, are involved.It is indicated that under certain conditions the three slow weak pulses can reach matching of group velocities in a single species of 87 Rb atoms.
Tunable on-chip optical delay has long been a key target for the research community, as it is the enabling technology behind delay lines, signal retiming and other applications vital to optical signal processing. To date, the field has been limited by high optical losses associated with slow light or delay structures. Here, we present a novel tunable delay line, based on a coupled cavity system exhibiting an electromagnetically induced transparency-like transmission spectrum, with record low loss, around 15 dB/ns. By tuning a single cavity, the delay of the complete structure can be tuned over 120 ps, with the maximum delay approaching 300 ps.